Small grain production guide |
Previous | 1 of 3 | Next |
|
small (250x250 max)
medium (500x500 max)
Large
Extra Large
large ( > 500x500)
Full Resolution
|
This page
All
|
-
152594.pdf
[72.84 MB]
Link will provide options to open or save document.
File Format:
Adobe Reader
Small Grain Production Guide Revised March 2013 Small Grain Production Guide Revised March 2013 Prepared by Randy Weisz, Crop Science Extension Specialist, NC State University With additional contributions from Gaylon Ambrose, County Extension Agent, Beaufort County Cooperative Extension Steve Bambara, Retired Entomology Extension Specialist, NC State University Christina Cowger, USDA–ARS, Plant Pathologist, NC State University Carl Crozier, Soil Science Extension Specialist, NC State University Wesley Everman, Weed Science Extension Specialist, NC State University Ron Heiniger, Crop Science Extension Specialist, NC State University D. Ames Herbert, Jr., Professor, Entomology, Virginia Polytechnic Institute David Jordan, Crop Science Extension Specialist, NC State University Paul Murphy, Small Grains Breeder, NC State University Dominic Reisig, Entomology Extension Specialist, NC State University Published by North Carolina Cooperative Extension Service College of Agriculture & Life Sciences North Carolina State University Acknowledgments This publication is supported in part by a grant from the NC Small Grain Growers Association, Inc. The association provides funds to supplement public appropriations and research programs at NC State University for the benefit of the small grain industry, general consumers, and the public at large. Contents 1. Small Grain Growth and Development . . . . . . 1 2. Wheat Enterprise Budgets . . . . . . . . 5 3. Small Grain Variety Selection . . . . . . . 9 4. To Plant or Drill: Does Row Spacing Matter? . . . . . 13 5. Small Grain Planting Dates . . . . . . . . 14 6. Beating Soybean Harvest: A Very Early Wheat-Planting System . . . 16 7. Small Grain Seeding Rates for North Carolina . . . . . 19 8. Nitrogen Management for Small Grains . . . . . . 25 9. Nutrient Management for Small Grains . . . . . . 32 10. Insect Pest Management for Small Grains . . . . . . 39 11. Insect Pests of Stored Small Grains . . . . . . 51 12. Small Grain Disease Management . . . . . . . 56 13. Small Grain Weed Control . . . . . . . . 70 1. Small Grain Growth And Development By Randy Weisz Small grains respond best to inputs when they are applied at specific growth stages. Therefore, it is important to understand how small grains develop so you can identify the different growth stages and properly time applications of pesticides, nitrogen, and other inputs. Small grain development can be divided into four phases: vegetative growth or tillering, stem extension, heading and flowering, and kernel formation and ripening. The specific growth stages associated with these phases have been described in several scales. The most popular scales are the Feekes and Zadoks stages of development (Table 1-1). Both scales will be described in this chapter, but we will use the Zadoks system in the rest of this production guide. Vegetative Growth And Tillering In NC, wheat is typically planted from mid-October through late November. Plants emerge about one week after planting (Feekes 1 or Zadoks 11, see Figure 1-1), and leaves begin to develop on the mainstem or shoot. When the fourth leaf unfolds, the first tiller starts to grow (Feekes 2 or Zadoks 21), and a new tiller is produced with every subsequent unfolding of a leaf on the mainstem. Tillering continues as long as the plants are healthy, unstressed, and the temperature is warm. Tillers are important because each tiller can only produce one grain head, and tillers that develop in the fall often produce the largest heads and contribute the most to crop yield. Tillering slows down or stops when winter weather turns cold. When the weather warms up again in late January or February, another brief period of further vegetative growth occurs when spring tillers can grow if nitrogen is available. In NC, tillering and vegetative growth usually end between late Febuary and mid-March (Feekes 4-5 or Zadoks 30). Growth And Development 1 Stem Extension During Feekes growth stage 4-5 or Zadoks 30, small grains switch from producing tillers to starting reproductive growth. In the first phase of reproductive growth, the stems extend and the plant grows taller. The growing point, which was below ground during tillering, moves upward through the elongating stem and begins the transition into what will become a head of grain. The first easily 2 Growth And Development Emergence Feekes 1 Zadoks 11 Three leaves Feekes 1 Zadoks 13 First Tiller Feekes 2 Zadoks 21 Three Tillers Feekes 2 Zadoks 23 Tillering Ends Feekes 4-5 Zadoks 30 Figure 1-1. Vegetative growth and tillering phase of wheat development. More details and pictures of these growth stages can be found online. First Joint Feekes 6 Zadoks 31 Flag Leaf Visible Feekes 8 Zadoks 37 Flag Leaf Ligule Visible & Boot Swollen Feekes 9 to 10 Zadoks 39 to 45 Boot Splitting Feekes 10 Zadoks 47 Figure 1-2. Stem extension. More details and pictures of these growth stages can be found online. detected sign that this has started is the appearance of the first node or joint at Feekes growth stage 6 or Zadoks 31 (see Figure 1-2). The joint is a small swelling of the stem that somewhat resembles a joint on a human finger. As the stem continues to develop, several joints may appear. Knowing this is important for the small grain producer: the developing grain head is always inside the stem just above the highest joint. That means that if the stem is damaged by being driven over, a freeze, or lodging, the developing head is also likely to be damaged. Additionally if liquid nitrogen fertilizer is applied after jointing, the developing grain head is almost always burned, resulting in potential yield reductions. The flag leaf is the last leaf to develop on the small grain plant. The growth stage when it first appears at the top of the stem is defined as Feekes 8 or Zadoks 37. As the flag leaf unfolds, the ligule or collar at the base of the leaf become visible at Feekes 9 or Zadoks 39. At this time the developing grain head is getting large enough that the stem containing it swells. This swelling is called the boot. As the grain head continues to grow it eventually causes the boot to split open at Zadoks 47. Heading and Flowering The plant starts the heading phase of development when the first spikelet has emerged from the boot at Feekes 10.1 or Zadoks 50. Over the next few days the grain head will fully emerge from the boot at Feekes 10.5 or Zadoks 58 (see Figure 1-3). About one week later, the head will begin to shed pollen as flowering begins. Kernel Formation A few hours after pollination, grain kernels begin to form. Dry matter starts accumulating in the kernels, and a clear to milky fluid can be squeezed from them. This is known as the milk stage of kernel formation. Forage harvest during the milk stage results in the best combination of nutrient quality and yield. With continued growth and water loss, the kernel content changes from a milky fluid to a doughy or mealy consistency. This is called the soft dough stage. At soft dough, the green color of the head begins to fade (Photo 1-1) and harvesting forage at this time results in maximum dry matter Growth And Development 3 ¾ Of Head Visible Feekes 10.4 Zadoks 56 Fully Headed Feekes 10.5 Zadoks 58 Flowering Feekes 10.51 to 10.53 Zadoks 60 to 68 Figure 1-3. Heading and flowering. More details and pictures of these growth stages can be found online. Photo 1-1. Soft dough. Feekes growth stage 11.2 or Zadoks 85. yield. When the water content of the kernels drops to about 30 percent, the plant loses most of the green color but the kernels can still be cut by pressing with a thumbnail. This is called the hard dough stage. This marks the end of all insect and disease pest management. When the kernels reach 13 to 14 percent moisture, the grain is harvest ripe (Photo 1-2). References Some materials in this chapter were adapted from these references: Alley, M. M., D. E. Brann, E. L. Stromberg, E. S. Hagood, A. Herbert, and E.C. Jones. 1993. Intensive Soft Red Winter Wheat: A Management Guide (Publication 424-803). Blacksburg: Virginia Polytechnic Institute, Cooperative Extension Service. Hilfliger, E. (Ed.). 1980. Wheat-documenta. CIBA-GEIGY, Technical Monograph. Basle, Switzerland: CIBA GEIGY Ltd Strand, L. 1990. Integrated Pest Management for Small Grains (Agricultural and Natural Resources Publication 3333). Oakland, CA: University of California Statewide IPM Project. 4 Growth And Development Table 1-1. Feekes and Zadoks scales of small grain development. Feekes Zadoks General Description Vegetative Growth & Tillering 1 10 1st leaf through coleoptile 12 2nd leaf unfolded 13 3rd leaf unfolded 2 21 Main shoot and 1 tiller 22 Main shoot and 2 tillers 23 Main shoot and 3 tillers 3 26 Main shoot and 6 tillers 4-5 30 Tillering ended, leaf sheaths strongly erected Stem Extension 6 31 1st node detectable 7 32 2nd node detectable 8 37 Flag leaf just visible 9 39 Flag leaf ligule visible 10 45 Boots swollen Heading and Flowering 10.1 50 1st spikelet visible through split boot 10.2 52 ¼ head emerged 10.3 54 ½ head emerged 10.4 56 ¾ head emerged 10.5 58 Head fully emerged 10.51 60 Start of flowering Kernel Formation 10.54 71 Milk stage - watery ripe 11.1 75 Milk stage - medium milk 11.2 85 Soft dough 87 Hard dough 11.3 91 Dry matter accumulation ends 11.4 92 Harvest ripe Photo 1-2. Harvest ripe. Feekes growth stage 11.4 or Zadoks 92. 2. Wheat Enterprise Budgets By Randy Weisz and Ron Heiniger In NC, wheat is grown in a double-cropped soybean production system. This allows the risk of crop failure to be spread across two harvests and increases income potential. A full-season soybean budget is included for comparison with wheat double-cropped bean production. At the wheat and soybean prices that the market has been offering in 2012 and 2013 this double-cropped system is highly profitable. The wheat budgets presented here are based on practices outlined throughout this production guide. If you have a smaller farm, smaller equipment, or use more inputs than assumed in these budgets, costs will be higher than those shown in the following tables. Please note that these budgets are for planning purposes only. Items for All Wheat Bean Budgets • Wheat and soybeans are planted with a Great Plains 22-foot wide no-till drill. • Pre-plant fertilizer to provide 27 pounds N, 70 pounds P2O5, and 100 pounds K2O per acre is applied by a commercial applicator as 152 pounds of diammonium phosphate (18-46-0) and 167 pounds of potassium chloride (0-0-60). • Lime is applied once every three years and is prorated across each season. • All herbicides, fungicides, insecticides, and top-dress N-fertilizer are applied using a HiBoy with a 90-foot boom. • A broadleaf herbicide is applied in February. • Top-dress N (100 pounds per acre) is applied in March as 30% N solution. • A fungicide is applied to the wheat between flag leaf and heading. • An insecticide is applied to the wheat either in March tank-mixed with top-dress N, or in April tank-mixed with the fungicide. • Wheat and beans are harvested by combine with a 30-foot wide header. • All soybeans are Roundup Ready planted no-till. • A herbicide application is made to the soybeans pre-plant to help prevent development of glyphosate resistance. • Glyphosate is applied post-emergence. • An insecticide is applied to all soybean acreage in August. • One-fourth of the land in production is rented at $100 per acre. Conventional-Till Wheat No-Till Beans Budget • In the fall, field preparation is made with two passes of a 30-foot-wide disk harrow, and one pass with a 29-foot-wide field cultivator. • Wheat is planted at 1.5 million seeds per acre (35 seeds per square foot) or about 2.4 bags of seed per acre. • Soybeans are planted at 160,000 seed per acre. No-Till Wheat No-Till Soybeans Budget • In the fall, field preparation is limited to one application of glyphosate applied pre-plant. • Wheat is planted at about 2.7 bags of seed per acre. • Soybeans are planted at 160,000 seed per acre. Full-Season No-Till Soybean Budget • This budget is identical to the double-cropped soybean budgets except that soybeans are planted in May and expected to yield more, no pre-plant N is applied, and the rates of P2O5, and K2O are reduced. Wheat Enterprise budgets 5 6 Wheat Enterprise budgets Table 2-1. No-till wheat and double-cropped no-till Roundup Ready soybean budget. Unit Quantity Price or Cost/Unit Total per Acre Your Farm 1. GROSS RECEIPTS Wheat BU 55 $8.00 $440.00 ___________ Soybeans BU 30 $14.00 $420.00 ___________ TOTAL RECEIPTS: $860.00 ___________ 2. VARIABLE COSTS Wheat seed BU 2.7 $15.00 $40.50 ___________ Soybean RR seed THOU. 160 $0.36 $57.60 ___________ Pre-plant fertilizer DAP LBS 152 $0.36 $54.72 ___________ Potassium chloride LBS 167 $0.32 $53.44 ___________ Commercial spreading ACRE 1 $6.00 $6.00 ___________ Top-dress N (30% solution) LBS 90 $0.62 $55.80 ___________ Lime (Prorated) TON 0.33 $48.50 $16.01 ___________ Herbicides for wheat ACRE 1 $21.54 $21.54 ___________ Herbicides for soybeans ACRE 1 $33.65 $33.65 ___________ Fungicides for wheat ACRE 1 $10.80 $10.80 ___________ Insecticides for wheat ACRE 1 $4.63 $4.63 ___________ Insecticides for soybeans ACRE 1 $11.85 $11.85 Crop insurance for wheat ACRE 1 $6.00 $6.00 ___________ Crop insurance for beans ACRE 1 $10.00 $10.00 ___________ Hauling wheat BU 55 $0.15 $8.25 ___________ Hauling soybeans BU 30 $0.15 $4.50 ___________ Tractor/Machinery ACRE 1 $25.48 $25.48 ___________ Labor HRS 1.35 $7.25 $9.79 ___________ Interest on Op. Cap. DOL $190.09 6.50% $12.36 ___________ TOTAL VARIABLE COSTS: $442.91 ___________ 3. INCOME ABOVE VARIABLE COSTS: $417.09 ___________ 4. FIXED COSTS Tractor/Machinery ACRE 1 $39.06 $39.06 ___________ TOTAL FIXED COSTS: $39.06 ___________ 5. OTHER COSTS Land rent ACRE 0.25 $100.00 $25.00 ___________ General overhead DOL $442.92 4.5% $19.93 ___________ TOTAL OTHER COSTS: $44.93 ___________ 6. TOTAL COSTS: $526.90 ___________ 7. NET RETURNS TO RISK AND MANAGEMENT: $333.10 ___________ Wheat Enterprise budgets 7 Table 2-2. Full-till wheat and double-cropped no-till Roundup Ready soybean budget. Unit Quantity Price or Cost/Unit Total per Acre Your Farm 1. GROSS RECEIPTS Wheat BU 55 $8.00 $440.00 ___________ Soybeans BU 30 $14.00 $420.00 ___________ TOTAL RECEIPTS: $860.00 ___________ 2. VARIABLE COSTS Wheat seed BU 2.4 $15.00 $36.00 ___________ Soybean RR seed THOU. 160 $0.36 $57.60 ___________ Pre-plant fertilizer DAP LBS 152 $0.36 $54.72 ___________ Potassium chloride LBS 167 $0.32 $53.44 ___________ Commercial spreading ACRE 1 $6.00 $6.00 ___________ Top-dress N (30% solution) LBS 90 $0.62 $55.80 ___________ Lime (Prorated) TON 0.33 $48.50 $16.01 ___________ Herbicides for wheat ACRE 1 $10.57 $10.57 ___________ Herbicides for soybeans ACRE 1 $33.65 $33.65 ___________ Fungicides for wheat ACRE 1 $10.80 $10.80 ___________ Insecticides for wheat ACRE 1 $4.63 $4.63 ___________ Insecticides for soybeans ACRE 1 $11.85 $11.85 Crop insurance for wheat ACRE 1 $6.00 $6.00 ___________ Crop insurance for beans ACRE 1 $10.00 $10.00 ___________ Hauling wheat BU 55 $0.15 $8.25 ___________ Hauling soybeans BU 30 $0.15 $4.50 ___________ Tractor/Machinery ACRE 1 $27.96 $27.96 ___________ Labor HRS 1.76 $7.25 $12.76 ___________ Interest on Op. Cap. DOL $183.59 6.50% $11.93 ___________ TOTAL VARIABLE COSTS: $432.47 ___________ 3. INCOME ABOVE VARIABLE COSTS: $427.53 ___________ 4. FIXED COSTS Tractor/Machinery ACRE 1 $43.93 $43.93 ___________ TOTAL FIXED COSTS: $43.93 ___________ 5. OTHER COSTS Land rent ACRE 0.25 $100.00 $25.00 ___________ General overhead DOL $432.47 4.5% $19.46 ___________ TOTAL OTHER COSTS: $44.46 ___________ 6. TOTAL COSTS: $520.86 ___________ 7. NET RETURNS TO RISK AND MANAGEMENT: $339.14 ___________ 8 Wheat Enterprise budgets Table 2-3. Full-season no-till Roundup Ready soybean budget. Unit Quantity Price or Cost/Unit Total per Acre Your Farm 1. GROSS RECEIPTS Soybeans BU 37 $14.00 $518.00 ___________ TOTAL RECEIPTS: $518.00 ___________ 2. VARIABLE COSTS Soybean RR seed THOU. 160 $0.36 $57.60 Fertilizer ___________ Pre-plant P2O5 LBS 65 $0.41 $26.65 ___________ Pre-plant K2O LBS 83 $0.55 $45.65 Commercial spreading ACRE 1 $6.00 $6.00 ___________ Lime (Prorated) TON 0.33 $48.50 $16.01 ___________ Herbicides for soybeans ACRE 1 $33.65 $33.65 ___________ Insecticides for soybeans ACRE 1 $11.85 $11.85 Crop insurance for beans ACRE 1 $10.00 $10.00 ___________ Hauling soybeans BU 37 $0.15 $5.55 ___________ Tractor/Machinery ACRE 1 $10.72 $10.72 ___________ Labor HRS 0.61 $7.25 $4.42 ___________ Interest on Op. Cap. DOL $98.14 6.50% $6.38 ___________ TOTAL VARIABLE COSTS: $234.48 ___________ 3. INCOME ABOVE VARIABLE COSTS: $283.52 ___________ 4. FIXED COSTS Tractor/Machinery ACRE 1 $17.69 $17.69 ___________ TOTAL FIXED COSTS: $17.69 ___________ 5. OTHER COSTS Land rent ACRE 0.25 $100.00 $25.00 ___________ General overhead DOL $234.48 4.5% $10.55 ___________ TOTAL OTHER COSTS: $35.55 ___________ 6. TOTAL COSTS: $287.72 ___________ 7. NET RETURNS TO RISK AND MANAGEMENT: $230.28 ___________ 3. Small Grain Variety Selection Randy Weisz, Paul Murphy, and Christina Cowger Keep Up to Date! Small grain varieties generally have the highest yields and milling quality during the first couple of years after their release. Consequently, the varieties grown on a farm should change over time. This makes it important to keep up to date on newly released varieties and how they are doing in NC. Plant newer varieties on small acreage to assess performance. Plant the most consistent performers on most of the available cropland, and phase out the older varieties showing signs of succumbing to disease and insect pressures. Getting Unbiased Information The best source of unbiased public and private wheat variety performance information for NC is the Wheat Variety Performance and Recommendations SmartGrains Newsletter (www.smallgrains.ncsu.edu/ _Misc/_VarietySelection.pdf), which is released every July at NC State University and prepared by Randy Weisz (in the Crop Science Department at NC State) and Christina Cowger (USDA– Agricultural Research Service, Plant Pathology Department). This newsletter is based on the Official Variety Test Report or OVT (www.ncovt.com), and additional Cooperative Extension variety testing projects around NC. This newsletter groups wheat varieties into four categories: above average yielding, above average but less consistently yielding, average yielding, and below average yielding. It also gives heading date and pest resistance information about each wheat variety. The best source of unbiased variety performance information for other small grains is the OVT (www.ncovt.com) produced annually by the Crop Science Department at NC State University. It is also updated every July. Additionally, producers in counties adjacent to VA may find the Virginia Official Variety Test Report to be valuable (http://pubs.ext.vt.edu/category/ grains.html). Guidelines for Specific Variety Selection Avoid Varieties Not Adapted to North Carolina All small grain varieties that have been in the OVT for more than one year are usually good candidates for production. Avoid investing in varieties that have not been entered into these tests because they usually are not adapted to NC’s growing conditions and may be highly susceptible to local diseases or mature too late to follow with double-cropped soybeans. Only varieties that have been in the OVT for at least two years are included in the Wheat Variety Performance and Recommendations SmartGrains Newsletter. Plant at Least Three Varieties Small grain variety performance can vary greatly from one year to the next. This makes it nearly impossible to pick a single best variety. Consequently, producers should plant three or more varieties every season. Growing at least three varieties will reduce the risk of freeze injury, pest damage, and other forms of crop failure and maximize the potential for a high-yielding crop. Pick High Yielding Varieties Using the Wheat Variety Performance and Recommendations SmartGrains Newsletter, the “Above Average Yielding” varieties are good first choices. The next to consider are the “Above Average but Less Consistent Yielders.” These are varieties that on average had high yield but are more risky. Finally, the “Average Yielding Varieties” are likely to Variety Selection 9 produce acceptable yields but may not win a yield contest. Avoid Spring Freeze Damage Heading date is an important indication of how susceptible a variety will be to late-spring freeze damage. Early heading varieties are the most susceptible to freeze damage, while late heading varieties are the most likely to avoid yield loss due to spring freezes. Figure 3-1 shows how different varieties were damaged by the April 2007 freeze. Early heading varieties (shown in solid red) were severely damaged. Medium-early heading varieties (striped red) also tended to be more severely damaged. But late heading varieties (in black) were barely damaged at all. In 2008, spring freeze damage was observed at some locations and early and medium-early varieties were again the most damaged. Heading date also indicates when a wheat variety should ideally be planted. Medium and late heading wheat varieties tend to do best when planted at the start of the planting season, and consequently should be the first varieties a producer plants. Early and medium-early varieties tend to produce the highest yields when planted later in the fall. Barley is the earliest of the small grain species to head, so it is at greatest risk of suffering spring freeze damage and yield loss. In NC, the variety Boone had been a long-time standard for barley producers and rarely suffered late-spring freeze damage. Current varieties such as Thoroughbred and Dan have similar heading dates as compared to 10 Variety Selection AGS 2000 SS 520 Pioneer 26R31 AGS 2000/USG 3209 Featherstone 176 SS 8404 Renwood 3260 USG 3209 AGS 2060 Coker 9511 USG 3342 Coker 9553 SS 560 Chesapeake SS 8461 USG 3592 Coker 9312 Panola NC Neuse/USG 3592 Tribute/Roane SS 8308 USG 3910 SS MPV 57 Pioneer 26R12 Pioneer 26R24 Terral TV8558 USG 3665 Pioneer 26R15 SS 8302 SS 8309 NC Neuse Coker 9436 Coker 9184 Roane NC Neuse/Roane 0 10 20 30 40 50 60 70 Freeze Damage (%) 2007 Freeze Damage Early Heading Medium-Early Heading Medium Heading Late Heading Figure 3-1. Damage caused by the April 2007 freeze for different wheat varieties. Early heading varieties (shown in solid red) were severely damaged. Medium-early heading varieties (striped red) also tended to be more severely damaged. But, late heading varieties (shown in black) were barely damaged at all. Boone. So barley varieties that head earlier than Thoroughbred or Dan should be viewed as having a greater risk of yield reduction from freeze damage. Tailor Variety Selection to Match the Most Frequent Local Yield Robbing Factors Variety selection is the best defense against most pest problems encountered in NC. The three most common foliar fungal small grain diseases are powdery mildew, leaf rust, and Stagonosprora nodorum blotch (Photo 3-1). Wheat varieties that are resistant (or moderately resistant) to these diseases rarely require a fungicide application. Two soilborne viral diseases (soilborne wheat mosaic virus and wheat spindle streak virus) are common in some areas, and variety resistance is the only control method for these diseases (Photo 3-2). Fusarium sp. head blight or scab (Photo 3-2) can be problematic primarily in years with warm, moist weather at heading, and variety resistance is the best control method producers have. In recent years, numerous wheat fields have suffered losses due to Hessian fly (Photo 3-2). Wheat growers with a history of Hessian fly problems should select Hessian fly-resistant varieties. Here are some fine-tuning guidelines: • Central piedmont. The most common yield robbers in this area include spring freeze damage, barley yellow dwarf virus, and scab. Varieties that are high yielding, late heading (to avoid freeze damage), and resistant to these two diseases would be ideal for the NC piedmont. • Coastal plain. Powdery mildew, leaf rust, and soilborne mosaic virus are common wheat pests in the NC coastal plain. Ideal wheat varieties for this region should be high yielding and have resistance to all three of these diseases. • Tidewater. Hessian fly and soilborne mosaic virus have been frequent yield robbers in the NC tidewater. Ideal wheat varieties are high yielding and have resistance to soilborne diseases. Where Hessian fly has been a problem, varieties with resistance to it should also be selected. High Test Weight Varieties High test weight is usually associated with good quality. A low test weight will result in dockage at the elevator. Some varieties consistently have superior test weight. Even a high test weight variety, however, will produce a low test weight grain if drought, potassium or sulfur deficiencies, fungal diseases, lodging, or wet weather at harvest occur. Coastal plain producers with deep sandy soils who need high test weight grain should watch for potassium and sulfur deficiencies. Variety Selection 11 Photo 3-1. The three most common foliar fungal small grain diseases are powdery mildew (left), Stagonosprora nodorum blotch (center), and leaf rust (right). Wheat varieties that are resistant (or moderately resistant) to these diseases rarely require a fungicide application. Lodging Lodging is generally a greater problem in barley and oats than in wheat. Under intensive management practices, however, lodging will occur at a greater frequency in all small grains. A lodged crop can reduce test weight and slow combine operation. Milling and Baking Quality of Wheat Millers and bakers in NC use wheat for many diverse products, and certain varieties are superior to others for production of specific products. Therefore, if you plan to grow wheat for sale directly to a mill, discuss variety choice with the mill quality-control staff. Just like test weight, even a high-baking-quality variety can produce a low-quality grain if nitrogen, potassium or sulfur deficiencies, fungal diseases, lodging, or wet weather at harvest occur. Special Consideration for No-Till Variety Selection No-till producers should keep several additional facts in mind when choosing varieties. Tillering and fall growth are often slower in no-till small grains. Consequently, no-till producers often achieve higher yields if they plant during, or slightly ahead, of the opening planting dates (see chapter 5, “Small Grain Planting Dates” in this production guide: www.smallgrains.ncsu.edu/_Pubs/PG/Pdates.pdf). Planting early requires special care to select varieties that (1) are “late” heading to avoid freeze damage, (2) have “good” Hessian fly resistance to prevent fall infestations (especially important in the NC coastal plain and tidewater), (3) have at least moderate resistance to barley yellow dwarf virus (especially important in the NC piedmont), and (4) have at least moderate resistance to powdery mildew if planting in areas where powdery mildew is common. 12 Variety Selection Photo 3-2. Variety resistance is the best protection against Fusarium head scab (left). The only control method for soilborne mosaic virus (center) is variety resistance. Producers with a history of Hessian fly (right) should grow resistant varieties. 4. To Plant or Drill: Does Row Spacing Matter? Randy Weisz Many growers have wondered if they could plant wheat with the same implement they use to plant narrow-row corn or soybeans. Does it make a difference if wheat is drilled in 6- or 7.5-inch rows compared to being planted in 15-inch rows? If it does not make a difference, then the cost of replacing a drill could be avoided. We tested this idea in Salisbury in 2012, and Andrew Gardner tested it in Union Couny in 2010 and 2011. Our results were similar to those previously reported from other states. Figure 4-1 shows the results from winter wheat row-spacing tests conducted at 35 locations across six states (NC, VA, GA, PA, OH, and IN). As row spacing increases, wheat yield declines. The lowest yields were with 20-inch rows. Fifteen-inch rows had an average yield (BLUE line, Figure 4-1) of 60.8 bushels per acre, 7.5-inch rows averaged 68.7 bushels per acre, and 4-inch rows averaged 76.1 bushels per acre. The difference between 7.5-inch and 15-inch rows was 7.9 bushels per acre. If the price of wheat is $7.50 per bushel, that comes to $59.25 lost per acre by planting instead of drilling wheat. Does Row Spacing Matter? 13 50 60 70 80 90 2 4 6 8 10 12 14 16 18 20 Yield (bu/acre) Row Spacing (inches) All VA - 3 GA - 2 IN - 4 OH - 8 NC - 3 PA - 15 Winter Wheat Row Spacing Studies Test Locations Figure 4-1. Wheat yields at different row-spacings from studies conducted in NC, VA, GA, PA, OH, and IN. Some data from: Beuerlein, LaFever. Applied Agric. Res. 4:47-50, and 4:106-110; Gardner. www.smallgrains.ncsu.edu/_Pubs/OnFarm/ Union2010.pdf, and www.smallgrains.ncsu.edu/_Pubs/OnFarm/Union2011.pdf; Joseph, Alley, Brann, Gravelle. Agron. J. 77:211-214; Johnson, Hargrove, Moss. Agron. J. 80:164-166; Marshall, Ohm. Agron. J. 79:1027-1030, and Roth, Marshall, Hatley, Hill. Agron. J. 76:379-383. 5. Small Grain Planting Dates Randy Weisz and Ron Heiniger For producers of small grains, the goal is to select a planting date that gives an opportunity to develop as many fall tillers as possible while avoiding potentially severe damage associated with fall insect and disease infestations or an early spring freeze. Small grain tillers produced in the fall are most likely to have large heads with kernels of high-test weight: the two components of a high-yielding crop. Fall tillers also tend to have stronger root systems and consequently may be more stress resistant. The key advantage to planting early in the fall is the opportunity to make the most of warmer temperatures. The warmer the weather, the more tillers are likely to be produced. Cold temperatures impede growth, so it is important to plant small grains while there is still enough time and mild weather for tillers to form before winter sets in. On the other hand, planting too early can result in increased risk of diseases such as barley yellow dwarf virus and powdery mildew, increased risk of Hessian fly infestations, and increased risk of spring freeze damage. The same warm temperatures that enhance wheat growth also promote the development of insects and diseases and shorten the period from emergence to flowering. At least one night below 32oF is required to reduce Hessian fly or aphid populations and to slow disease development. Therefore, the selection of a planting date for small grains is a balance between achieving good fall growth and avoiding severe damage. Wheat The traditional guideline for finding the right compromise between planting early enough to encourage tillering, but late enough to avoid insect and disease problems, has been to plant wheat within one week of the first frost. Figure 5-1 shows starting dates for wheat planting in NC. The dates shown in this map are one week earlier than the 30- year average local freeze dates for weather stations throughout NC. These dates mark the start of the wheat planting season. In most parts of the NC tidewater, coastal plain, and southern piedmont, planting on these dates will allow wheat plants to develop two to three additional large tillers by February 1. That puts the crop in an excellent position for high yield potential and reduces the likelihood of needing to apply two applications of N fertilizer in the spring. It also assures that some cold weather will occur shortly after the seedlings emerge to reduce disease and insect pest activity. The dates shown in Figure 5-1, however, are often when soybean, cotton, and (in some parts of NC) peanut harvest is underway. This may force producers to plant later. Planting wheat later than the dates shown in Figure 5-1 can have a significant impact on a crop’s yield potential. For example, based on average NC weather records, planting 14 days later than the dates shown in Figure 5-1 usually results in enough warm weather to produce only one additional large tiller per plant by February 1 in the NC tidewater and central to southern coastal plain. In the rest of the state, not enough warm weather may occur to get even a single additional large tiller to develop by February 1. This makes it very important to ensure that a late planted crop was drilled in at higher seeding rates (see chapter 7, “Small Grain Seeding Rates” in this production guide: www.smallgrains.ncsu.edu/_Pubs/PG/Srates.pdf) and to scout the wheat in late January to determine if an early N fertilizer application will be required in February to stimulate further tiller development in the spring (see chapter 8, “Nitrogen Management for Small Grains” in this production guide: www.sm a l l g r a ins. n c s u . e du/_Pubs /PG/ Nitrogen.pdf). Barley, Oats, Rye, and Triticale Barley and oats should be planted about 5 to 10 days earlier than the dates shown for wheat in 14 Planting Dates Figure 5-1. Rye planting dates are similar to those for wheat. Triticale varieties that have been developed for NC, like Arcia, can be planted on the same dates as wheat. Trical triticale varieties that have been tested in NC and shown to head at the same time as wheat can also be planted on the same dates shown in Figure 5-1. However, some triticale varieties (such as Trical 498) are early heading, and need to be planted late to avoid spring freeze damage. It is important to know the maturity rating for the triticale variety before selecting a planting date. Special Considerations for No-Till Heavy residue left on the soil surface can reduce soil temperatures. This results in slower germination and tiller growth. Because fall growth can be reduced in no-till, planting small grains early becomes even more important. Establishing a healthy, uniform stand by planting close to the dates shown in Figure 5-1 may be a key to achieving high yields in no-till. Some successful no-till producers say they need to plant on or even a little earlier than these dates (see chapter 6 “Beating Soybean Harvest: A Very-Early-Wheat-Planting System” in this production guide: www.smallgrains.ncsu.edu/_Pubs/PG/ VeryEarly.pdf). Special Considerations for Hessian Fly Hessian fly has become a serious wheat pest in NC. Because Hessian fly adults are killed by freezing temperatures, a traditional method for preventing Hessian fly infestation is to delay planting until after the first freeze (often called the fly-free date). The fly-free date concept has not worked well in NC (see chapter 11, “Insect Pest Management,” in this guide: www.smallgrains.ncsu.edu/_Pubs/PG/Insects.pdf). Often a “killing freeze” does not occur until December in many areas of NC, after most growers need to have wheat planted if they want to have enough fall growth to produce high yields. Delayed planting will only prevent Hessian fly infestations if a freeze has occurred. Planting Dates 15 Murphy Asheville Jefferson Mt Airy Mocksville Salisbury N. Wilkesboro Hickory Forest City Gastonia Concord Albemarle Monroe Jackson Springs Reidsville Oxford Arcola Siler City Raleigh Sanford Smithfield Fayetteville Laurinburg Whiteville Willmington Longwood Warsaw GoldsboroKinston Rocky Mt Murfreesboro Elizabeth City Plymouth New Holland Bayboro Morehead City Hofmann Forest Lumberton Sept 25 - 30 Sept 30 - Oct 5 Oct 5 - 10 Oct 10 - 15 Oct 15 - 20 Oct 15 - 20 Oct 20 - 25 Oct 15 - 20 Oct 25 - 30 Oct 25 - 30 Oct 20 - 25 Oct 25 - 30 Oct 30 - Nov 4 Oct 30 - Nov 4 Oct 30 - Nov 4 Figure 5-1. The start of wheat planting dates. The dates shown on this map are 7 days earlier than the date when there is a 50% chance of having a freeze. 6. Beating Soybean Harvest: A Very Early Wheat-Planting System Randy Weisz Why Plant Before Soybean Harvest In NC, the ideal dates for planting wheat (see Figure 5-1: www.smallgrains.ncsu.edu/_Pubs/PG/ Pdates.pdf) herald the beginning of soybean and cotton harvest. Consequently, wheat planting is often delayed until cold wet weather has set in, and wheat development suffers. Research in Virginia and NC has shown that up to 85 percent of the yield in a any given wheat field is made up by grain heads formed on tillers that developed in the warm fall weather. When planting is delayed, there is less time for fall tillers to develop and this results in reduced yield potential. This is especially true for no-till. Wheat planted no-till (especially in NC coastal plain and tidewater soils) tends to grow and tiller more slowly than when planted in conventionally tilled seedbeds. Planting early is one way to help no-till seedlings make up for this slower growth and produce more fall tillers. It would be ideal if wheat could be planted before the start of soybean or cotton harvest to take full advantage of the warm tiller-inducing fall weather. Challenges and Solutions I n c h a p t e r 5 , “ S m a l l Gr a i n P l a n t i n g Dates” (www.smallgrains.ncsu.edu/_Pubs/PG/ Pdates.pdf), we stated that the ideal time to plant wheat was within 7 to 10 days of the first freeze. Planting earlier than that puts the crop at risk of early season insect damage, including wireworm (especially in no-till production in the NC coastal plain), Hessian fly, and aphid feeding that can spread barley yellow dwarf virus. One way to avoid these problems is to use an insecticidal seed treatment (such as GauchoXT or Cruiser/ Dividend). These seed treatments can give about 19 days of protection from these insects. A second potential problem is too much fall tiller production resulting in very thick stands that may lodge before the end of winter. A good way to avoid this is to reduce seeding rates. Finally, many growers will say that they cannot plant too early because of the risk of spring freeze damage. The earlier wheat is planted, the earlier it heads out in the spring. Once wheat has headed, it becomes freeze tender and can lose yield if a freeze occurs. In NC most “early-heading” wheat varieties head in the first week of April. “Late-heading” varieties may head out one to two weeks later. Consequently, if there is a freeze the end of the first week in April, early-heading varieties may be damaged while the late varieties may escape. Making It Work There are five essential parts to the very early wheat-planting system. Planting 10 Days to Two Weeks Early Plant 10 days to two weeks earlier than the dates shown in Figure 5-1: www.smallgrains.ncsu.edu/ _Pubs/PG/Pdates.pdf. Because the seed treatments used in this system only give limited protection, planting should not be more than about 14 days early. In the NC central piedmont (at Salisbury), we have been planting between September 29 and October 3. In the NC central coastal plain (at Kinston), we have been planting from October 6 through October 8. In the NC tidewater at Plymouth and Terra Ceia, we’ve planted between October 8 and 11. Plant Only Late-Heading Varieties Late-heading varieties have the lowest risk of damage from a spring freeze. These are the only 16 Very Early Planting varieties that should be used in the very early planting system. This system has been tested with NC-Neuse and Roane (two late-heading wheat varieties) for six years in Salisbury, and shown to work well. Always Use an Insecticidal Seed Treatment Treating all seed with an insecticidal seed treatment such as GauchoXT or Cruiser/Dividend is critically important. In our very early planting trials in the NC piedmont, using an insecticidal seed treatment usually resulted in a 10-bushel-per-acre yield advantage over untreated seed. In eastern NC, the seed treatment is critical to prevent Hessian fly, wireworm, and aphid infestations. Plant at Reduced Seeding Rates Early planting results in extra tiller development. To avoid excessive growth, wheat is planted with one-third less seed then normal (see chapter 7, “Small Grain Seeding Rates For NC” in this production guide: www.smallgrains.ncsu.edu/_Pubs/PG/Srates.pdf). Restrict No-Tillage to the Piedmont In the NC piedmont this system has worked well with no-till planting. In the NC coastal plain and tidewater, very early no-till planting is not recommended. This is due to the slower growth that young wheat plants exhibit when planted no-till in eastern NC. This slower growth combined with possible wireworm and Hessian fly damage can reduce no-till yields even with the insecticidal seed treatments. On the other hand, very early planting in eastern NC has worked well with conventional tillage. Very-Early-Planted Variety Testing Tests across NC have shown that when the five steps outlined above are followed, wheat yields are similar to those achieved when planting at the normal recommended times shown in Figure 5-1: (www.smallgrains.ncsu.edu/_Pubs/PG/Pdates.pdf) using normal seeding rates (Tabl e 7-1: www.smallgrains.ncsu.edu/_Pubs/PG/Srates.pdf) and untreated seed. The very early planting even at the lower seeding rates allows the wheat time to tiller and often to produce a thicker stand than would normally be achieved (Photo 6-1). Yield results from trials conducted in Salisbury in 2009, 2010, 2011, and 2012 are shown in Table 6-1. Very Early Planting 17 Photo 6-1. Even though the very-early-planting-system uses 30% less seed, it often results in denser stands due to greater tillering in the fall. Left: The very-early-planting system at Plymouth, NC, planted on October 8, 2009. Right: Normal wheat planting system also at Plymouth, planted on October 29, 2009. The photographs were taken on February 17, 2010. Table 6-1. Very-early-planting variety test results from Salisbury, NC. The tests were planted on Sept. 29 using reduced seeding rates, GauchoXT, and only late-heading varieties. Late-Heading Wheat Varieties Yield (bu/acre) 2012 2011 2010 2009 Pioneer 26R20 109.0 DynaGro 9053 105.9 Pioneer 26R12 101.3 131.5 99.7 106.1 DynaGro Shirley 101.2 133.2 102.8 Branson 98.1 131.3 Pioneer 25R32 93.6 127.2 UniSouth Genetics 3665 91.2 133.5 92.2 102.4 AgriPro Coker 9436 91.1 130.3 86.9 85.5 VA Merl 90.6 133.2 92.9 Pioneer 26R15 90.6 82.4 99.0 Southern States 8302 90.4 132.6 97.1 102.6 ARS Appalachian White 66.6 DynaGro V9713 128.2 90.0 99.5 NC Yadkin 122.6 NC Neuse 118.4 87.5 86.4 UniSouth Genetics 3725 91.1 VA Roane 85.8 93.5 18 Very Early Planting 7. Small Grain Seeding Rates for North Carolina Randy Weisz and Ron Heiniger Wheat, Triticale, and Hulled Barley The results from ten wheat seeding-rate studies (conducted in Virginia and North Carolina) are shown in Figure 7-1. In these studies certified seed with a high germination rate was planted on different sites at seeding rates ranging from about 0.6 million to over 2.0 million seeds per acre. All ten tests were planted using conventional tillage near the recommended dates shown in Figure 7-2 for North Carolina. In Figure 7-1 yield is shown relative to the highest yielding seeding rate in each test. So, for each of the ten tests, the yield at the highest seeding rate is set to 0. As seeding rates range from 0.9 to 1.6 million seeds per acre, average yield (blue line in Figure 7-1) only varies by about 1 bushel per acre! The grey box in Figure 7-1 shows a broad range in seeding rates (1.1 to 1.5 million seeds per acre) that produced the highest average yields. As seeding rates drop below that, yield becomes highly variable. In some years when the fall weather was warm, these lower seeding rates yielded well. In other years when the weather did not favor rapid tillering, low seeding rates resulted in up to a 12 bushel loss. Seeding rates above 1.5 million seeds per acre generally resulted in lower yields probably due to higher disease levels and lodging. Seeding Rates 19 Figure 7-1. Ten wheat seeding-rate studies conducted using certified seed with high germination (at least 90 percent), planted into conventionally tilled seed beds and planted near the dates shown in Figure 7-2. Yield is shown as a percent of that at the highest seeding rate. Seeding rates ranged from 0.6 to 2.3 million seeds per acre. The grey box represents suggested seeding rates based on these tests. J J J J J J J J J J J J J J J J J J J J J J J J J J J J J J J J J J -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 Yield (bushels per acre from optimum) Seeding Rate (million seeds per acre) Timely Planted Yield The grey area in Figure 7-1 shows an optimal range in seeding rates from 1.1 to 1.5 million seeds per acre. This range in seeding rates is similar to what other researchers have found. For example, Syngenta Seed has been doing wheat seeding-rate studies in the NC coastal plain. They report that optimum yields are frequently reached for most growers at around 1.1 million seeds per acre. They recommend 1.5 million seeds per acre for growers interested in intensive management. The intensive wheat management guide from the Virginia Polytechnic Institute recommends planting 1.31 to 1.52 million seeds per acre. Many growers think about small grain seeding rates in terms of pounds of seed per acre. Table 7-1 shows how 1.31 and 1.52 million seeds per acre can be converted into more familiar units. The lower rate of 1.31 million seeds per acre is equal to 30 seeds per square foot. The higher rate (1.52 million seeds per acre) is the same as 35 seeds per square foot. But, the number of pounds of seed needed to reach these targets depends on seed size. A large seeded variety may only have 10,000 seeds per pound compared to a small seeded variety that could have up to 15,000 seeds in a pound. This makes planting a single number of pounds of seed per acre problematic. Table 7-1 shows that the ideal seeding rate of 1.31 to 1.52 million seeds per acre can range all the way from 87 to 152 pounds of seed per acre depending on seed size! It is important that growers consider seed size when selecting seeding rates based on pounds per acre! Most drills have tables that indicate how to set the seed metering mechanism for a given seeding rate in pounds per acre. Ideally, if the seed size is known (for certified seed it is often printed on the tag attached to the bag), a grower could use Table 7-1 to determine the pounds of seed to plant per acre, and use the drill manufacturer’s information to find the proper drill setting to plant that number of pounds per acre. However, experience has shown that using these factory settings can result in large over- or under-seeding. For example, in 2001 we calibrated a John Deere no-till drill to plant the correct seeding rate (based on Table 7-1) for 15 wheat varieties, each of which had half the seeds treated with GauchoXT seed treatment and half untreated. To produce the same seeding rate for each variety, we had to change the drill setting from 27 all the way to 45—depending on the variety and 20 Seeding Rates Murphy Asheville Jefferson Mt Airy Mocksville Salisbury N. Wilkesboro Hickory Forest City Gastonia Concord Albemarle Monroe Jackson Springs Reidsville Oxford Arcola Siler City Raleigh Sanford Smithfield Fayetteville Laurinburg Whiteville Willmington Longwood Warsaw GoldsboroKinston Rocky Mt Murfreesboro Elizabeth City Plymouth New Holland Bayboro Morehead City Hofmann Forest Lumberton Sept 25 - 30 Sept 30 - Oct 5 Oct 5 - 10 Oct 10 - 15 Oct 15 - 20 Oct 15 - 20 Oct 20 - 25 Oct 15 - 20 Oct 25 - 30 Oct 25 - 30 Oct 20 - 25 Oct 25 - 30 Oct 30 - Nov 4 Oct 30 - Nov 4 Oct 30 - Nov 4 Figure 7-2. The start of wheat and triticale planting dates for NC. Timely planting for oats and barley is five to ten days earlier. seed treatment! Our experiment revealed that the drill settings required to achieve the correct wheat-plant population varied widely among varieties and seed treatments and this variation was not reflected in the manufacturer’s charts. The best way to ensure a correct small grain seeding rate is to calibrate the drill for the specific seed being planted. The most accurate way to calibrate is to base seeding rates on the desired number of seed per drill-row foot. This number does not vary across seed sizes or change depending upon seed treatments. Table 7-1 gives target seeding rates in terms of seeds per drill-row foot across a range of drill-row widths. For example, Table 7-1 shows that if a grower has a drill with 7.5-inch row spacing, the correct seeding rate is between 19 and 22 seeds per drill-row foot (assuming planting is on time, the seed has at least 90 percent germination, and planting is into a conventionally tilled seed bed). Hulless Barley Hulless barley seed is more easily damaged then hulled seed. Consequently, hulless barley must be planted at higher seeding rates than traditional hulled varieties. Dr. Wade Thomason, the corn and small grain specialist at Virginia Tech, gives this guideline: When using high-quality hulless barley seed with at least 90 percent germination, the target seeding rate is 2.2 million seeds per acre or 50 seeds per square foot when using a conventionally tilled seedbed. Table 7-2 gives hulless barley seeding rates across a range of seed sizes and drill row widths. Seeding Rates 21 Table 7-1. Wheat, triticale, and hulled barley seeding rates for conventionally tilled seed beds planted on time using a target of 1.31 to 1.52 million seeds per acre with 90 percent germination as a standard. These rates need to be increased by 20 percent for no-till. Million seeds per acre: 1.31 1.52 Seeds per square foot: 30 35 Seed size (seeds per pound) Pounds of seed per acre 10,000 131 152 11,000 119 138 12,000 109 127 12,500 105 122 13,000 101 117 14,000 94 109 15,000 87 101 Drill row spacing (inches) Seed per drill-row foot 6 15 17 7 18 20 7.5 19 22 8 20 23 Table 7-2. Hulless barley seeding rates for conventionally tilled seed beds using a target of 2.2 million seeds per acre or 50 seeds per square foot with 90 percent germination as a standard assuming planting is on time. These rates need to be increased by 20 percent for no-till. Million seeds per acre: 2.2 Seeds per square foot: 50 Seed size (seeds per pound) Pounds of seed per acre 10,000 218 11,000 198 12,000 182 12,500 174 13,000 168 14,000 156 15,000 145 Drill row spacing (inches) Seed per drill-row foot 6 25 7 29 7.5 31 8 33 Oats and Rye Oats should be planted at 2 bushels per acre. Rye should be planted at 1 to 1.5 bushels per acre. Low Germ Seed The seeding rates shown in Tables 7-1 and 7-2 are for seed with at least 90 percent germination. Some certified seed, and most bin-run seed, will not have germination rates this high. Consequently, the seeding rates in these tables need to be increased for seeds with a germination rate lower than 90 percent. Table 7-3 shows the increase required for different levels of germination. Low Germ Seed Example If a grower wants to plant wheat at the higher seeding rate of 1.52 million seeds per acre and has a variety with 12,500 seeds per pound, Table 7-1 indicates the recommended seeding rate would be 122 pounds of high germ seed per acre. A germ test indicates the seed has a germination rate of only 80 percent. Table 7-3 shows the seeding rate will have to be increased by 13 percent to compensate. Thirteen percent of 122 pounds is 16 pounds. So the grower would plant 122 + 16 = 138 pounds of this seed with lower germ. What About Planting Late? In NC, small grains frequently follow soybeans that are harvested in October or November. This results in small grains being planted after the optimal planting dates. When wheat, triticale, hulled or hulless barley is planted after the dates shown in Figure 7-2, seeding rates should be increased by 4 to 5 percent for each week planting is delayed. Planting Depth Wheat varieties have semidwarf genes that reduce overall plant height. These also reduce the chances of seedling emergence if the seeds are placed too deep. Conversely, a shallow planting can result in uneven germination due to dry soil. Small grain seeds should be planted 1 to 1.5 inches deep when soil moisture levels are adequate and slightly deeper if moisture is deficient. Seeding Rates for No-Till No-till planting causes special challenges related to uneven seed beds and surface residue. Although seeds should still be planted 1 to 1.5 inches below the soil surface, be aware that changes in the depth of any residue and undulations in the soil’s surface may result in the drill missing the targeted seeding depth. When residue from the previous crop is unevenly distributed, achieving a uniform and correct planting depth can be difficult. Where the residue is uneven, the planting depth may be too shallow under high residue and too deep in areas of light residue. This can result in thin stands and excessive risk of winterkill. Preparation for no-till small grains begins with evenly distributing crop residues while harvesting the previous crop. To obtain a uniform stand, start with a seeding rate that is 20 percent higher than what is recommended for conventional tillage (Tables 7-1 and 7-2). When no-till drilling, stop periodically and make sure that the planting depth is uniform and correct. 22 Seeding Rates Table 7-3. Increase in seeding rates required for lower germination seed. Seed germination Increase seeding rates in Tables 7-1 and 7-2 by: 85% 6% 80% 13% 75% 20% 70% 29% 65% 38% Drill Calibration The manufacturer’s seeding rate chart that comes with commercial drills is a rough estimate of how many pounds of seed will be planted at a given setting. Experience with wheat seed has shown that this estimate can be off by as much as 100%. The best way to be sure the correct seeding rate is being planted is to calibrate the drill for each seed lot being grown. Three methods for calibrating a drill are d e m o n s t r a t e d i n a n o n l i n e v i d e o at www.smallgrains.ncsu.edu/drill-calibration.html. The simplest drill calibration method is outlined below: 1. Select the desired seeding rate. For example, if planting on-time, using conventional tillage, and high quality seed, a recommended wheat seeding rate would be 1.3 million seeds per acre. 2. Use Table 7-1 to convert seeds per acre to seeds per drill row foot. For example, if planting at 1.3 million seeds per acre with a drill that has 7.5- inch row spacing, Table 7-1 indicates that converts to 19 seeds per foot of row. 3. Hook a tractor to the drill, put at least several inches of seed in the hopper, and use the setting that is a “best guess” at what is needed to get the correct seeding rate. 4. Run the drill for 20 to 30 feet over firm ground (like a dirt road) with minimum down pressure on the openers and closing wheels so that the seed is exposed and easy to see. 5. Pick a drill row and count the number of seed in two feet. 6. If there are too many seed, lower the setting and try again. If there are too few seed, increase the setting and repeat. For example, if the target is 19 seed per drill row foot, but the drill dropped 24, the setting needs to be reduced. 7. Repeat step 6 until the number of seed being dropped is correct. Record the setting needed for this seed lot. Special Considerations for Broadcast Seeding Broadcast seeding often results in uneven seed placement in the soil, which results in uneven emergence and stands. Seeds may be placed as deep as 3 to 4 inches, where many seeds will germinate but will not emerge through the soil surface. Other seeds may be placed very shallow or on the soil surface. These seeds often do not survive due to dry soil or winter damage. The uneven stands from broadcasting often result in lower yields compared with drilling. One method of improving stand uniformity is to broadcast seed in two passes across the field using half the seeding rate for each pass. The second pass is made perpendicular to the first pass. Although this method should improve stand uniformity, it also increases the time required to seed the field. Because plant establishment potential is reduced and seed placement is not uniform, seeding rates should be increased for broadcast seeding. Increase broadcast seeding rates by 30 percent to 35 percent over drilled seeding rates. Seeding Rates 23 Online VIDEO: How to Calibrate a Drill www.smallgrains.ncsu.edu/drill-calibration.html Broadcasting wheat with fertilizer is a fast way to seed small grains. Take precautions to ensure that the seed is uniformly blended with the fertilizer and that the fertilizer-seed mixture is uniformly applied. Seed should be mixed with fertilizer as close to the time of application as possible and applied immediately after blending. Allowing the fertilizer-seed mixture to sit after blending (longer than 8 hours), particularly with triple super phosphate (0-46-0) or diammonium phosphate (18-46-0), results in seed damage (reduced germination) and, subsequently, a poor stand. Considerations for Overseeding Small grains may be planted by overseeding in standing, unharvested crops. To follow soybeans, seed as the first soybean leaves begin to drop. Following cotton, seed just before defoliation. The small grain can be injured or killed if it is growing when a desiccant is used. If no desiccant is used, seed when the leaves begin to drop. The leaves will form a mulch that conserves moisture and enhances germination. The success or failure of overseeding depends on available moisture. Overseeding before a rainfall event improves the chances of success. Wheat and rye tend to emerge better when overseeded than do oats or barley. Test the Results: Check the Stands No matter how you plant the seed, be sure to check the stands shortly after emergence. Is the stand uniform? Determine the number of healthy seedlings present in a square foot. There should be 22 to 25 seedlings (or more, if planted late). If the stand is uniform and the plant density is correct, then the planting was successful. References Some materials in this chapter were adapted from: Alley, Brann, Stromberg, Hagood, Herbert, Jones. 1993. Intensive Soft Red Winter Wheat: A Management Guide (Publication 424-803). Virginia Polytechnic Institute, Cooperative Extension Service. Ambrose. 1998. Wheat On-Farm-Test Report. Beaufort County Cooperative Extension Service & NC State University. (www.smallgrains.ncsu.edu/_Pubs/OnFarm/BFT1998.pdf). Ambrose. 1999, 2000, & 2001. Wheat On-Farm-Test Report. Beaufort County Cooperative Extension Service & NC State University. Joseph, Alley, Brann, Gravelle. 1985. Row Spacing and Seeding Rate Effect on Yield and Yield Components of Soft Red Winter Wheat. Agron. J. 77:211-214. Lee, Herbek. 2009. A Comprehensive Guide to Wheat Management in Kentucky (Publication ID-125). Lexington, KY: University of Kentucky College of Agriculture, Cooperative Extension Service. Smith, Wood, Grandy, Williams, Smith, Powell. 2006. NE Expo Wheat Field Day Test Results. Perquimans, Pasquotank, Currituck, Chowan, Gates, and Camden County Cooperative Extension Service & NC State University. (www.smallgrains.ncsu.edu/ _Pubs/OnFarm/NEX2006.pdf) Weisz, Love, Tarleton. 2011. Southern Coastal Plains Small Grains Extension Program 2011 Test Report. NC State University. (www.smallgrains.ncsu.edu/_Pubs/OnFarm/SCNC2011.pdf) Weisz, Love, Tarleton. 2012. Southern Coastal Plains Small Grains Extension Program 2012 Test Report. NC State University. (www.smallgrains.ncsu.edu/_Pubs/OnFarm/SCNC2012.pdf) 24 Seeding Rates 8. Nitrogen Management for Small Grains Randy Weisz and Ron Heiniger Nitrogen management is one of the most important keys to successful small grain production. It is also one of the easiest management strategies to misuse, resulting in yield reductions and environmental damage. To achieve optimum yields, follow the correct N guidelines for applications in the fall, winter, late January to early February, and at growth stage 30 (which usually occurs in March). Chapter 9, “Nutrient Management for Small Grains” (www.smallgrains.ncsu.edu/_Pubs/PG/Nutrient.pdf), discusses soil testing and management of all other nutrients. We discuss N management first and separately because there is no soil test useful for making N recommendations in NC, and because of its importance for small grain production. Fall: Preplant Nitrogen When Planting Near the Recommended Dates When planting on time, 15 to 30 pounds preplant N per acre are generally sufficient to promote maximum growth and tillering. This application can be very important for high yields because N stress early in the season will prevent adequate tillering. When small grains follow soybeans or peanuts, enough carryover N may be present to meet small grain fall requirements. Unfortunately, the availability of carryover N is difficult to predict and there is no method for testing for available N in the fall. In many years and locations, the N released from a previous legume crop many not be available until the following spring or even summer, which is too late to support fall tillering. Consequently, unless experience with specific fields indicates otherwise, a small amount of preplant N is recommended even when following soybeans or peanuts. When Planting Later Than Recommended Research has shown that late-planted small grains may not respond to preplant N applications. When temperatures are too low to promote tillering, preplant N cannot be taken up by the plants and is easily leached out of the soil. Adding preplant N even at high rates cannot simulate tillering in cold soils. Consequently, when planting late, application of preplant N to small grains might be skipped. Early Planting System In chapter 6, “Beating Soybean Harvest: A Very Early W he a t - P l a n t i n g S y s t em” ( o n l i n e a t : www.sm a l l g r a ins. n c s u . e du/_Pubs /PG/ VeryEarly.pdf), we introduced a system for very early wheat planting. Small grains planted before the optimal planting dates risk freeze damage. So when planting very early, it is important to follow all the recommendations given in that chapter. Additionally, preplant N application to early planted small grains promotes increased tillering, but this can also increase the risk of freeze damage. While applying N to early planted small grains will often result in better looking stands, research has shown that it generally does not increase yields. Consequently, preplant N should be reduced or eliminated when planting earlier than the recommended dates (see chapter 5, "Small Grain Planting Dates, in this production guide: www.smallgrains.ncsu.edu/_Pubs/PG/Pdates.pdf). No-Till Preplant N management for no-till small grains is similar to conventional-till with a couple of minor differences. Many no-till growers find that their pre-plant N rates need to be on the high end of the recommended range. Therefore, when planting during the recommended planting dates, consider as much as 30 lbs of preplant N per acre. Growers using the early planting system may also want to Nitrogen Management 25 consider applying 15 to 30 lb N per acre preplant, particularly in conditions where corn or sorghum residue is heavy. Winter: Rescue Applications Nitrogen management during the winter consists of making sure the crop does not become N deficient. Small grains under N stress in the winter can lose tillers, which may reduce yield. Indications of a possible N deficiency are a pale green color, thin and poorly developing stands, and leaching rains after planting. An application of 15 to 30 pounds N per acre can help to green the crop back up if these symptoms occur. This rescue application needs to be made when daytime temperatures are expected to be above 50oF. Late January and Early February: Last Chance to Grow More Tillers Late January to early February is the time to determine if the crop has enough tillers to optimize yield. This is a very important decision. Apply N in January or February only if tiller densities are less than 50 tillers per square foot. If N is not needed, applying N in January or February results in increased risk of freeze damage, disease, lodging, and reduced yield. If tillering is low, however, an early application of N can help to stimulate further tiller development in the last few weeks before growth stage 30, resulting in higher yield and profit. The following guidelines will help you decide whether to apply N in late January or early February. Guidelines for Wheat If at the end of January or in the first week of February, wheat looks as thick as that shown in Photo 8-1, it is well on the way to being a potentially high yielding field. This wheat has about 100 well-developed tillers per square foot and should not have any N applied until growth stage 30. A well-developed tiller is one with at least three leaves. The wheat in Photo 8-2 is a “medium” density stand with about 50 tillers per square foot. It also is well on the way to being a good yielding crop, and should not have any N applied until growth stage 30. The wheat in Photo 8-3, however, is poorly tillered and only has about 20 tillers per square foot. It has a low yield potential and needs more tillers to develop in February. It should have 50 to 70 pounds N fertilizer applied in late January or early February. A second N application should be made to finish this crop off at growth stage 30. Thin stands like those shown in Photo 8-3 need timely weed management, but should not have 2,4-D applied because 2,4-D may inhibit tiller development. Growers also need to scout for cereal leaf beetle in April, as these insect pests are often attracted to thin wheat stands. Wheat stands that are thicker than the stand shown in Photo 8-3 but not as well developed as that shown in Photo 8-2 also need an early N application. Such a field will yield best with 40 to 50 pounds of N fertilizer applied in late January or early February and a second N application to finish the crop off at growth stage 30. This approach to stand evaluation is shown in Figure 8-1. In late January and early February, a “tiller” is considered to be any stem that has three or more leaves. Rough estimates of tiller density can 26 Nitrogen Management Online VIDEO: Counting Tillers to Optimize N Rates www.smallgrains.ncsu.edu/tiller-counting.html be made by comparing a wheat field with Photos 8-1 through 8-3, or more exactly by counting tillers. To determine tiller density, count well-developed tillers (those with at least three leaves). Ignore small tillers that have only one or two leaves. Do not be concerned with differences between the main plant and younger side tillers. Just count any stem with at least three leaves as a tiller. The final count will include main plants, tillers, and side tillers. Count all the tillers that have at least three leaves in a yard of row. Do this in several places and take an average. Tiller density is then computed as follows: Tillers per square foot = (tillers per yard of row) × 4 (row width in inches) Example: If in five counts of tillers in a yard of row the average was found to be 102 tillers per row and the row spacing is 7.5 inches, then tiller density is: 102 × 4 ÷ 7.5 = 54.4 tillers per square foot. An alternative is to mark out a square foot of ground and count all the tillers in that area that have at least three leaves. Do this in several places and calculate the average. Guidelines for Oats, Barley, Triticale, and Rye Research on counting tillers to time N applications for these crops has not been done. Growers will need to rely on past experience to judge when splitting N will benefit oat, barley, or triticale stands that are thin in late January to early February. Growth Stage 30: The Most Important Time to Apply Nitrogen! During growth stage 30, small grains switch from producing tillers, to starting reproductive growth. In the first phase of reproductive growth, the stem elongates, the plant gets taller, and the small grain crop begins to take up large amounts of N. The Nitrogen Management 27 Photo 8-1. Well-tillered – about 100 tillers per square foot. Photo 8-2. Medium-tillered – about 50 tillers per square foot. Photo 8-3. Poorly-tillered – about 20 tillers per square foot. Apply 50 - 70 lb N as soon as possible Does the wheat have at least 50 tillers per square foot ? (see Photo 8-2) YES NO NO YES Is the wheat very thin with only 20 to 30 tillers per square foot ? (see Photo 8-3) Do not apply N until growth stage 30 Apply 40 - 50 lb N as soon as possible Figure 8-1. Late January to early February guidelines for wheat N fertilization. future grain head is formed at this stage (although still underground), and N stress at this growth stage will affect head formation and result in smaller heads. Since N at this stage of development is critical and larger amounts of N are needed to satisfy N requirements, the bulk of spring N fertilizer needs to be applied at this stage. A typical fertilizer application rate at growth stage 30 for wheat is 80 to 120 pounds N per acre (minus any that was applied in late January or early February to stimulate tillering). However, optimal N rates can vary dramatically from field to field and year to year depending on the weather, the crop’s yield potential, and the presence of carry-over N from previous crops. Tissue testing at growth stage 30 is one way to help fine-tune N rates to maximize economic return. The Wheat Tissue Test Tissue testing for wheat N rate recommendations was developed in VA and has been available for many years. It uses the N concentration detected in a tissue sample collected at growth stage 30. Research in NC, however, has shown that the VA recommendations can overestimate the required N for our growing conditions. Therefore, a new system has been developed that is helpful in optimizing wheat N fertilizer rates specifically for NC producers. This research indicates that N rates based on a tissue test are most reliable for wheat grown on well-drained soils. The test should not be used on poorly-drained organic soils. This new system and subsequent recommendations are especially helpful when N prices are high and growers need to minimize input costs without compromising yield. For assistance with growth stage 30 tissue testing, NC producers can contact an NC Department of Agriculture & Consumer Ser vices (NCDA&CS) r egional agr onomi st (www.ncagr.gov/agronomi/rahome.htm) or county Extension agent (www.ces.ncsu.edu). Here are the steps and information needed to determine the optimum N rate with a tissue test. Step 1: Determine the Growth Stage As temperatures warm in spring, tillering stops and the wheat crop’s demand for N increases rapidly. This is the beginning of stem elongation, often referred to as growth stage 30. Because growth stage 30 is the best time to apply N fertilizer to winter wheat, it is important to know when the crop reaches this stage. The calendar date when wheat reaches growth stage 30 is influenced by variety, planting date, and environmental conditions. Early-heading varieties can reach it in February. Late-heading varieties may not reach growth stage 30 until mid-March. One clue that the wheat is at growth stage 30 is that the plants start to stand up and get taller. However, the best way to tell if wheat is at growth stage 30 is to pull up several plants and split the stems down their centers all the way to the base where the roots grow. Prior to growth stage 30, the growing point will be at the very bottom of the stem just above the first roots. At growth stage 30, the growing point will have moved ½-inch up the stem (Figure 8-2). After growth stage 30, it will move further up the stem and be above the soil surface. Tissue samples can be taken when the 28 Nitrogen Management Growing Point First Roots Figure 8-2. Wheat stem cross-section at growth stage 30. The growing point will be dark green, about 1/8-inch long, look like a tiny pine cone, and prior to growth stage 30 be at the very base of the stem next to the first roots. At growth stage 30 it will have moved 1/2-inch up the stem. growing point is between ¼- and ¾-inch above the base of the stem. Step 2: Collect Tissue and Biomass Samples Two pieces of information are needed to determine the optimum N rate: percentage of tissue N and biomass. At growth stage 30, take a tissue sample by cutting wheat plants from 20 to 30 representative areas in the field. The plants should be cut ½-inch above the ground. Soil and dead leaf tissue must be removed and the cuttings placed in a paper bag labeled “tissue.” The percentage of N is detected in this tissue sample. For the most accurate N rate recommendation, an estimate of above-ground biomass is also required. At one representative location in the field, cut all the wheat along a 36- inch section of row, remove any soil and weed tissue, and place the entire sample in a second paper bag labeled “biomass.” The biomass or weight is detected in this sample. The two samples should be shipped to the NCDA&CS Agronomic Division immediately. If samples have to be stored for more than 24 hours after collection, they must be dried to prevent spoilage and loss of biomass. Step 3: Use the Chart and Table with the Plant Report An example of the NCDA&CS plant report is shown in Figure 8-3. In this example, the dry weight of the biomass cut from the 36-inch length of row was 36 grams and the tissue N percentage was 3.5. Using the biomass dry weight and the N percentage values, N fer tilizer recommendations are determined using either the BLUE, RED or GREEN line in Figure 8-4. Low biomass wheat fields use the BLUE line. Medium biomass fields use the RED line. High biomass fields use the GREEN line. To determine which line to use, consult Table 8-1. Find the biomass value on the left side of Table 8-1. Look across the table to find the drill row spacing used in the field. The intersection of the correct drill-row column and the dry-weight row indicates which colored line to use. If the drill row spacing in the SHOP field (Figure 8-3) is 6 inches, then Table 8-1 indicates the GREEN line should be used to get a N fertilizer rate recommendation. If the wheat was broadcast seeded, there will be no drill rows to sample and Table 8-1 cannot be used. In broadcast fields, the biomass dry weight in a square yard will need to be estimated. Low biomass fields are defined as those with less than 84 grams of dry biomass per square yard. Medium biomass Nitrogen Management 29 Figure 8-3: NCDA&CS Plant Analysis Report. Table 8-1. Line color to use in Figure 8-4 for N rate recommendations. Dry weight in 36 inches of row (g) Row spacing in inches 5 6 7 8 ≤ 10 15 20 25 30 35 ≥ 40 fields are defined as those with 84 to 157 grams dry weight per square yard. High biomass fields have more than 167 grams dry weight per square yard. Step 4: Don’t Let a Sulfur or Potassium Deficiency Rob Wheat Yield Potential Sulfur-deficient wheat does not assimilate N fertilizer efficiently so it is important to make sure adequate sulfur (S) is available at growth stage 30. In addition to the percent N content, the NCDA&CS plant report also gives levels of other plant nutrients, including S. These levels can be checked against the critical values shown in Table 8-2. A tissue S content less than 0.25 percent, or an N-to-S ratio greater than 15, indicates that S is limiting and the wheat will likely benefit from an application of 20 to 30 lb S per acre at growth stage 30. North Carolina coastal plain wheat producers who have deep sandy soils can also use the growth stage 30 tissue test to optimize potassium (K) fertilizer inputs. This is especially important for producers who may have skipped or reduced preplant potash for their wheat and for the following double-cropped soybeans. Ideally, growers who have wheat on deep sandy soils should submit both a growth stage 30 tissue sample and a diagnostic soil sample from the same field. Tissue K levels of less than 2 percent indicate that the wheat crop is deficient. If the soil sample also shows low K-index levels, K will be needed as soon as possible for the wheat crop, and certainly before the subsequent soybean crop is planted. Wheat Tissue Test Examples Low Wheat Biomass Example The plant report shows the biomass sample weighed 8 grams and the tissue sample had a N content of 3.5%. The wheat was planted in 6-inch rows. Table 8-1 indicates the BLUE line in Figure 30 Nitrogen Management 0 10 20 30 40 50 60 70 80 90 100 110 120 2.0 2.5 3.0 3.5 4.0 4.5 5.0 GS-30 N Recommendation (lb/acre) Percent N In Tissue At GS-30 N Recommendations For Low biomass wheat Medium biomass wheat High biomass wheat Virginia tissue test Figure 8-4. Growth stage 30 N rate recommendations based on the new NC wheat tissue test. Table 8-2. GS-30 whole plant tissue sample nutrient sufficiency levels. Nutrient P K Mg S B Zn Mn Cu ------ % ------ ------ ppm ------ Sufficient level 0.25 2 0.1 0.25 3 12 20 3 8-4 is the correct one to use as this is a low biomass wheat field. Finding 3.5% on the horizontal axis of Figure 8-4 and using the BLUE line show the recommended N fertilizer rate is 71 lb per acre. Thin wheat fields could result from late planting or from fall temperatures that were too low to promote tillering and growth. In fields like this, the VA (dashed line) and NC system (BLUE line) make very similar N rate recommendations. Medium Wheat Biomass Example The plant report shows the biomass sample weighed 25 grams and the tissue sample had a N content of 3.5%. The wheat was planted in 7-inch rows. Table 8-1 indicates the RED line in Figure 8-4 is correct for N fertilizer rate recommendations as this is a medium biomass wheat field. Finding 3.5% on the horizontal axis of Figure 8-4 and using the RED line show the recommended N fertilizer rate is 46 lb per acre. In medium biomass fields, the VA system (dashed line) tends to overestimate the N fertilizer rate required to optimize yield and economic return, especially for wheat with N content greater than 3.5%. High Wheat Biomass Example The plant report shows the biomass sample weighed 36 grams and the tissue sample had a N content of 3.5%. The wheat was planted in 7-inch rows. Table 8-1 indicates the GREEN line in Figure 8-4 is correct for N fertilizer rate recommendations as this is a high biomass wheat field. Finding 3.5% on the horizontal axis of Figure 8-4 and using the GREEN line show the recommended N fertilizer rate to be 0 lb per acre. High biomass fields can result from high carry-over N from a previous crop, fall manure application, or unusually warm fall and winter weather that promoted excess tillering. In these fields, the VA system (dashed line) overestimates the growth stage 30 nitrogen fertilizer rate. Oats, Barley, Triticale, and Rye Research on using tissue samples to optimize N requirements for these crops has not been done. Use Table 8-3 to determine the crop's total spring N requirement. Nitrogen Management 31 Table 8-3. Spring N recommendations for oats, barley, triticale, and rye. Region Spring N Fertilizer (pounds per acre) Oats Barley Triticale Rye Coastal Plains 100 100 120 80 Piedmont & Mountains 80-100 80 120 80 Tidewater 100 100 120 80 9. Nutrient Management for Small Grains Carl Crozier, Ron Heiniger, and Randy Weisz Routine Soil Testing to Prevent and Manage Nutrient Deficiencies Soil testing before planting is an essential component of a small grain fertility management program. Different fields can vary so widely in pH and nutrient levels that it is impossible to predict optimum application rates without soil test results. It is much more economical to prevent yield losses associated with nutrient deficiencies than to try to correct them once visible symptoms appear. Producers should sample each field once every two to three years at the same time of the year, preferably in the early fall. Often this is done before a corn or cotton crop, which tends to be more sensitive to applied nutrients than small grains. However, if you suspect a nutrient problem, then sample more frequently before a small grain crop and use that information to adjust nutrient applications. Sample boxes, information sheets, test results, and recommendations are provided free of charge by the Agronomic Division of the NCDA&CS, and guidelines for soil testing procedures can be found in another Extension publication: SoilFacts: Careful Soil Sampling – The Key To Reliable Soil Test Information (www.soil.ncsu.edu/ publications/Soilfacts/AG-439-30). Diagnostic Soil Sampling and Plant Tissue Analysis When abnormal growth or plant color is observed, it is often useful to obtain diagnostic samples to determine if there is a nutrient deficiency. If samples are collected to diagnose an observed problem rather than for routine purposes, then separate samples should be submitted to represent the surface soil (0 to 4 inches) and the subsoil (4 to 8 inches). Tissue analysis can determine whether an adequate amount of fertilizer has been applied or if a particular nutrient is limiting crop growth. Plant tissue analysis is particularly useful in determining a crop’s need for mobile nutrients, such as nitrogen, sulfur, and boron; and for diagnosis of deficiency symptoms for manganese, copper, or zinc. To take a tissue test, clip a handful of plants above the ground with 8 to 10 samples collected from both the problem area and a corresponding area of normal growth. When taking diagnostic samples, both soil samples and plant tissues from the affected "bad" area and a nearby unaffected "good" area should be submitted for analysis to the NCDA&CS diagnostic laboratory. Soil pH and Lime Recommendations Proper pH is critical in obtaining good crop growth and yield. Small grains grow best when the pH is near the target level for each soil class. If pH is too low, soluble aluminum and acidity can limit root growth and nutrient uptake. If pH is too high, micronutrients such as manganese, iron, copper, and zinc can become unavailable. Stunted growth, nutrient deficiency symptoms, and low yield are the most common problems associated with soil pH levels that are not maintained in the proper range. Often nutrient deficiencies are the result of low or high pH rather than a lack of adequate amounts of the nutrient in the soil. Ideal soil pH levels vary based on soil type. Target levels are 6.0 for mineral soils, 5.5 for mineral organic soils, and 5.0 for organic soils. When the soil pH is below these targets, apply lime as early as possible in the production year to allow time for neutralizing soil acidity. Liming rates and the type of lime applied cannot be determined based on soil pH alone; they also depend on residual soil acidity, residual credit for recently applied lime, and measurement of available magnesium. For more information see SoilFacts: Soil Acidity and Liming for Agricultural Soils 32 Nutrient Management (www.soil.ncsu.edu/publications/Soilfacts/ AGW-439-50/SoilAcidity_12-3.pdf ). Phosphorus Recommendations Phosphorus (P) plays a key role in germination and early plant growth, promotes winter hardiness, stimulates the growth of the wheat kernel, and has a role in determining when the plant reaches maturity. Phosphorus Deficiency Symptoms Purpling of the leaf margins and bottom leaf surfaces of the lower plant leaves and purpling of the leaf sheaths at the stem’s base are symptoms of P deficiency. Slow growth or stunting is another sign of P deficiency. Phosphorus-deficient plants are slow to mature, and green heads are often found in spots in the field at harvest. Deficiency symptoms are often found on waterlogged, cool soils in late winter or early spring. Phosphorus Fertilizer Rates As noted previously, a good soil test is the best way to determine fertilizer requirements. The following P recommendations are made only as guidelines and should not replace soil testing as the primary means of determining crop nutrient needs. A wheat crop yielding 40 bushels per acre typically requires 40 pounds of P2O5 (25 pounds in the seed and 15 pounds in the straw). Mineral soils, such as those found in the NC coastal plain and piedmont, bind P and prevent it from leaching. Heavy organic soils do not bind P, resulting in a movement of P to the lower soil horizons or to drainage waters. Soils high in clay content, such as those found in the piedmont, bind P very tightly, making it unavailable to the crop. Consequently, both heavy organic soils and soils high in clay content often test low in available P even though high amounts of P fertilizer are applied every year. Care must be taken on these soils to apply P in a way that limits the interaction between the P fertilizer and the soil. Because animal wastes are high in P, soils where heavy applications of animal waste have been applied will have high levels of available P. Table 9-1 shows the recommended rates for P fertilizer in the different regions and major soil types of the state. Phosphorus Placement and Timing Phosphorus should be broadcast on the soil just before planting. Growers farming heavy organic or clay soils should limit the amount of soil-fertilizer contact (and thus reduce nutrient binding), which means little to no tillage should occur after a P application. Potassium Recommendations Potassium (K) influences grain quality (including test-weight) and oil content, prevents lodging, and plays an important role in drought and disease tolerance. Potassium Deficiency Symptoms The most common deficiency symptom for K in small grains is stunted growth and early lodging. Plants with a K deficiency will have low vigor, poor drought or disease tolerance, and reduced kernel size. Under severe K deficiency, the leaf tip and margins on the lower leaves will bronze and eventually turn yellow and die. Deficiency symptoms are more likely on deep sandy soils or soils that are waterlogged and compacted. Potassium Fertilizer Rate A wheat crop yielding 40 bushels per acre typically requires 64 pounds of K2O (16 pounds in the seed and 48 pounds in the straw). Because so much of the K in the plant is in the straw, most of it will be recycled in the soil. Most of the agricultural soils in NC have adequate to high levels of available K. In particular, soils where animal waste has been applied will be high in available K. The exception to this rule is that available K is low on sandy soils in the NC coastal plain and tidewater. Sandy soils do not bind K, so the K leaches below the root zone. Nutrient Management 33 Potassium Placement and Timing Potassium should be broadcast just prior to planting. On sandy or very sandy soils with a high leaching potential, K should be applied in two applications, half at planting and the other half just prior to growth stage 30 when N is applied. There is no benefit to applying K to a growing crop after growth stage 31. 34 Nutrient Management Table 9-1. Critical macronutrients for small grain production. Element Common deficiency symptoms Common fertilizer forms 1 Basis for fertilizer rate Suggested rates per acre if soil test data are not available2 Notes Phosphorus (P) Stunting, purpling on margins of lower leaves or on leaf sheaths, delayed maturity Granular monoammonium phosphate (MAP, 11-52-0) Granular diammonium phosphate (DAP, 18-46-0) Liquid ammonium phosphate (10-34-0) Soil test Coastal plain mineral soils: 0 to 30 lbs P2O5 Tidewater organic soils low P index: 30 to 50 lbs P2O5 Piedmont clay soils, shallow topsoil: 30 to 40 lbs P2O5 Limit the amount of soil-fertilizer contact on heavy organic or clay soils. Potassium (K) Lower leaf tip and margin burn, weak stalks, lodging at harvest, small ears, slow growth Potassium [plus chloride (muriate 0-0-60), sulfate, nitrate, hydroxide, or magnesium sulfate] Soil test Sandy or very sandy soils: 50 to 60 lbs K2O Organic soils (only if K is deficient): 50 to 60 lbs K2O Mineral or clay soils: (only if K is deficient): 50 to 60 lbs K2O On deep sand, apply just before planting or split apply at planting and at growth stage 30. Calcium (Ca) Terminal and root tip damage, dark green, weakened stems, ear disorders Lime, calcium sulfate (gypsum) Soil test Apply lime at recommended rate. Generally OK if limed to target pH. Magnesium (Mg) Interveinal chlorosis in older leaves, leaf curling, margin yellowing Dolomitic lime, magnesium sulfate (epsom salt), potassium magnesium sulfate, magnesium oxide Soil test, tissue analysis If needed: 20-30 lb Mg Generally OK if dolomitic lime used. Sulfur (S) Yellowing of young leaves, small spindly plants, slower growth and maturation Elemental sulfur; sulfate [plus ammonium, calcium (gypsum), magnesium (epsom salt), potassium, potassium magnesium]; Ammonium thiosulfate; Sulfur-coated urea Tissue analysis or soil criteria Sandy soils low in S: 15 to 25 lb S Deficiency likely if sandy surface is 18+ inches deep. 1 This table does not list all available chemical forms of fertilizers or recommend use of any specific form. Percent chemical analyses included are examples only, and may not reflect the composition of any specific commercial source. 2 Soil samples should be taken to avoid underestimating or overestimating actual needs. Sulfur Recommendations Sulfur (S) increases kernel weight, kernel size, grain protein, yield, and test-weight. Sulfur is required for the production of chlorophyll and many enzymes involved in the utilization of N. Consequently, a small grain crop must have adequate amounts of S to use N fertilizer property. Sulfur Deficiency Symptoms Symptoms of S deficiency include yellowing of young leaves, small spindly plants, slowed growth, and delayed maturation. Sulfur deficiency looks very much like N deficiency except that with S deficiency the young leaves at the top of the plant are the first to turn yellow. Sulfur deficiency symptoms usually occur in patchy spots across the field. Generally, S deficiencies are only found on deep sandy soils. However, in recent years, S deficiency symptoms have occurred in clay and organic soils during cool, wet weather when the plant is small. Periodic checks in the late winter and early spring can help identify fields with S deficiency. Sulfur Fertilizer Rate A wheat crop yielding 40 bushels per acre typically requires 10 pounds of elemental S (4 pounds in the seed and 6 pounds in the straw). While most of the agricultural soils in NC will have adequate to high levels of available S, sandy soils with low levels of organic matter usually are deficient in S because S is water soluble and easily leached. On sandy, S deficient soils, 15 to 25 pounds S per acre can be applied at planting or with the N sidedress. Sulfur should be applied before jointing to avoid crop damage and increase the likelihood of an economic response. Calcium and Magnesium Recommendations Calcium (Ca) deficiency symptoms include terminal and root tip damage, dark green stems, weakened stems, and poor ear formation. Magnesium (Mg) deficiency symptoms include interveinal chlorosis in older leaves, leaf curling, and yellowing of the leaf margins. Generally, Ca and Mg levels are maintained through dolomitic lime applications. If deficiencies occur and no pH change is desired, then sulfate forms such as gypsum (calcium sulfate) or epsom salts (magnesium sulfate) can be applied at the rates recommended in Table 9-1. Micronutrient Management Due to expense and the potential for toxicity, applications of micronutrients (including copper, manganese, and zinc) are generally not made to small grains unless they are specifically recommended by a soil test or if specific deficiencies are identified. Common problems often found in wheat in NC include manganese deficiencies on overlimed soils and copper deficiencies on organic soils. Copper Recommendations Proper levels of copper (Cu) in the plant enhance protein content of the kernel and grain yield. Copper Deficiency Symptoms Common Cu deficiency symptoms include stunting, leaf tip or shoot die-back, and poor upper leaf pigmentation. Perhaps the best way to diagnose a Cu deficiency is by observing the leaf tip. "Pigtailing" or "corkscrewing" of the leaf tip is a sign of Cu deficiency. Organic soils are naturally low in Cu, and often deficiency symptoms can be found in plants grown in these soils, particularly when the plant and root system are small. Wheat is very sensitive to Cu deficiency and will be one of the first crops to show symptoms. Copper Fertilizer Rate A wheat crop yielding 40 bushels per acre typically requires 0.04 pounds of elemental Cu per acre (0.03 pounds in the seed and 0.01 pounds in the straw). Table 9-2 shows the rate of Cu to use when a soil test detects a low level or when deficiency symptoms are noted. Growers should take care to avoid the over-application of Cu fertilizers since Nutrient Management 35 high concentrations of Cu can be toxic to the plant. Timing a Copper Application The recommended time to apply Cu is preplant. This avoids the high cost of Cu chelates, eliminates the chance of leaf burn, and allows a much longer residual effect. However, if deficiency symptoms occur, a foliar spray can be applied at much lower rates than are recommended for soil applications. Usually, Cu chelates or organic dusts are recommended for foliar application. Do not apply Cu after jointing. Manganese Recommendations Proper levels of manganese (Mn) in the plant enhance plant growth and the production of chlorophyll. 36 Nutrient Management Table 9-2. Critical micronutrients for small grain production. Element Common deficiency symptoms Common fertilizer forms 1 Basis for fertilizer rate Suggested rates per acre if soil test data are not available2 Notes Copper (Cu) Stunting, leaf tip/shoot dieback, poor upper leaf pigmentation Copper sulfate, copper oxide, copper chelates Soil test, tissue analysis If deficient: apply 0.25 lb Cu to foliage with 0.50 lb of hydrated lime, or 2-8 lb3 Cu to soil. Boron (B) Leaf thickening, curling, wilting; reduced flowering/ pollination Boric acid, borax, solubor, borates Tissue analysis Avoid toxicity, apply only as needed. Iron (Fe) Interveinal chlorosis of young leaves Ferrous sulfate, ferric sulfate, ferrous ammonium sulfate, iron chelates Tissue analysis Manganese (Mn) Upper leaves pale green or streaked Manganese sulfate, manganese oxide, manganese chelate, manganese chloride Soil test, tissue analysis Coastal plain, sandy soil or any soil with Mn index less than 25: 10 lb Mn If deficient: apply 0.5 lb Mn to foliage, or 10 lb Mn to soil. Overliming decreases availability. Zinc (Zn) Decreased stem length (rosetting), mottling-striping, interveinal chlorosis Zinc sulfate, zinc oxide, zinc chelates, zinc chloride Soil test, tissue analysis If deficient: apply 0.5 lb Zn to foliage, or 6 lb Zn to soil. 1 This table does not list all available chemical forms of fertilizers or recommend use of any specific form. Percent chemical analyses included are examples only, and may not reflect the composition of any specific commercial source. 2 Soil samples should be taken to avoid underestimating or overestimating actual needs. 3 NCDA guidelines are 2 lb Cu/ac or 6 lb CuSO4/ac for mineral soils, 4 lb Cu/ac or 12 lb CuSO4/ac for mineral-organic soils, and 8 lb Cu/ac or 24 lb CuSO4/ac for organic soils. Manganese Deficiency Symptoms Manganese deficiency symptoms include stunting, gray specks in the leaf, and pale to almost whitish upper leaves or streaked yellowing (interveinal chlorosis) of the upper leaves. Manganese deficiency can be distinguished from a Mg deficiency in that Mn affects the upper leaves while Mg affects the lower leaves. Manganese deficiencies commonly occur in overlimed soils (pH greater than 6.5 on mineral soils or greater than 6.1 on mineral-organic or organic soils) with low cation exchange capacity. A common situation where Mn deficiencies are noted is the over-limed areas at the ends of the field where the spreader truck turned or where lime was stockpiled. Manganese Fertilizer Rate A wheat crop yielding 40 bushels per acre typically requires 0.25 pounds of elemental Mn (0.09 pounds in the seed and 0.16 pounds in the straw). Sandy soils in the NC coastal plain are typically low in available Mn. Table 9-2 shows the rate of Mn to use when soil test levels are low or when deficiency symptoms are noted. Timing of Manganese Fertilizer Application The best time to apply Mn on soils with low test levels is preplant. However, to correct a deficiency if the soil pH is high, use a foliar application. Manganese is commonly supplied as manganese sulfate, manganese oxide, and manganese chelates or organic complexes. Manganese chelates and organic complexes are recommended only for foliar application due to soil reactions that tend to convert the Mn to unavailable forms. Application of foliar fertilizers may have to be repeated several times to correct severe deficiency symptoms on fields that have been overlimed. Once wheat is jointing, consider whether response to fertilizer is likely to outweigh crop damage due to traffic. Zinc Recommendations Zinc (Zn) deficiency symptoms include decreased stem length (rosetting), mottling, and interveinal chlorosis. Zinc deficiencies are most common if the soil pH is greater than 6.5 and the soil phosphorus index is greater than 75. As with other micronutrients, recommended rates (Table 9-2) are lower for foliar applications, but residual effects are greater with soil applications. Special Consideration for No-Till Production Before a field is placed in 100 percent no-till production, it should be soil tested and brought to target pH and optimum nutrient levels. Once adequate fertility levels are achieved throughout the root zone, no-till production can begin. Long-term no-till studies suggest that yields and soil fertility can be maintained even though lime and fertilizer are applied to the soil surface without incorporation. Routine soil samples in established no-till fields should be collected to a depth of 4 inches. Use of starter fertilizers containing N and P are more important in no-till production because plant development is delayed. Special Consideration for Precision Agriculture Currently, precision agriculture is being used for three primary reasons: (1) to identify areas in fields with different pH or soil test indexes, and vary lime and fertilizer rates accordingly; (2) to monitor and map crop yield and moisture content; and (3) to document material applications, including fertilizers and pesticides. The cost of collecting grid soil samples or using a yield monitor must be returned by decreasing the amounts of lime or fertilizer applied, increasing crop yield, reducing negative environmental impacts, or by some combination of these benefits. Growers are more likely to increase profits by using precision farming practices in situations where pH or fertility levels are limiting wheat yields. An examination of the variability in soil pH or fertility within a field should indicate the potential for increasing crop yield through variable-rate lime or fertilizer applications. If at least a fourth of the field area has soil nutrient indexes Nutrient Management 37 below 25, or pH levels below the target value for that crop and soil class, then it is likely that precision farming practices will increase wheat yields and profits. Special Consideration for Animal Wastes and Sewage Sludge Animal waste and sewage sludge can be excellent sources of nutrients and organic matter for a wheat crop. Organic forms of P can move deeper in soils than do inorganic fertilizer sources. Consequently, they can be advantageous in no-till or conservation tillage systems. When applying animal waste as a fertilizer material for wheat, all amendments should be tested before application to determine optimum application rates. Soils that are being fertilized with waste materials should be tested to determine nutrient levels. The amount of waste material applied should be based on the need for desirable nutrients, such as P or K, and the requirement that levels of P, Zn, Cu, cadmium, lead, and mercury should not exceed prescribed limits. Producers should rotate applications as much as possible to obtain nutrient benefits while minimizing excess nutrient and toxic metal accumulation. If you use lime-stabilized sludge or poultry litter, monitor the soil pH carefully to prevent overliming and possible Mn deficiency. Applications of animal waste are most effective when made prior to planting a small grain crop. However, topdress applications of poultry or swine manure can be done in January or early February with good results. Several good publications on application of animal waste and/or sludge can be found online: www.soil.ncsu.edu/publications/ extension.htm . 38 Nutrient Management 10. Insect Pest Management for Small Grains Dominic Reisig, D. Ames Herbert Jr., Gaylon Ambrose, and Randy Weisz Insect management can be critical to the economic success of a small grains enterprise, and growers should be aware of the various insects and management strategies and tactics. These techniques can help you prevent and detect some potentially serious insect problems before significant loss occurs. Aphids Aphids are small sucking insects that colonize small grains early in the season and may build up in the spring or fall. They injure the plants by sucking sap or by transmitting the barley yellow dwarf virus (BYDV). BYDV is a persistent virus that can be retained by the aphid for weeks and can be transmitted in minutes to a few hours of aphid feeding. Although the exact relationship between aphid numbers and direct yield loss is unknown, aphids must be very abundant before injury from sap-removal occurs. However, low aphid abundance early in the fall can result in high BYDV occurrence in winter cereals. Aphid flights in the fall from grasses surrounding cereals pose the most serious threat for this disease. Predicting aphid flights is difficult; flights are generally initiated from cues such as temperature, sunlight, and increasing daylength. Flights generally decrease as precipitation, relative humidity, and wind speed increase. Life Cycle Two species of aphids predominate in small grains: the English grain aphid (Photo 10-1) and the bird cherry-oat aphid (Photo 10-2). However, several others, such as the corn leaf aphid (Photo 10-3) and the greenbug (Photo 10-4), may be found occasionally. These aphids are described in Insect and Related Pests of Field Crops, AG-271 (http:// i p m . n c s u . e d u / AG 2 7 1 / s m a l l _ g r a i n s / small_grains.html). Aphids' high reproductive rate enables their populations to quickly build up to levels that can cause economic loss. However, aphid populations are usually kept in check by weather Insect Pest Management 39 Photo 10-1. English grain aphid. Photo by M. Spellman. Photo 10-2. Bird cherry oat aphid. Photo 10-3. Corn leaf aphid. Photo by Jack Kelly Clark. conditions and biological control agents, such as lady beetles, parasitic wasps, syrphid fly maggots, and fungal pathogens, which are often abundant in small grains. Management Aphids can occur throughout the growing season. In early-planted small grains, especially barley, low levels of aphids in the fall may transmit an infection of BYDV that can cause symptoms later in the season. Using a tolerant or resistant variety is an excellent management tactic. A list of the current wheat varieties that ar e r esistant to BYDV ( w w w. s m a l l g r a i n s . n c s u . e d u / _Mi s c / _VarietySelection.pdf) is available on the NC Small Grain Production Website (www.smallgrains.ncsu.edu). Insecticides (either as seed treatments or as a foliar application) to control aphids in the fall are generally not recommended. There are several situations, however, in which the use of insecticides can be beneficial. In areas with a chronic BYDV history, early-planted small grains may benefit from preventive neonicotinoid insecticide seed treatments (such as Gaucho, Cruiser, or NipsIt INSIDE). This may be important in the NC piedmont, as a recent study demonstrated that BYDV incidence can increase when wheat is no-till planted into corn residue. An alternative to using an insecticidal seed treatment is to make a foliar application of a long-residual pyrethroid insecticide at or before three- to four-leaf stage wheat. BYDV symptoms are easier to recognize in the spring than the fall. When aphid populations are relatively low in the fall, an insecticide application is justified only if BYDV is anticipated and freezing weather is not expected for at least one week. As cold weather begins, populations quickly decline. Scouting Scouting for aphids requires searching plants or examining heads on 10 samples taken at locations scattered across each field. Each sample should consist of all plants in 1 foot of row or 10 heads, depending on plant stage. For foliage examination, counting aphids on each sample is not feasible; instead, use a simple estimation technique. Initially, the scout must "calibrate" by visually establishing a mental picture of aphids on 1 row foot and then counting aphids over the entire plant to determine the actual number. After several repetitions of this exercise, aphid counting is no longer needed because a calibrated mental image is available. This mental image is then used to visually estimate populations in field scouting. Head-infesting aphids are similarly estimated, except in this instance the calibration exercise is done by using heads rather than whole plants. Threshold Aphids may become much more abundant in the spring than the fall. However, because plants are actively growing in the spring, they can support many more aphids without injury. Also, spring-transmitted BYDV usually does not seriously affect small grains. Consequently, the thresholds for applying insecticides are much higher in the spring compared to those for the fall (see Table 10-1). Armyworm Armyworm infests small grains, usually wheat, from late April to mid-May. They can cause serious defoliation, injury to the flag leaf, and also cause head drop. Armyworm populations fluctuate greatly 40 Insect Pest Management Photo 10-4. Greenbug. Photo by Alton N. Sparks, Jr., University of Georgia. from year to year and across areas of NC. Typically, the northeastern and mid-coastal counties experience the most consistent armyworm problems Life Cycle Armyworm moths are one of the first moths to become active during the spring. Moths prefer to lay eggs on various grasses, and small grains are very attractive. Thick planting, narrow row spacing, and high N rates promote dense and lush growth, which is conducive to high armyworm infestation. Young armyworm larvae are pale green, yellowish, or brown and have a habit of looping as they crawl. When they become larger (1 to 1½ inches), they are greenish-brown with pale white and orange stripes running down their bodies; the head is honeycombed with faint dark lines (Photo 10-5). The armyworm is described in Insect and Related Pests of Field Crops, AG-271 (http://ipm.ncsu.edu/ AG271/small_grains/small_grains.html ). Armyworm is the only caterpillar found in large numbers in small grains. They are active at night, hiding under plant litter (such as old corn stalks) and at the base of wheat plants during daylight hours. After dark, they feed on foliage from the bottom of the plant upward. As they eat the lower foliage or as it is destroyed by leaf pathogens, the armyworm larvae feed higher, eventually reaching the flag leaf. If populations are high, large caterpillars may also feed on the stem just below the head. Management Management of armyworm is based on scouting, thresholds, and resulting application of insecticides when necessary. Infestations of armyworms are not easily detected by casual observation because caterpillars hide during the day. Fortunately, several signs of armyworm infestation occur, and caterpillars can also be monitored if the correct technique is used. Blackbirds (grackles and red-winged blackbirds) commonly search for armyworms in small grains. Any field with significant bird activity should be scouted. Signs of armyworm leaf feeding and caterpillar droppings can also be good indicators. Feeding is sometimes inconspicuous because small caterpillars do not eat much and feeding signs are often concentrated on the lower part of the plant. When caterpillar Insect Pest Management 41 Photo 10-5. Armyworm. Photo by M. Spellman. Table 10-1. Aphid thresholds for small g grains in the fall and spring. Fall Spring Plant Height (inches) After heading 3 - 6 4 - 8 9 - 16 20 aphids per row foot, and BYDV has been a chronic problem or is expected, and cold weather is not forecast for at least one week. aphids per row foot 25 aphids per head and 90% of heads infested, or 50 aphids per head and only 50% of the heads infested 100 200 300 populations are high, droppings may be seen easily but should not be confused with weed seed. Scouting Fields should be scouted for armyworms in May when caterpillars are normally small. Thorough scouting should not be done until the caterpillars are at least 3/8-inch long because populations of small worms are difficult to estimate accurately and often die out. Once caterpillars reach 3/8-inch or more in length, take at least 5 samples per field (10 samples in larger fields of 20 acres and more) by examining all the wheat in 3 feet of one row. Look for and count the caterpillars in litter around the base of plants and under old crop residue. Pay special attention to fields in which birds are active. Fields should be scouted weekly until a treatment or no-treatment decision is made. Re-infestation of caterpillars in May after a successful insecticide application does not occur. Threshold The economic threshold is 6 half-inch or longer caterpillars per square foot. The threshold changes to 12 caterpillars per square foot when grain is near maturity. Cereal Leaf Beetle Cereal leaf beetle, a native to Europe and Asia, was first detected in Michigan in 1962. Since then, it has spread throughout most of the Midwestern and Eastern United States and has become a significant pest of VA and NC small grains. This insect can become very numerous in small grain fields, and the larvae may reduce grain yield by eating the green leaf tissue. Preferred small grain hosts for the larvae are wheat, oats, and barley, although the adults will feed on corn, wild grasses and all other cereals. Life Cycle Adult beetles (Photo 10-6) are about 3/16-inch long and have metallic looking, bluish-black heads and wing covers. The legs and front segment of the thorax are rust-red. Adults overwinter in grasses, ground litter, or other debris, within wooded areas, or in other protected sites in the vicinity of last season’s grain fields. In the spring, they emerge when the temperature is 48 to 50°F to feed, mate, and lay eggs in small grain fields. Eggs (Photo 10-7) are elliptical, about 1/32 of an inch long, and yellow when newly laid, but later become darker to orange-brown and finally black before hatching. Most often the eggs are laid singly or end-to-end in short chains on the upper leaf surface between, and aligned with, the leaf veins. Egg laying occurs during March and into April with more larvae found in poorly tillered small grain fields. Females lay 100 to 400 eggs each. These eggs will hatch in about 5 days. Larvae (Photo 10-8) are slug-like and have yellowish bodies with heads and legs that are brownish-black. However, body coloration is usually obscured by a black globule of mucus and fecal matter held on the body, giving the larvae a shiny black, wet 42 Insect Pest Management Photo 10-6. Cereal leaf beetle adult. Photo 10-7. Cereal leaf beetle eggs. appearance. Larvae develop in 10 to 12 days. Peak larval populations occur in mid-April to early May. Upon reaching full size, they dig ½ to 2 inches into the ground and pupate. Pupation usually lasts 15 to 20 days. Injury to Small Grains Although adults will feed on young small grain plants, their feeding does not affect the plant's performance. However, larvae eat long strips of green tissue from between leaf veins and may skeletonize entire leaves (Photo 10-9), leaving only the transparent lower leaf tissue. Severely defoliated fields can take on a white "frosted" cast (Photo 10-10) as green tissue is lost on the upper leaves. Yield Reduction Leaf feeding indirectly reduces the plant's ability to make its food and limits reproductive growth, particularly if the upper leaves are destroyed. Larger larvae are by far the most damaging. Yield reductions of 10 to 20 percent are typical in infested commercial fields. Yield reductions of 45 percent have been observed when defoliation was near 100 percent and the damage occurred early in the heading period. Damage late in the head-fill period does not have a great impact. Scouting Method • Take samples at a minimum of 10 random sites in the interior of the field (avoid the edges). At each site, examine 10 stems for eggs and larvae. This will result in 100 stems per field being examined. • Eggs may be on the leaves near the ground. Record the number of eggs and larvae counted at each sample site and then calculate the total number of eggs and larvae found in the field. • If there are more eggs than larvae, scout again in five to seven days. This is important because egg mortality can be very high. A large number of eggs does not necessarily mean there will be a high larvae population. Insect Pest Management 43 Photo 10-8. Cereal leaf beetle larva. Photo 10-9. Wheat leaf damage caused by cereal leaf beetle larvae feeding. Photo 10-10. A wheat field severely damaged by cereal leaf beetle feeding. • If there are more larvae than eggs, there is no need to scout again. A decision about applying an insecticide for control can now be made. Threshold When the scouting results show that there are more larvae than eggs, peak egg laying has passed and it is the correct time to use the spray threshold. If there are 25 or more eggs plus larvae on 100 stems, the threshold has been met. Management Tips Cereal leaf beetle adults are attracted to dense highly-tillered wheat fields, but more larvae per tiller are found in poorly-tillered fields. Management practices that lead to densely tillered stands by mid- February can help to reduce the risk of having a cereal leaf beetle infestation. These practices include planting on-time, using high quality seed planted at recommended seeding rates, making sure that preplant fertility is adequate for rapid fall growth, and applying a split nitrogen application in February and March if additional tillering is needed in the spring. Cereal leaf beetle is easily controlled with low rates of many insecticides if they are applied when the threshold is met. Because only one generation hatches per year, if insecticides are applied based on the use of thresholds, one application will give adequate management. However, if insecticides are applied early before threshold levels are met (such as with top-dress nitrogen), reduced application rates may not be adequate. And even when full label rates are used, a second application may be required later in the season. Insecticides labeled for cereal leaf beetle control in small grains are listed in Table 10-2. To be most effective, insecticides must be applied by early head-fill, before the larvae cause significant yield-reducing defoliation. In making a choice about insecticides, consider the presence of aphids or armyworms. Both carbamates and pyrethroids kill aphid parasites and predators. Carbamates can sometimes allow a serious aphid increase. Therefore, a carbamate should not be applied against cereal leaf beetle if aphids are a potential threat. Carbaryl, beta-cyfluthrin, lambda-cyhalothrin, and zeta-cypermethrin provide excellent management, with good residual effects at least 14 days after treatment. Spinosad provides adequate management under normal situations, with minimal residual effects. Under heavy pressure situations, using spinosad is equivalent to doing nothing. 44 Insect Pest Management Table 10-2. Insecticides labeled for cereal leaf beetle management (2013). Although they may be as effective as the chemicals listed here, generic formulations are not listed nor are pre-mixed products with multiple insecticide classes. Insecticide Class Active Ingredient Trade Name Formulation/A Carbamates methomyl Lannate LV 1 to 2 pt Lannate SP 0.25 to 0.5 lb carbaryl Sevin brand XLR PLUS 1 pt Pyrethroids beta-cyfluthrin Baythroid XL 1.0 to 1.8 fl oz lambda-cyhalothrin Karate Z or Warrior II 1.92 fl oz Karate or Warrior 2.6 fl oz zeta-cypermethrin Mustang Max EC 1.6 to 4.0 fl oz Hessian Fly Why Has Hessian Fly Become a Problem? In recent years, numerous NC fields have suffered extensive losses because of Hessian fly infestations. Historically a wheat pest in the Midwest, changes in field-crop production including early planted wheat, increased adoption of no-tillage double-cropped soybeans, and the use of wheat as a cover crop for strip-tillage cotton and peanut production have permitted the Hessian fly to reach major pest status in NC. Hessian Fly Life Cycle The adult Hessian fly is a small, long-legged, two-winged insect that resembles a small mosquito (Photo 10-11). It is one of many species of gnat-sized flies that may be found in wheat fields. The female Hessian fly adult is reddish-brown and black in color and about 1/8-inch long. The slightly smaller males are brown or black. The elliptical eggs are very small and orange. Eggs are deposited singly or end-to-end in “egg lines” between the veins on the upper surface of the young leaves (Photo 10-12). Newly hatched larvae (maggots) are also orange for 4 or 5 days before turning white (Photo 10-13). As larvae mature, a translucent green stripe appears down the middle of the back. The maggot is about ¼ inch long when full grown. The maggot transforms into an adult fly inside a dark-brown case, or puparium, that resembles a flaxseed in size and shape. Newly formed puparia will be a lighter-brown color that transforms to a mahogany-brown color with age. Puparia or "flaxseeds” (Photo 10-14) are located under leaf-sheaths and usually below ground on young tillers or below the joint in older plants. Hessian fly can be found in small numbers in most wheat fields at harvest. If the wheat stubble is destroyed after harvest, the fly dies and the life cycle is broken (Figure 10-1). If, however, the wheat stubble is left in the field, the fly can survive as “flaxseeds” in the stubble through the summer. In late August and September, adults emerge from the “flaxseeds” and lay eggs on volunteer wheat or on early planted cover-crop wheat. A first generation can be completed on these plants, and the next generation adults emerging from cover-crop or volunteer wheat plants can lay eggs on wheat planted for grain in October and November, before Insect Pest Management 45 Photo 10-11. An adult Hessian fly. Photo 10-12. Hessian fly eggs. Photo 10-13. Large Hessian fly larvae. the weather turns cold enough to kill the adult flies. Often Hessian flies begin depositing eggs very soon after seedling emergence. Once Hessian flies are established on a new wheat crop, their eggs hatch within a few days and the tiny maggots migrate into the whorl of small wheat plants, ultimately locating below ground at the stem’s base, where they enter the pupal stage. While feeding, the larvae injure the plants by rupturing leaf or stem cells. They cause the plant to form an area of nutritive tissue around the base to enhance their feeding, which can result in tiller stunting and dieback. A heavy infestation on early-stage plants may greatly reduce plant stand. A new generation of adults usually emerges in March depending on the weather, lays eggs, and produces new larvae that migrate to the stem joints where they feed and cause further injury. This spring injury may kill the wheat, but usually only results in weakened stems, small heads, and poorly filled grain heads with low-quality kernels. Often, wheat lodges in seriously infested fields. 46 Insect Pest Management Photo 10-14. Hessian fly puparia or “flaxseed”. < No-till beans allows pupa to over-summer 3rd generation adults re-infect wheat plants Pupae overwinter in tillers Maggots kill fall tillers Maggot feeding causes lodging Summer Autumn Winter Spring Disking before beans kills pupae & ends the life cycle Pupae in wheat straw at harvest Eggs laid on volunteer wheat, grassy weeds or early planted cover-crop wheat 1st generation adults emerge in soybean fields & seek new host 2nd generation adults emerge & seek wheat planted for grain Figure 10-1. The Hessian fly life cycle. Management Rotation Because the Hessian fly life cycle depends largely on the presence of wheat stubble, rotations that prevent new wheat from being planted into or near a previous wheat crop’s stubble will be an effective way to prevent infestations. Avoid planting wheat into last season’s wheat stubble! Continuous no-tillage wheat, double-cropped with soybeans, may result in severe problems and should be avoided in Hessian fly problem areas. Additionally, since the Hessian fly is a weak flier, putting distance between the location of new wheat plantings and the previous season’s wheat fields can be a successful method of preventing new infestations. Although Hessian fly can become serious under other situations, most serious infestations occur when wheat is planted early into wheat stubble or into fields next to wheat stubble. Tillage: Disking wheat stubble after harvest effectively kills the Hessian fly. Planting soybean no-till into wheat stubble enhances Hessian fly survival by preserving the site where puparia spend the summer. Burning wheat straw will reduce puparia, but many puparia are found below the soil surface. Therefore, burning is not as effective as disking and is not recommended as a management method. Choosing Cover Crops Serious Hessian fly infestations have occurred where wheat for grain was planted near early-planted wheat for cover or where early-planted wheat was present for dove hunting. In cropping systems where cover crops are used, such as in strip-till cotton or peanut production, the use of other small grains besides wheat will reduce Hessian fly populations. Although Hessian fly can develop on grasses in more than 17 genera, some are more favorable hosts for egg laying and development. Oats, rye, and triticale are not favorable for Hessian fly reproduction and do not serve as a nursery, making these grains preferable over wheat for cover cropping in areas where wheat for grain is also produced. If triticale is used for cover cropping, varieties that are adapted to NC should be planted. Delayed Planting Because freezing temperatures kill Hessian fly adults, a traditional method for preventing Hessian fly infestation is to delay planting until after the first freeze (often called the fly-free date). This concept has not worked well in NC because an early freeze is not a dependable event. Often a “killing freeze” does not occur until December in many areas of NC, after most growers need to have wheat planted for agronomic purposes. There is no reliable fly-free date in North Carolina. Resistant and Tolerant Varieties Correct varietal selection is probably the most inexpensive and effective method of Hessian fly management (Photo 10-15). Many wheat varieties are advertised as having Hessian fly resistance. Unfortunately, in most cases, resistance is based on a single gene present in the variety that must match a gene in the Hessian fly. This resistance often works by causing cell death and fortification of the cell wall around the nutritive tissue where the Hessian fly feeds. To be effective in NC, wheat varieties must be specifically resistant to the local Hessian fly genotype. A list of the current wheat var i e t i e s that ar e r e s i s tant t o He s s ian f l y ( w w w. s m a l l g r a i n s . n c s u . e d u / _Mi s c / Insect Pest Management 47 Online VIDEO: Identifying & Managing Hessian Fly www.smallgrains.ncsu.edu/hessian-fly.html _VarietySelection.pdf) is available on the NC Small Grain Production Website (www.smallgrains.ncsu.edu). In most cases, varieties rated as having “good” resistance should provide enough protection to avoid economic losses due to Hessian fly. In areas with severe Hessian fly problems, however, the use of resistant and tolerant varieties may not be sufficient to prevent infestations from occurring. Systemic Se
Object Description
Description
Title | Small grain production guide |
Date | 2013-03 |
Description | 2013 (Revised March 2013) |
Digital Characteristics-A | 72.8 MB; 84 p. |
Digital Format |
application/pdf |
Pres File Name-M | pubs_serial_smallgrainproduction201303.pdf |
Full Text | Small Grain Production Guide Revised March 2013 Small Grain Production Guide Revised March 2013 Prepared by Randy Weisz, Crop Science Extension Specialist, NC State University With additional contributions from Gaylon Ambrose, County Extension Agent, Beaufort County Cooperative Extension Steve Bambara, Retired Entomology Extension Specialist, NC State University Christina Cowger, USDA–ARS, Plant Pathologist, NC State University Carl Crozier, Soil Science Extension Specialist, NC State University Wesley Everman, Weed Science Extension Specialist, NC State University Ron Heiniger, Crop Science Extension Specialist, NC State University D. Ames Herbert, Jr., Professor, Entomology, Virginia Polytechnic Institute David Jordan, Crop Science Extension Specialist, NC State University Paul Murphy, Small Grains Breeder, NC State University Dominic Reisig, Entomology Extension Specialist, NC State University Published by North Carolina Cooperative Extension Service College of Agriculture & Life Sciences North Carolina State University Acknowledgments This publication is supported in part by a grant from the NC Small Grain Growers Association, Inc. The association provides funds to supplement public appropriations and research programs at NC State University for the benefit of the small grain industry, general consumers, and the public at large. Contents 1. Small Grain Growth and Development . . . . . . 1 2. Wheat Enterprise Budgets . . . . . . . . 5 3. Small Grain Variety Selection . . . . . . . 9 4. To Plant or Drill: Does Row Spacing Matter? . . . . . 13 5. Small Grain Planting Dates . . . . . . . . 14 6. Beating Soybean Harvest: A Very Early Wheat-Planting System . . . 16 7. Small Grain Seeding Rates for North Carolina . . . . . 19 8. Nitrogen Management for Small Grains . . . . . . 25 9. Nutrient Management for Small Grains . . . . . . 32 10. Insect Pest Management for Small Grains . . . . . . 39 11. Insect Pests of Stored Small Grains . . . . . . 51 12. Small Grain Disease Management . . . . . . . 56 13. Small Grain Weed Control . . . . . . . . 70 1. Small Grain Growth And Development By Randy Weisz Small grains respond best to inputs when they are applied at specific growth stages. Therefore, it is important to understand how small grains develop so you can identify the different growth stages and properly time applications of pesticides, nitrogen, and other inputs. Small grain development can be divided into four phases: vegetative growth or tillering, stem extension, heading and flowering, and kernel formation and ripening. The specific growth stages associated with these phases have been described in several scales. The most popular scales are the Feekes and Zadoks stages of development (Table 1-1). Both scales will be described in this chapter, but we will use the Zadoks system in the rest of this production guide. Vegetative Growth And Tillering In NC, wheat is typically planted from mid-October through late November. Plants emerge about one week after planting (Feekes 1 or Zadoks 11, see Figure 1-1), and leaves begin to develop on the mainstem or shoot. When the fourth leaf unfolds, the first tiller starts to grow (Feekes 2 or Zadoks 21), and a new tiller is produced with every subsequent unfolding of a leaf on the mainstem. Tillering continues as long as the plants are healthy, unstressed, and the temperature is warm. Tillers are important because each tiller can only produce one grain head, and tillers that develop in the fall often produce the largest heads and contribute the most to crop yield. Tillering slows down or stops when winter weather turns cold. When the weather warms up again in late January or February, another brief period of further vegetative growth occurs when spring tillers can grow if nitrogen is available. In NC, tillering and vegetative growth usually end between late Febuary and mid-March (Feekes 4-5 or Zadoks 30). Growth And Development 1 Stem Extension During Feekes growth stage 4-5 or Zadoks 30, small grains switch from producing tillers to starting reproductive growth. In the first phase of reproductive growth, the stems extend and the plant grows taller. The growing point, which was below ground during tillering, moves upward through the elongating stem and begins the transition into what will become a head of grain. The first easily 2 Growth And Development Emergence Feekes 1 Zadoks 11 Three leaves Feekes 1 Zadoks 13 First Tiller Feekes 2 Zadoks 21 Three Tillers Feekes 2 Zadoks 23 Tillering Ends Feekes 4-5 Zadoks 30 Figure 1-1. Vegetative growth and tillering phase of wheat development. More details and pictures of these growth stages can be found online. First Joint Feekes 6 Zadoks 31 Flag Leaf Visible Feekes 8 Zadoks 37 Flag Leaf Ligule Visible & Boot Swollen Feekes 9 to 10 Zadoks 39 to 45 Boot Splitting Feekes 10 Zadoks 47 Figure 1-2. Stem extension. More details and pictures of these growth stages can be found online. detected sign that this has started is the appearance of the first node or joint at Feekes growth stage 6 or Zadoks 31 (see Figure 1-2). The joint is a small swelling of the stem that somewhat resembles a joint on a human finger. As the stem continues to develop, several joints may appear. Knowing this is important for the small grain producer: the developing grain head is always inside the stem just above the highest joint. That means that if the stem is damaged by being driven over, a freeze, or lodging, the developing head is also likely to be damaged. Additionally if liquid nitrogen fertilizer is applied after jointing, the developing grain head is almost always burned, resulting in potential yield reductions. The flag leaf is the last leaf to develop on the small grain plant. The growth stage when it first appears at the top of the stem is defined as Feekes 8 or Zadoks 37. As the flag leaf unfolds, the ligule or collar at the base of the leaf become visible at Feekes 9 or Zadoks 39. At this time the developing grain head is getting large enough that the stem containing it swells. This swelling is called the boot. As the grain head continues to grow it eventually causes the boot to split open at Zadoks 47. Heading and Flowering The plant starts the heading phase of development when the first spikelet has emerged from the boot at Feekes 10.1 or Zadoks 50. Over the next few days the grain head will fully emerge from the boot at Feekes 10.5 or Zadoks 58 (see Figure 1-3). About one week later, the head will begin to shed pollen as flowering begins. Kernel Formation A few hours after pollination, grain kernels begin to form. Dry matter starts accumulating in the kernels, and a clear to milky fluid can be squeezed from them. This is known as the milk stage of kernel formation. Forage harvest during the milk stage results in the best combination of nutrient quality and yield. With continued growth and water loss, the kernel content changes from a milky fluid to a doughy or mealy consistency. This is called the soft dough stage. At soft dough, the green color of the head begins to fade (Photo 1-1) and harvesting forage at this time results in maximum dry matter Growth And Development 3 ¾ Of Head Visible Feekes 10.4 Zadoks 56 Fully Headed Feekes 10.5 Zadoks 58 Flowering Feekes 10.51 to 10.53 Zadoks 60 to 68 Figure 1-3. Heading and flowering. More details and pictures of these growth stages can be found online. Photo 1-1. Soft dough. Feekes growth stage 11.2 or Zadoks 85. yield. When the water content of the kernels drops to about 30 percent, the plant loses most of the green color but the kernels can still be cut by pressing with a thumbnail. This is called the hard dough stage. This marks the end of all insect and disease pest management. When the kernels reach 13 to 14 percent moisture, the grain is harvest ripe (Photo 1-2). References Some materials in this chapter were adapted from these references: Alley, M. M., D. E. Brann, E. L. Stromberg, E. S. Hagood, A. Herbert, and E.C. Jones. 1993. Intensive Soft Red Winter Wheat: A Management Guide (Publication 424-803). Blacksburg: Virginia Polytechnic Institute, Cooperative Extension Service. Hilfliger, E. (Ed.). 1980. Wheat-documenta. CIBA-GEIGY, Technical Monograph. Basle, Switzerland: CIBA GEIGY Ltd Strand, L. 1990. Integrated Pest Management for Small Grains (Agricultural and Natural Resources Publication 3333). Oakland, CA: University of California Statewide IPM Project. 4 Growth And Development Table 1-1. Feekes and Zadoks scales of small grain development. Feekes Zadoks General Description Vegetative Growth & Tillering 1 10 1st leaf through coleoptile 12 2nd leaf unfolded 13 3rd leaf unfolded 2 21 Main shoot and 1 tiller 22 Main shoot and 2 tillers 23 Main shoot and 3 tillers 3 26 Main shoot and 6 tillers 4-5 30 Tillering ended, leaf sheaths strongly erected Stem Extension 6 31 1st node detectable 7 32 2nd node detectable 8 37 Flag leaf just visible 9 39 Flag leaf ligule visible 10 45 Boots swollen Heading and Flowering 10.1 50 1st spikelet visible through split boot 10.2 52 ¼ head emerged 10.3 54 ½ head emerged 10.4 56 ¾ head emerged 10.5 58 Head fully emerged 10.51 60 Start of flowering Kernel Formation 10.54 71 Milk stage - watery ripe 11.1 75 Milk stage - medium milk 11.2 85 Soft dough 87 Hard dough 11.3 91 Dry matter accumulation ends 11.4 92 Harvest ripe Photo 1-2. Harvest ripe. Feekes growth stage 11.4 or Zadoks 92. 2. Wheat Enterprise Budgets By Randy Weisz and Ron Heiniger In NC, wheat is grown in a double-cropped soybean production system. This allows the risk of crop failure to be spread across two harvests and increases income potential. A full-season soybean budget is included for comparison with wheat double-cropped bean production. At the wheat and soybean prices that the market has been offering in 2012 and 2013 this double-cropped system is highly profitable. The wheat budgets presented here are based on practices outlined throughout this production guide. If you have a smaller farm, smaller equipment, or use more inputs than assumed in these budgets, costs will be higher than those shown in the following tables. Please note that these budgets are for planning purposes only. Items for All Wheat Bean Budgets • Wheat and soybeans are planted with a Great Plains 22-foot wide no-till drill. • Pre-plant fertilizer to provide 27 pounds N, 70 pounds P2O5, and 100 pounds K2O per acre is applied by a commercial applicator as 152 pounds of diammonium phosphate (18-46-0) and 167 pounds of potassium chloride (0-0-60). • Lime is applied once every three years and is prorated across each season. • All herbicides, fungicides, insecticides, and top-dress N-fertilizer are applied using a HiBoy with a 90-foot boom. • A broadleaf herbicide is applied in February. • Top-dress N (100 pounds per acre) is applied in March as 30% N solution. • A fungicide is applied to the wheat between flag leaf and heading. • An insecticide is applied to the wheat either in March tank-mixed with top-dress N, or in April tank-mixed with the fungicide. • Wheat and beans are harvested by combine with a 30-foot wide header. • All soybeans are Roundup Ready planted no-till. • A herbicide application is made to the soybeans pre-plant to help prevent development of glyphosate resistance. • Glyphosate is applied post-emergence. • An insecticide is applied to all soybean acreage in August. • One-fourth of the land in production is rented at $100 per acre. Conventional-Till Wheat No-Till Beans Budget • In the fall, field preparation is made with two passes of a 30-foot-wide disk harrow, and one pass with a 29-foot-wide field cultivator. • Wheat is planted at 1.5 million seeds per acre (35 seeds per square foot) or about 2.4 bags of seed per acre. • Soybeans are planted at 160,000 seed per acre. No-Till Wheat No-Till Soybeans Budget • In the fall, field preparation is limited to one application of glyphosate applied pre-plant. • Wheat is planted at about 2.7 bags of seed per acre. • Soybeans are planted at 160,000 seed per acre. Full-Season No-Till Soybean Budget • This budget is identical to the double-cropped soybean budgets except that soybeans are planted in May and expected to yield more, no pre-plant N is applied, and the rates of P2O5, and K2O are reduced. Wheat Enterprise budgets 5 6 Wheat Enterprise budgets Table 2-1. No-till wheat and double-cropped no-till Roundup Ready soybean budget. Unit Quantity Price or Cost/Unit Total per Acre Your Farm 1. GROSS RECEIPTS Wheat BU 55 $8.00 $440.00 ___________ Soybeans BU 30 $14.00 $420.00 ___________ TOTAL RECEIPTS: $860.00 ___________ 2. VARIABLE COSTS Wheat seed BU 2.7 $15.00 $40.50 ___________ Soybean RR seed THOU. 160 $0.36 $57.60 ___________ Pre-plant fertilizer DAP LBS 152 $0.36 $54.72 ___________ Potassium chloride LBS 167 $0.32 $53.44 ___________ Commercial spreading ACRE 1 $6.00 $6.00 ___________ Top-dress N (30% solution) LBS 90 $0.62 $55.80 ___________ Lime (Prorated) TON 0.33 $48.50 $16.01 ___________ Herbicides for wheat ACRE 1 $21.54 $21.54 ___________ Herbicides for soybeans ACRE 1 $33.65 $33.65 ___________ Fungicides for wheat ACRE 1 $10.80 $10.80 ___________ Insecticides for wheat ACRE 1 $4.63 $4.63 ___________ Insecticides for soybeans ACRE 1 $11.85 $11.85 Crop insurance for wheat ACRE 1 $6.00 $6.00 ___________ Crop insurance for beans ACRE 1 $10.00 $10.00 ___________ Hauling wheat BU 55 $0.15 $8.25 ___________ Hauling soybeans BU 30 $0.15 $4.50 ___________ Tractor/Machinery ACRE 1 $25.48 $25.48 ___________ Labor HRS 1.35 $7.25 $9.79 ___________ Interest on Op. Cap. DOL $190.09 6.50% $12.36 ___________ TOTAL VARIABLE COSTS: $442.91 ___________ 3. INCOME ABOVE VARIABLE COSTS: $417.09 ___________ 4. FIXED COSTS Tractor/Machinery ACRE 1 $39.06 $39.06 ___________ TOTAL FIXED COSTS: $39.06 ___________ 5. OTHER COSTS Land rent ACRE 0.25 $100.00 $25.00 ___________ General overhead DOL $442.92 4.5% $19.93 ___________ TOTAL OTHER COSTS: $44.93 ___________ 6. TOTAL COSTS: $526.90 ___________ 7. NET RETURNS TO RISK AND MANAGEMENT: $333.10 ___________ Wheat Enterprise budgets 7 Table 2-2. Full-till wheat and double-cropped no-till Roundup Ready soybean budget. Unit Quantity Price or Cost/Unit Total per Acre Your Farm 1. GROSS RECEIPTS Wheat BU 55 $8.00 $440.00 ___________ Soybeans BU 30 $14.00 $420.00 ___________ TOTAL RECEIPTS: $860.00 ___________ 2. VARIABLE COSTS Wheat seed BU 2.4 $15.00 $36.00 ___________ Soybean RR seed THOU. 160 $0.36 $57.60 ___________ Pre-plant fertilizer DAP LBS 152 $0.36 $54.72 ___________ Potassium chloride LBS 167 $0.32 $53.44 ___________ Commercial spreading ACRE 1 $6.00 $6.00 ___________ Top-dress N (30% solution) LBS 90 $0.62 $55.80 ___________ Lime (Prorated) TON 0.33 $48.50 $16.01 ___________ Herbicides for wheat ACRE 1 $10.57 $10.57 ___________ Herbicides for soybeans ACRE 1 $33.65 $33.65 ___________ Fungicides for wheat ACRE 1 $10.80 $10.80 ___________ Insecticides for wheat ACRE 1 $4.63 $4.63 ___________ Insecticides for soybeans ACRE 1 $11.85 $11.85 Crop insurance for wheat ACRE 1 $6.00 $6.00 ___________ Crop insurance for beans ACRE 1 $10.00 $10.00 ___________ Hauling wheat BU 55 $0.15 $8.25 ___________ Hauling soybeans BU 30 $0.15 $4.50 ___________ Tractor/Machinery ACRE 1 $27.96 $27.96 ___________ Labor HRS 1.76 $7.25 $12.76 ___________ Interest on Op. Cap. DOL $183.59 6.50% $11.93 ___________ TOTAL VARIABLE COSTS: $432.47 ___________ 3. INCOME ABOVE VARIABLE COSTS: $427.53 ___________ 4. FIXED COSTS Tractor/Machinery ACRE 1 $43.93 $43.93 ___________ TOTAL FIXED COSTS: $43.93 ___________ 5. OTHER COSTS Land rent ACRE 0.25 $100.00 $25.00 ___________ General overhead DOL $432.47 4.5% $19.46 ___________ TOTAL OTHER COSTS: $44.46 ___________ 6. TOTAL COSTS: $520.86 ___________ 7. NET RETURNS TO RISK AND MANAGEMENT: $339.14 ___________ 8 Wheat Enterprise budgets Table 2-3. Full-season no-till Roundup Ready soybean budget. Unit Quantity Price or Cost/Unit Total per Acre Your Farm 1. GROSS RECEIPTS Soybeans BU 37 $14.00 $518.00 ___________ TOTAL RECEIPTS: $518.00 ___________ 2. VARIABLE COSTS Soybean RR seed THOU. 160 $0.36 $57.60 Fertilizer ___________ Pre-plant P2O5 LBS 65 $0.41 $26.65 ___________ Pre-plant K2O LBS 83 $0.55 $45.65 Commercial spreading ACRE 1 $6.00 $6.00 ___________ Lime (Prorated) TON 0.33 $48.50 $16.01 ___________ Herbicides for soybeans ACRE 1 $33.65 $33.65 ___________ Insecticides for soybeans ACRE 1 $11.85 $11.85 Crop insurance for beans ACRE 1 $10.00 $10.00 ___________ Hauling soybeans BU 37 $0.15 $5.55 ___________ Tractor/Machinery ACRE 1 $10.72 $10.72 ___________ Labor HRS 0.61 $7.25 $4.42 ___________ Interest on Op. Cap. DOL $98.14 6.50% $6.38 ___________ TOTAL VARIABLE COSTS: $234.48 ___________ 3. INCOME ABOVE VARIABLE COSTS: $283.52 ___________ 4. FIXED COSTS Tractor/Machinery ACRE 1 $17.69 $17.69 ___________ TOTAL FIXED COSTS: $17.69 ___________ 5. OTHER COSTS Land rent ACRE 0.25 $100.00 $25.00 ___________ General overhead DOL $234.48 4.5% $10.55 ___________ TOTAL OTHER COSTS: $35.55 ___________ 6. TOTAL COSTS: $287.72 ___________ 7. NET RETURNS TO RISK AND MANAGEMENT: $230.28 ___________ 3. Small Grain Variety Selection Randy Weisz, Paul Murphy, and Christina Cowger Keep Up to Date! Small grain varieties generally have the highest yields and milling quality during the first couple of years after their release. Consequently, the varieties grown on a farm should change over time. This makes it important to keep up to date on newly released varieties and how they are doing in NC. Plant newer varieties on small acreage to assess performance. Plant the most consistent performers on most of the available cropland, and phase out the older varieties showing signs of succumbing to disease and insect pressures. Getting Unbiased Information The best source of unbiased public and private wheat variety performance information for NC is the Wheat Variety Performance and Recommendations SmartGrains Newsletter (www.smallgrains.ncsu.edu/ _Misc/_VarietySelection.pdf), which is released every July at NC State University and prepared by Randy Weisz (in the Crop Science Department at NC State) and Christina Cowger (USDA– Agricultural Research Service, Plant Pathology Department). This newsletter is based on the Official Variety Test Report or OVT (www.ncovt.com), and additional Cooperative Extension variety testing projects around NC. This newsletter groups wheat varieties into four categories: above average yielding, above average but less consistently yielding, average yielding, and below average yielding. It also gives heading date and pest resistance information about each wheat variety. The best source of unbiased variety performance information for other small grains is the OVT (www.ncovt.com) produced annually by the Crop Science Department at NC State University. It is also updated every July. Additionally, producers in counties adjacent to VA may find the Virginia Official Variety Test Report to be valuable (http://pubs.ext.vt.edu/category/ grains.html). Guidelines for Specific Variety Selection Avoid Varieties Not Adapted to North Carolina All small grain varieties that have been in the OVT for more than one year are usually good candidates for production. Avoid investing in varieties that have not been entered into these tests because they usually are not adapted to NC’s growing conditions and may be highly susceptible to local diseases or mature too late to follow with double-cropped soybeans. Only varieties that have been in the OVT for at least two years are included in the Wheat Variety Performance and Recommendations SmartGrains Newsletter. Plant at Least Three Varieties Small grain variety performance can vary greatly from one year to the next. This makes it nearly impossible to pick a single best variety. Consequently, producers should plant three or more varieties every season. Growing at least three varieties will reduce the risk of freeze injury, pest damage, and other forms of crop failure and maximize the potential for a high-yielding crop. Pick High Yielding Varieties Using the Wheat Variety Performance and Recommendations SmartGrains Newsletter, the “Above Average Yielding” varieties are good first choices. The next to consider are the “Above Average but Less Consistent Yielders.” These are varieties that on average had high yield but are more risky. Finally, the “Average Yielding Varieties” are likely to Variety Selection 9 produce acceptable yields but may not win a yield contest. Avoid Spring Freeze Damage Heading date is an important indication of how susceptible a variety will be to late-spring freeze damage. Early heading varieties are the most susceptible to freeze damage, while late heading varieties are the most likely to avoid yield loss due to spring freezes. Figure 3-1 shows how different varieties were damaged by the April 2007 freeze. Early heading varieties (shown in solid red) were severely damaged. Medium-early heading varieties (striped red) also tended to be more severely damaged. But late heading varieties (in black) were barely damaged at all. In 2008, spring freeze damage was observed at some locations and early and medium-early varieties were again the most damaged. Heading date also indicates when a wheat variety should ideally be planted. Medium and late heading wheat varieties tend to do best when planted at the start of the planting season, and consequently should be the first varieties a producer plants. Early and medium-early varieties tend to produce the highest yields when planted later in the fall. Barley is the earliest of the small grain species to head, so it is at greatest risk of suffering spring freeze damage and yield loss. In NC, the variety Boone had been a long-time standard for barley producers and rarely suffered late-spring freeze damage. Current varieties such as Thoroughbred and Dan have similar heading dates as compared to 10 Variety Selection AGS 2000 SS 520 Pioneer 26R31 AGS 2000/USG 3209 Featherstone 176 SS 8404 Renwood 3260 USG 3209 AGS 2060 Coker 9511 USG 3342 Coker 9553 SS 560 Chesapeake SS 8461 USG 3592 Coker 9312 Panola NC Neuse/USG 3592 Tribute/Roane SS 8308 USG 3910 SS MPV 57 Pioneer 26R12 Pioneer 26R24 Terral TV8558 USG 3665 Pioneer 26R15 SS 8302 SS 8309 NC Neuse Coker 9436 Coker 9184 Roane NC Neuse/Roane 0 10 20 30 40 50 60 70 Freeze Damage (%) 2007 Freeze Damage Early Heading Medium-Early Heading Medium Heading Late Heading Figure 3-1. Damage caused by the April 2007 freeze for different wheat varieties. Early heading varieties (shown in solid red) were severely damaged. Medium-early heading varieties (striped red) also tended to be more severely damaged. But, late heading varieties (shown in black) were barely damaged at all. Boone. So barley varieties that head earlier than Thoroughbred or Dan should be viewed as having a greater risk of yield reduction from freeze damage. Tailor Variety Selection to Match the Most Frequent Local Yield Robbing Factors Variety selection is the best defense against most pest problems encountered in NC. The three most common foliar fungal small grain diseases are powdery mildew, leaf rust, and Stagonosprora nodorum blotch (Photo 3-1). Wheat varieties that are resistant (or moderately resistant) to these diseases rarely require a fungicide application. Two soilborne viral diseases (soilborne wheat mosaic virus and wheat spindle streak virus) are common in some areas, and variety resistance is the only control method for these diseases (Photo 3-2). Fusarium sp. head blight or scab (Photo 3-2) can be problematic primarily in years with warm, moist weather at heading, and variety resistance is the best control method producers have. In recent years, numerous wheat fields have suffered losses due to Hessian fly (Photo 3-2). Wheat growers with a history of Hessian fly problems should select Hessian fly-resistant varieties. Here are some fine-tuning guidelines: • Central piedmont. The most common yield robbers in this area include spring freeze damage, barley yellow dwarf virus, and scab. Varieties that are high yielding, late heading (to avoid freeze damage), and resistant to these two diseases would be ideal for the NC piedmont. • Coastal plain. Powdery mildew, leaf rust, and soilborne mosaic virus are common wheat pests in the NC coastal plain. Ideal wheat varieties for this region should be high yielding and have resistance to all three of these diseases. • Tidewater. Hessian fly and soilborne mosaic virus have been frequent yield robbers in the NC tidewater. Ideal wheat varieties are high yielding and have resistance to soilborne diseases. Where Hessian fly has been a problem, varieties with resistance to it should also be selected. High Test Weight Varieties High test weight is usually associated with good quality. A low test weight will result in dockage at the elevator. Some varieties consistently have superior test weight. Even a high test weight variety, however, will produce a low test weight grain if drought, potassium or sulfur deficiencies, fungal diseases, lodging, or wet weather at harvest occur. Coastal plain producers with deep sandy soils who need high test weight grain should watch for potassium and sulfur deficiencies. Variety Selection 11 Photo 3-1. The three most common foliar fungal small grain diseases are powdery mildew (left), Stagonosprora nodorum blotch (center), and leaf rust (right). Wheat varieties that are resistant (or moderately resistant) to these diseases rarely require a fungicide application. Lodging Lodging is generally a greater problem in barley and oats than in wheat. Under intensive management practices, however, lodging will occur at a greater frequency in all small grains. A lodged crop can reduce test weight and slow combine operation. Milling and Baking Quality of Wheat Millers and bakers in NC use wheat for many diverse products, and certain varieties are superior to others for production of specific products. Therefore, if you plan to grow wheat for sale directly to a mill, discuss variety choice with the mill quality-control staff. Just like test weight, even a high-baking-quality variety can produce a low-quality grain if nitrogen, potassium or sulfur deficiencies, fungal diseases, lodging, or wet weather at harvest occur. Special Consideration for No-Till Variety Selection No-till producers should keep several additional facts in mind when choosing varieties. Tillering and fall growth are often slower in no-till small grains. Consequently, no-till producers often achieve higher yields if they plant during, or slightly ahead, of the opening planting dates (see chapter 5, “Small Grain Planting Dates” in this production guide: www.smallgrains.ncsu.edu/_Pubs/PG/Pdates.pdf). Planting early requires special care to select varieties that (1) are “late” heading to avoid freeze damage, (2) have “good” Hessian fly resistance to prevent fall infestations (especially important in the NC coastal plain and tidewater), (3) have at least moderate resistance to barley yellow dwarf virus (especially important in the NC piedmont), and (4) have at least moderate resistance to powdery mildew if planting in areas where powdery mildew is common. 12 Variety Selection Photo 3-2. Variety resistance is the best protection against Fusarium head scab (left). The only control method for soilborne mosaic virus (center) is variety resistance. Producers with a history of Hessian fly (right) should grow resistant varieties. 4. To Plant or Drill: Does Row Spacing Matter? Randy Weisz Many growers have wondered if they could plant wheat with the same implement they use to plant narrow-row corn or soybeans. Does it make a difference if wheat is drilled in 6- or 7.5-inch rows compared to being planted in 15-inch rows? If it does not make a difference, then the cost of replacing a drill could be avoided. We tested this idea in Salisbury in 2012, and Andrew Gardner tested it in Union Couny in 2010 and 2011. Our results were similar to those previously reported from other states. Figure 4-1 shows the results from winter wheat row-spacing tests conducted at 35 locations across six states (NC, VA, GA, PA, OH, and IN). As row spacing increases, wheat yield declines. The lowest yields were with 20-inch rows. Fifteen-inch rows had an average yield (BLUE line, Figure 4-1) of 60.8 bushels per acre, 7.5-inch rows averaged 68.7 bushels per acre, and 4-inch rows averaged 76.1 bushels per acre. The difference between 7.5-inch and 15-inch rows was 7.9 bushels per acre. If the price of wheat is $7.50 per bushel, that comes to $59.25 lost per acre by planting instead of drilling wheat. Does Row Spacing Matter? 13 50 60 70 80 90 2 4 6 8 10 12 14 16 18 20 Yield (bu/acre) Row Spacing (inches) All VA - 3 GA - 2 IN - 4 OH - 8 NC - 3 PA - 15 Winter Wheat Row Spacing Studies Test Locations Figure 4-1. Wheat yields at different row-spacings from studies conducted in NC, VA, GA, PA, OH, and IN. Some data from: Beuerlein, LaFever. Applied Agric. Res. 4:47-50, and 4:106-110; Gardner. www.smallgrains.ncsu.edu/_Pubs/OnFarm/ Union2010.pdf, and www.smallgrains.ncsu.edu/_Pubs/OnFarm/Union2011.pdf; Joseph, Alley, Brann, Gravelle. Agron. J. 77:211-214; Johnson, Hargrove, Moss. Agron. J. 80:164-166; Marshall, Ohm. Agron. J. 79:1027-1030, and Roth, Marshall, Hatley, Hill. Agron. J. 76:379-383. 5. Small Grain Planting Dates Randy Weisz and Ron Heiniger For producers of small grains, the goal is to select a planting date that gives an opportunity to develop as many fall tillers as possible while avoiding potentially severe damage associated with fall insect and disease infestations or an early spring freeze. Small grain tillers produced in the fall are most likely to have large heads with kernels of high-test weight: the two components of a high-yielding crop. Fall tillers also tend to have stronger root systems and consequently may be more stress resistant. The key advantage to planting early in the fall is the opportunity to make the most of warmer temperatures. The warmer the weather, the more tillers are likely to be produced. Cold temperatures impede growth, so it is important to plant small grains while there is still enough time and mild weather for tillers to form before winter sets in. On the other hand, planting too early can result in increased risk of diseases such as barley yellow dwarf virus and powdery mildew, increased risk of Hessian fly infestations, and increased risk of spring freeze damage. The same warm temperatures that enhance wheat growth also promote the development of insects and diseases and shorten the period from emergence to flowering. At least one night below 32oF is required to reduce Hessian fly or aphid populations and to slow disease development. Therefore, the selection of a planting date for small grains is a balance between achieving good fall growth and avoiding severe damage. Wheat The traditional guideline for finding the right compromise between planting early enough to encourage tillering, but late enough to avoid insect and disease problems, has been to plant wheat within one week of the first frost. Figure 5-1 shows starting dates for wheat planting in NC. The dates shown in this map are one week earlier than the 30- year average local freeze dates for weather stations throughout NC. These dates mark the start of the wheat planting season. In most parts of the NC tidewater, coastal plain, and southern piedmont, planting on these dates will allow wheat plants to develop two to three additional large tillers by February 1. That puts the crop in an excellent position for high yield potential and reduces the likelihood of needing to apply two applications of N fertilizer in the spring. It also assures that some cold weather will occur shortly after the seedlings emerge to reduce disease and insect pest activity. The dates shown in Figure 5-1, however, are often when soybean, cotton, and (in some parts of NC) peanut harvest is underway. This may force producers to plant later. Planting wheat later than the dates shown in Figure 5-1 can have a significant impact on a crop’s yield potential. For example, based on average NC weather records, planting 14 days later than the dates shown in Figure 5-1 usually results in enough warm weather to produce only one additional large tiller per plant by February 1 in the NC tidewater and central to southern coastal plain. In the rest of the state, not enough warm weather may occur to get even a single additional large tiller to develop by February 1. This makes it very important to ensure that a late planted crop was drilled in at higher seeding rates (see chapter 7, “Small Grain Seeding Rates” in this production guide: www.smallgrains.ncsu.edu/_Pubs/PG/Srates.pdf) and to scout the wheat in late January to determine if an early N fertilizer application will be required in February to stimulate further tiller development in the spring (see chapter 8, “Nitrogen Management for Small Grains” in this production guide: www.sm a l l g r a ins. n c s u . e du/_Pubs /PG/ Nitrogen.pdf). Barley, Oats, Rye, and Triticale Barley and oats should be planted about 5 to 10 days earlier than the dates shown for wheat in 14 Planting Dates Figure 5-1. Rye planting dates are similar to those for wheat. Triticale varieties that have been developed for NC, like Arcia, can be planted on the same dates as wheat. Trical triticale varieties that have been tested in NC and shown to head at the same time as wheat can also be planted on the same dates shown in Figure 5-1. However, some triticale varieties (such as Trical 498) are early heading, and need to be planted late to avoid spring freeze damage. It is important to know the maturity rating for the triticale variety before selecting a planting date. Special Considerations for No-Till Heavy residue left on the soil surface can reduce soil temperatures. This results in slower germination and tiller growth. Because fall growth can be reduced in no-till, planting small grains early becomes even more important. Establishing a healthy, uniform stand by planting close to the dates shown in Figure 5-1 may be a key to achieving high yields in no-till. Some successful no-till producers say they need to plant on or even a little earlier than these dates (see chapter 6 “Beating Soybean Harvest: A Very-Early-Wheat-Planting System” in this production guide: www.smallgrains.ncsu.edu/_Pubs/PG/ VeryEarly.pdf). Special Considerations for Hessian Fly Hessian fly has become a serious wheat pest in NC. Because Hessian fly adults are killed by freezing temperatures, a traditional method for preventing Hessian fly infestation is to delay planting until after the first freeze (often called the fly-free date). The fly-free date concept has not worked well in NC (see chapter 11, “Insect Pest Management,” in this guide: www.smallgrains.ncsu.edu/_Pubs/PG/Insects.pdf). Often a “killing freeze” does not occur until December in many areas of NC, after most growers need to have wheat planted if they want to have enough fall growth to produce high yields. Delayed planting will only prevent Hessian fly infestations if a freeze has occurred. Planting Dates 15 Murphy Asheville Jefferson Mt Airy Mocksville Salisbury N. Wilkesboro Hickory Forest City Gastonia Concord Albemarle Monroe Jackson Springs Reidsville Oxford Arcola Siler City Raleigh Sanford Smithfield Fayetteville Laurinburg Whiteville Willmington Longwood Warsaw GoldsboroKinston Rocky Mt Murfreesboro Elizabeth City Plymouth New Holland Bayboro Morehead City Hofmann Forest Lumberton Sept 25 - 30 Sept 30 - Oct 5 Oct 5 - 10 Oct 10 - 15 Oct 15 - 20 Oct 15 - 20 Oct 20 - 25 Oct 15 - 20 Oct 25 - 30 Oct 25 - 30 Oct 20 - 25 Oct 25 - 30 Oct 30 - Nov 4 Oct 30 - Nov 4 Oct 30 - Nov 4 Figure 5-1. The start of wheat planting dates. The dates shown on this map are 7 days earlier than the date when there is a 50% chance of having a freeze. 6. Beating Soybean Harvest: A Very Early Wheat-Planting System Randy Weisz Why Plant Before Soybean Harvest In NC, the ideal dates for planting wheat (see Figure 5-1: www.smallgrains.ncsu.edu/_Pubs/PG/ Pdates.pdf) herald the beginning of soybean and cotton harvest. Consequently, wheat planting is often delayed until cold wet weather has set in, and wheat development suffers. Research in Virginia and NC has shown that up to 85 percent of the yield in a any given wheat field is made up by grain heads formed on tillers that developed in the warm fall weather. When planting is delayed, there is less time for fall tillers to develop and this results in reduced yield potential. This is especially true for no-till. Wheat planted no-till (especially in NC coastal plain and tidewater soils) tends to grow and tiller more slowly than when planted in conventionally tilled seedbeds. Planting early is one way to help no-till seedlings make up for this slower growth and produce more fall tillers. It would be ideal if wheat could be planted before the start of soybean or cotton harvest to take full advantage of the warm tiller-inducing fall weather. Challenges and Solutions I n c h a p t e r 5 , “ S m a l l Gr a i n P l a n t i n g Dates” (www.smallgrains.ncsu.edu/_Pubs/PG/ Pdates.pdf), we stated that the ideal time to plant wheat was within 7 to 10 days of the first freeze. Planting earlier than that puts the crop at risk of early season insect damage, including wireworm (especially in no-till production in the NC coastal plain), Hessian fly, and aphid feeding that can spread barley yellow dwarf virus. One way to avoid these problems is to use an insecticidal seed treatment (such as GauchoXT or Cruiser/ Dividend). These seed treatments can give about 19 days of protection from these insects. A second potential problem is too much fall tiller production resulting in very thick stands that may lodge before the end of winter. A good way to avoid this is to reduce seeding rates. Finally, many growers will say that they cannot plant too early because of the risk of spring freeze damage. The earlier wheat is planted, the earlier it heads out in the spring. Once wheat has headed, it becomes freeze tender and can lose yield if a freeze occurs. In NC most “early-heading” wheat varieties head in the first week of April. “Late-heading” varieties may head out one to two weeks later. Consequently, if there is a freeze the end of the first week in April, early-heading varieties may be damaged while the late varieties may escape. Making It Work There are five essential parts to the very early wheat-planting system. Planting 10 Days to Two Weeks Early Plant 10 days to two weeks earlier than the dates shown in Figure 5-1: www.smallgrains.ncsu.edu/ _Pubs/PG/Pdates.pdf. Because the seed treatments used in this system only give limited protection, planting should not be more than about 14 days early. In the NC central piedmont (at Salisbury), we have been planting between September 29 and October 3. In the NC central coastal plain (at Kinston), we have been planting from October 6 through October 8. In the NC tidewater at Plymouth and Terra Ceia, we’ve planted between October 8 and 11. Plant Only Late-Heading Varieties Late-heading varieties have the lowest risk of damage from a spring freeze. These are the only 16 Very Early Planting varieties that should be used in the very early planting system. This system has been tested with NC-Neuse and Roane (two late-heading wheat varieties) for six years in Salisbury, and shown to work well. Always Use an Insecticidal Seed Treatment Treating all seed with an insecticidal seed treatment such as GauchoXT or Cruiser/Dividend is critically important. In our very early planting trials in the NC piedmont, using an insecticidal seed treatment usually resulted in a 10-bushel-per-acre yield advantage over untreated seed. In eastern NC, the seed treatment is critical to prevent Hessian fly, wireworm, and aphid infestations. Plant at Reduced Seeding Rates Early planting results in extra tiller development. To avoid excessive growth, wheat is planted with one-third less seed then normal (see chapter 7, “Small Grain Seeding Rates For NC” in this production guide: www.smallgrains.ncsu.edu/_Pubs/PG/Srates.pdf). Restrict No-Tillage to the Piedmont In the NC piedmont this system has worked well with no-till planting. In the NC coastal plain and tidewater, very early no-till planting is not recommended. This is due to the slower growth that young wheat plants exhibit when planted no-till in eastern NC. This slower growth combined with possible wireworm and Hessian fly damage can reduce no-till yields even with the insecticidal seed treatments. On the other hand, very early planting in eastern NC has worked well with conventional tillage. Very-Early-Planted Variety Testing Tests across NC have shown that when the five steps outlined above are followed, wheat yields are similar to those achieved when planting at the normal recommended times shown in Figure 5-1: (www.smallgrains.ncsu.edu/_Pubs/PG/Pdates.pdf) using normal seeding rates (Tabl e 7-1: www.smallgrains.ncsu.edu/_Pubs/PG/Srates.pdf) and untreated seed. The very early planting even at the lower seeding rates allows the wheat time to tiller and often to produce a thicker stand than would normally be achieved (Photo 6-1). Yield results from trials conducted in Salisbury in 2009, 2010, 2011, and 2012 are shown in Table 6-1. Very Early Planting 17 Photo 6-1. Even though the very-early-planting-system uses 30% less seed, it often results in denser stands due to greater tillering in the fall. Left: The very-early-planting system at Plymouth, NC, planted on October 8, 2009. Right: Normal wheat planting system also at Plymouth, planted on October 29, 2009. The photographs were taken on February 17, 2010. Table 6-1. Very-early-planting variety test results from Salisbury, NC. The tests were planted on Sept. 29 using reduced seeding rates, GauchoXT, and only late-heading varieties. Late-Heading Wheat Varieties Yield (bu/acre) 2012 2011 2010 2009 Pioneer 26R20 109.0 DynaGro 9053 105.9 Pioneer 26R12 101.3 131.5 99.7 106.1 DynaGro Shirley 101.2 133.2 102.8 Branson 98.1 131.3 Pioneer 25R32 93.6 127.2 UniSouth Genetics 3665 91.2 133.5 92.2 102.4 AgriPro Coker 9436 91.1 130.3 86.9 85.5 VA Merl 90.6 133.2 92.9 Pioneer 26R15 90.6 82.4 99.0 Southern States 8302 90.4 132.6 97.1 102.6 ARS Appalachian White 66.6 DynaGro V9713 128.2 90.0 99.5 NC Yadkin 122.6 NC Neuse 118.4 87.5 86.4 UniSouth Genetics 3725 91.1 VA Roane 85.8 93.5 18 Very Early Planting 7. Small Grain Seeding Rates for North Carolina Randy Weisz and Ron Heiniger Wheat, Triticale, and Hulled Barley The results from ten wheat seeding-rate studies (conducted in Virginia and North Carolina) are shown in Figure 7-1. In these studies certified seed with a high germination rate was planted on different sites at seeding rates ranging from about 0.6 million to over 2.0 million seeds per acre. All ten tests were planted using conventional tillage near the recommended dates shown in Figure 7-2 for North Carolina. In Figure 7-1 yield is shown relative to the highest yielding seeding rate in each test. So, for each of the ten tests, the yield at the highest seeding rate is set to 0. As seeding rates range from 0.9 to 1.6 million seeds per acre, average yield (blue line in Figure 7-1) only varies by about 1 bushel per acre! The grey box in Figure 7-1 shows a broad range in seeding rates (1.1 to 1.5 million seeds per acre) that produced the highest average yields. As seeding rates drop below that, yield becomes highly variable. In some years when the fall weather was warm, these lower seeding rates yielded well. In other years when the weather did not favor rapid tillering, low seeding rates resulted in up to a 12 bushel loss. Seeding rates above 1.5 million seeds per acre generally resulted in lower yields probably due to higher disease levels and lodging. Seeding Rates 19 Figure 7-1. Ten wheat seeding-rate studies conducted using certified seed with high germination (at least 90 percent), planted into conventionally tilled seed beds and planted near the dates shown in Figure 7-2. Yield is shown as a percent of that at the highest seeding rate. Seeding rates ranged from 0.6 to 2.3 million seeds per acre. The grey box represents suggested seeding rates based on these tests. J J J J J J J J J J J J J J J J J J J J J J J J J J J J J J J J J J -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 Yield (bushels per acre from optimum) Seeding Rate (million seeds per acre) Timely Planted Yield The grey area in Figure 7-1 shows an optimal range in seeding rates from 1.1 to 1.5 million seeds per acre. This range in seeding rates is similar to what other researchers have found. For example, Syngenta Seed has been doing wheat seeding-rate studies in the NC coastal plain. They report that optimum yields are frequently reached for most growers at around 1.1 million seeds per acre. They recommend 1.5 million seeds per acre for growers interested in intensive management. The intensive wheat management guide from the Virginia Polytechnic Institute recommends planting 1.31 to 1.52 million seeds per acre. Many growers think about small grain seeding rates in terms of pounds of seed per acre. Table 7-1 shows how 1.31 and 1.52 million seeds per acre can be converted into more familiar units. The lower rate of 1.31 million seeds per acre is equal to 30 seeds per square foot. The higher rate (1.52 million seeds per acre) is the same as 35 seeds per square foot. But, the number of pounds of seed needed to reach these targets depends on seed size. A large seeded variety may only have 10,000 seeds per pound compared to a small seeded variety that could have up to 15,000 seeds in a pound. This makes planting a single number of pounds of seed per acre problematic. Table 7-1 shows that the ideal seeding rate of 1.31 to 1.52 million seeds per acre can range all the way from 87 to 152 pounds of seed per acre depending on seed size! It is important that growers consider seed size when selecting seeding rates based on pounds per acre! Most drills have tables that indicate how to set the seed metering mechanism for a given seeding rate in pounds per acre. Ideally, if the seed size is known (for certified seed it is often printed on the tag attached to the bag), a grower could use Table 7-1 to determine the pounds of seed to plant per acre, and use the drill manufacturer’s information to find the proper drill setting to plant that number of pounds per acre. However, experience has shown that using these factory settings can result in large over- or under-seeding. For example, in 2001 we calibrated a John Deere no-till drill to plant the correct seeding rate (based on Table 7-1) for 15 wheat varieties, each of which had half the seeds treated with GauchoXT seed treatment and half untreated. To produce the same seeding rate for each variety, we had to change the drill setting from 27 all the way to 45—depending on the variety and 20 Seeding Rates Murphy Asheville Jefferson Mt Airy Mocksville Salisbury N. Wilkesboro Hickory Forest City Gastonia Concord Albemarle Monroe Jackson Springs Reidsville Oxford Arcola Siler City Raleigh Sanford Smithfield Fayetteville Laurinburg Whiteville Willmington Longwood Warsaw GoldsboroKinston Rocky Mt Murfreesboro Elizabeth City Plymouth New Holland Bayboro Morehead City Hofmann Forest Lumberton Sept 25 - 30 Sept 30 - Oct 5 Oct 5 - 10 Oct 10 - 15 Oct 15 - 20 Oct 15 - 20 Oct 20 - 25 Oct 15 - 20 Oct 25 - 30 Oct 25 - 30 Oct 20 - 25 Oct 25 - 30 Oct 30 - Nov 4 Oct 30 - Nov 4 Oct 30 - Nov 4 Figure 7-2. The start of wheat and triticale planting dates for NC. Timely planting for oats and barley is five to ten days earlier. seed treatment! Our experiment revealed that the drill settings required to achieve the correct wheat-plant population varied widely among varieties and seed treatments and this variation was not reflected in the manufacturer’s charts. The best way to ensure a correct small grain seeding rate is to calibrate the drill for the specific seed being planted. The most accurate way to calibrate is to base seeding rates on the desired number of seed per drill-row foot. This number does not vary across seed sizes or change depending upon seed treatments. Table 7-1 gives target seeding rates in terms of seeds per drill-row foot across a range of drill-row widths. For example, Table 7-1 shows that if a grower has a drill with 7.5-inch row spacing, the correct seeding rate is between 19 and 22 seeds per drill-row foot (assuming planting is on time, the seed has at least 90 percent germination, and planting is into a conventionally tilled seed bed). Hulless Barley Hulless barley seed is more easily damaged then hulled seed. Consequently, hulless barley must be planted at higher seeding rates than traditional hulled varieties. Dr. Wade Thomason, the corn and small grain specialist at Virginia Tech, gives this guideline: When using high-quality hulless barley seed with at least 90 percent germination, the target seeding rate is 2.2 million seeds per acre or 50 seeds per square foot when using a conventionally tilled seedbed. Table 7-2 gives hulless barley seeding rates across a range of seed sizes and drill row widths. Seeding Rates 21 Table 7-1. Wheat, triticale, and hulled barley seeding rates for conventionally tilled seed beds planted on time using a target of 1.31 to 1.52 million seeds per acre with 90 percent germination as a standard. These rates need to be increased by 20 percent for no-till. Million seeds per acre: 1.31 1.52 Seeds per square foot: 30 35 Seed size (seeds per pound) Pounds of seed per acre 10,000 131 152 11,000 119 138 12,000 109 127 12,500 105 122 13,000 101 117 14,000 94 109 15,000 87 101 Drill row spacing (inches) Seed per drill-row foot 6 15 17 7 18 20 7.5 19 22 8 20 23 Table 7-2. Hulless barley seeding rates for conventionally tilled seed beds using a target of 2.2 million seeds per acre or 50 seeds per square foot with 90 percent germination as a standard assuming planting is on time. These rates need to be increased by 20 percent for no-till. Million seeds per acre: 2.2 Seeds per square foot: 50 Seed size (seeds per pound) Pounds of seed per acre 10,000 218 11,000 198 12,000 182 12,500 174 13,000 168 14,000 156 15,000 145 Drill row spacing (inches) Seed per drill-row foot 6 25 7 29 7.5 31 8 33 Oats and Rye Oats should be planted at 2 bushels per acre. Rye should be planted at 1 to 1.5 bushels per acre. Low Germ Seed The seeding rates shown in Tables 7-1 and 7-2 are for seed with at least 90 percent germination. Some certified seed, and most bin-run seed, will not have germination rates this high. Consequently, the seeding rates in these tables need to be increased for seeds with a germination rate lower than 90 percent. Table 7-3 shows the increase required for different levels of germination. Low Germ Seed Example If a grower wants to plant wheat at the higher seeding rate of 1.52 million seeds per acre and has a variety with 12,500 seeds per pound, Table 7-1 indicates the recommended seeding rate would be 122 pounds of high germ seed per acre. A germ test indicates the seed has a germination rate of only 80 percent. Table 7-3 shows the seeding rate will have to be increased by 13 percent to compensate. Thirteen percent of 122 pounds is 16 pounds. So the grower would plant 122 + 16 = 138 pounds of this seed with lower germ. What About Planting Late? In NC, small grains frequently follow soybeans that are harvested in October or November. This results in small grains being planted after the optimal planting dates. When wheat, triticale, hulled or hulless barley is planted after the dates shown in Figure 7-2, seeding rates should be increased by 4 to 5 percent for each week planting is delayed. Planting Depth Wheat varieties have semidwarf genes that reduce overall plant height. These also reduce the chances of seedling emergence if the seeds are placed too deep. Conversely, a shallow planting can result in uneven germination due to dry soil. Small grain seeds should be planted 1 to 1.5 inches deep when soil moisture levels are adequate and slightly deeper if moisture is deficient. Seeding Rates for No-Till No-till planting causes special challenges related to uneven seed beds and surface residue. Although seeds should still be planted 1 to 1.5 inches below the soil surface, be aware that changes in the depth of any residue and undulations in the soil’s surface may result in the drill missing the targeted seeding depth. When residue from the previous crop is unevenly distributed, achieving a uniform and correct planting depth can be difficult. Where the residue is uneven, the planting depth may be too shallow under high residue and too deep in areas of light residue. This can result in thin stands and excessive risk of winterkill. Preparation for no-till small grains begins with evenly distributing crop residues while harvesting the previous crop. To obtain a uniform stand, start with a seeding rate that is 20 percent higher than what is recommended for conventional tillage (Tables 7-1 and 7-2). When no-till drilling, stop periodically and make sure that the planting depth is uniform and correct. 22 Seeding Rates Table 7-3. Increase in seeding rates required for lower germination seed. Seed germination Increase seeding rates in Tables 7-1 and 7-2 by: 85% 6% 80% 13% 75% 20% 70% 29% 65% 38% Drill Calibration The manufacturer’s seeding rate chart that comes with commercial drills is a rough estimate of how many pounds of seed will be planted at a given setting. Experience with wheat seed has shown that this estimate can be off by as much as 100%. The best way to be sure the correct seeding rate is being planted is to calibrate the drill for each seed lot being grown. Three methods for calibrating a drill are d e m o n s t r a t e d i n a n o n l i n e v i d e o at www.smallgrains.ncsu.edu/drill-calibration.html. The simplest drill calibration method is outlined below: 1. Select the desired seeding rate. For example, if planting on-time, using conventional tillage, and high quality seed, a recommended wheat seeding rate would be 1.3 million seeds per acre. 2. Use Table 7-1 to convert seeds per acre to seeds per drill row foot. For example, if planting at 1.3 million seeds per acre with a drill that has 7.5- inch row spacing, Table 7-1 indicates that converts to 19 seeds per foot of row. 3. Hook a tractor to the drill, put at least several inches of seed in the hopper, and use the setting that is a “best guess” at what is needed to get the correct seeding rate. 4. Run the drill for 20 to 30 feet over firm ground (like a dirt road) with minimum down pressure on the openers and closing wheels so that the seed is exposed and easy to see. 5. Pick a drill row and count the number of seed in two feet. 6. If there are too many seed, lower the setting and try again. If there are too few seed, increase the setting and repeat. For example, if the target is 19 seed per drill row foot, but the drill dropped 24, the setting needs to be reduced. 7. Repeat step 6 until the number of seed being dropped is correct. Record the setting needed for this seed lot. Special Considerations for Broadcast Seeding Broadcast seeding often results in uneven seed placement in the soil, which results in uneven emergence and stands. Seeds may be placed as deep as 3 to 4 inches, where many seeds will germinate but will not emerge through the soil surface. Other seeds may be placed very shallow or on the soil surface. These seeds often do not survive due to dry soil or winter damage. The uneven stands from broadcasting often result in lower yields compared with drilling. One method of improving stand uniformity is to broadcast seed in two passes across the field using half the seeding rate for each pass. The second pass is made perpendicular to the first pass. Although this method should improve stand uniformity, it also increases the time required to seed the field. Because plant establishment potential is reduced and seed placement is not uniform, seeding rates should be increased for broadcast seeding. Increase broadcast seeding rates by 30 percent to 35 percent over drilled seeding rates. Seeding Rates 23 Online VIDEO: How to Calibrate a Drill www.smallgrains.ncsu.edu/drill-calibration.html Broadcasting wheat with fertilizer is a fast way to seed small grains. Take precautions to ensure that the seed is uniformly blended with the fertilizer and that the fertilizer-seed mixture is uniformly applied. Seed should be mixed with fertilizer as close to the time of application as possible and applied immediately after blending. Allowing the fertilizer-seed mixture to sit after blending (longer than 8 hours), particularly with triple super phosphate (0-46-0) or diammonium phosphate (18-46-0), results in seed damage (reduced germination) and, subsequently, a poor stand. Considerations for Overseeding Small grains may be planted by overseeding in standing, unharvested crops. To follow soybeans, seed as the first soybean leaves begin to drop. Following cotton, seed just before defoliation. The small grain can be injured or killed if it is growing when a desiccant is used. If no desiccant is used, seed when the leaves begin to drop. The leaves will form a mulch that conserves moisture and enhances germination. The success or failure of overseeding depends on available moisture. Overseeding before a rainfall event improves the chances of success. Wheat and rye tend to emerge better when overseeded than do oats or barley. Test the Results: Check the Stands No matter how you plant the seed, be sure to check the stands shortly after emergence. Is the stand uniform? Determine the number of healthy seedlings present in a square foot. There should be 22 to 25 seedlings (or more, if planted late). If the stand is uniform and the plant density is correct, then the planting was successful. References Some materials in this chapter were adapted from: Alley, Brann, Stromberg, Hagood, Herbert, Jones. 1993. Intensive Soft Red Winter Wheat: A Management Guide (Publication 424-803). Virginia Polytechnic Institute, Cooperative Extension Service. Ambrose. 1998. Wheat On-Farm-Test Report. Beaufort County Cooperative Extension Service & NC State University. (www.smallgrains.ncsu.edu/_Pubs/OnFarm/BFT1998.pdf). Ambrose. 1999, 2000, & 2001. Wheat On-Farm-Test Report. Beaufort County Cooperative Extension Service & NC State University. Joseph, Alley, Brann, Gravelle. 1985. Row Spacing and Seeding Rate Effect on Yield and Yield Components of Soft Red Winter Wheat. Agron. J. 77:211-214. Lee, Herbek. 2009. A Comprehensive Guide to Wheat Management in Kentucky (Publication ID-125). Lexington, KY: University of Kentucky College of Agriculture, Cooperative Extension Service. Smith, Wood, Grandy, Williams, Smith, Powell. 2006. NE Expo Wheat Field Day Test Results. Perquimans, Pasquotank, Currituck, Chowan, Gates, and Camden County Cooperative Extension Service & NC State University. (www.smallgrains.ncsu.edu/ _Pubs/OnFarm/NEX2006.pdf) Weisz, Love, Tarleton. 2011. Southern Coastal Plains Small Grains Extension Program 2011 Test Report. NC State University. (www.smallgrains.ncsu.edu/_Pubs/OnFarm/SCNC2011.pdf) Weisz, Love, Tarleton. 2012. Southern Coastal Plains Small Grains Extension Program 2012 Test Report. NC State University. (www.smallgrains.ncsu.edu/_Pubs/OnFarm/SCNC2012.pdf) 24 Seeding Rates 8. Nitrogen Management for Small Grains Randy Weisz and Ron Heiniger Nitrogen management is one of the most important keys to successful small grain production. It is also one of the easiest management strategies to misuse, resulting in yield reductions and environmental damage. To achieve optimum yields, follow the correct N guidelines for applications in the fall, winter, late January to early February, and at growth stage 30 (which usually occurs in March). Chapter 9, “Nutrient Management for Small Grains” (www.smallgrains.ncsu.edu/_Pubs/PG/Nutrient.pdf), discusses soil testing and management of all other nutrients. We discuss N management first and separately because there is no soil test useful for making N recommendations in NC, and because of its importance for small grain production. Fall: Preplant Nitrogen When Planting Near the Recommended Dates When planting on time, 15 to 30 pounds preplant N per acre are generally sufficient to promote maximum growth and tillering. This application can be very important for high yields because N stress early in the season will prevent adequate tillering. When small grains follow soybeans or peanuts, enough carryover N may be present to meet small grain fall requirements. Unfortunately, the availability of carryover N is difficult to predict and there is no method for testing for available N in the fall. In many years and locations, the N released from a previous legume crop many not be available until the following spring or even summer, which is too late to support fall tillering. Consequently, unless experience with specific fields indicates otherwise, a small amount of preplant N is recommended even when following soybeans or peanuts. When Planting Later Than Recommended Research has shown that late-planted small grains may not respond to preplant N applications. When temperatures are too low to promote tillering, preplant N cannot be taken up by the plants and is easily leached out of the soil. Adding preplant N even at high rates cannot simulate tillering in cold soils. Consequently, when planting late, application of preplant N to small grains might be skipped. Early Planting System In chapter 6, “Beating Soybean Harvest: A Very Early W he a t - P l a n t i n g S y s t em” ( o n l i n e a t : www.sm a l l g r a ins. n c s u . e du/_Pubs /PG/ VeryEarly.pdf), we introduced a system for very early wheat planting. Small grains planted before the optimal planting dates risk freeze damage. So when planting very early, it is important to follow all the recommendations given in that chapter. Additionally, preplant N application to early planted small grains promotes increased tillering, but this can also increase the risk of freeze damage. While applying N to early planted small grains will often result in better looking stands, research has shown that it generally does not increase yields. Consequently, preplant N should be reduced or eliminated when planting earlier than the recommended dates (see chapter 5, "Small Grain Planting Dates, in this production guide: www.smallgrains.ncsu.edu/_Pubs/PG/Pdates.pdf). No-Till Preplant N management for no-till small grains is similar to conventional-till with a couple of minor differences. Many no-till growers find that their pre-plant N rates need to be on the high end of the recommended range. Therefore, when planting during the recommended planting dates, consider as much as 30 lbs of preplant N per acre. Growers using the early planting system may also want to Nitrogen Management 25 consider applying 15 to 30 lb N per acre preplant, particularly in conditions where corn or sorghum residue is heavy. Winter: Rescue Applications Nitrogen management during the winter consists of making sure the crop does not become N deficient. Small grains under N stress in the winter can lose tillers, which may reduce yield. Indications of a possible N deficiency are a pale green color, thin and poorly developing stands, and leaching rains after planting. An application of 15 to 30 pounds N per acre can help to green the crop back up if these symptoms occur. This rescue application needs to be made when daytime temperatures are expected to be above 50oF. Late January and Early February: Last Chance to Grow More Tillers Late January to early February is the time to determine if the crop has enough tillers to optimize yield. This is a very important decision. Apply N in January or February only if tiller densities are less than 50 tillers per square foot. If N is not needed, applying N in January or February results in increased risk of freeze damage, disease, lodging, and reduced yield. If tillering is low, however, an early application of N can help to stimulate further tiller development in the last few weeks before growth stage 30, resulting in higher yield and profit. The following guidelines will help you decide whether to apply N in late January or early February. Guidelines for Wheat If at the end of January or in the first week of February, wheat looks as thick as that shown in Photo 8-1, it is well on the way to being a potentially high yielding field. This wheat has about 100 well-developed tillers per square foot and should not have any N applied until growth stage 30. A well-developed tiller is one with at least three leaves. The wheat in Photo 8-2 is a “medium” density stand with about 50 tillers per square foot. It also is well on the way to being a good yielding crop, and should not have any N applied until growth stage 30. The wheat in Photo 8-3, however, is poorly tillered and only has about 20 tillers per square foot. It has a low yield potential and needs more tillers to develop in February. It should have 50 to 70 pounds N fertilizer applied in late January or early February. A second N application should be made to finish this crop off at growth stage 30. Thin stands like those shown in Photo 8-3 need timely weed management, but should not have 2,4-D applied because 2,4-D may inhibit tiller development. Growers also need to scout for cereal leaf beetle in April, as these insect pests are often attracted to thin wheat stands. Wheat stands that are thicker than the stand shown in Photo 8-3 but not as well developed as that shown in Photo 8-2 also need an early N application. Such a field will yield best with 40 to 50 pounds of N fertilizer applied in late January or early February and a second N application to finish the crop off at growth stage 30. This approach to stand evaluation is shown in Figure 8-1. In late January and early February, a “tiller” is considered to be any stem that has three or more leaves. Rough estimates of tiller density can 26 Nitrogen Management Online VIDEO: Counting Tillers to Optimize N Rates www.smallgrains.ncsu.edu/tiller-counting.html be made by comparing a wheat field with Photos 8-1 through 8-3, or more exactly by counting tillers. To determine tiller density, count well-developed tillers (those with at least three leaves). Ignore small tillers that have only one or two leaves. Do not be concerned with differences between the main plant and younger side tillers. Just count any stem with at least three leaves as a tiller. The final count will include main plants, tillers, and side tillers. Count all the tillers that have at least three leaves in a yard of row. Do this in several places and take an average. Tiller density is then computed as follows: Tillers per square foot = (tillers per yard of row) × 4 (row width in inches) Example: If in five counts of tillers in a yard of row the average was found to be 102 tillers per row and the row spacing is 7.5 inches, then tiller density is: 102 × 4 ÷ 7.5 = 54.4 tillers per square foot. An alternative is to mark out a square foot of ground and count all the tillers in that area that have at least three leaves. Do this in several places and calculate the average. Guidelines for Oats, Barley, Triticale, and Rye Research on counting tillers to time N applications for these crops has not been done. Growers will need to rely on past experience to judge when splitting N will benefit oat, barley, or triticale stands that are thin in late January to early February. Growth Stage 30: The Most Important Time to Apply Nitrogen! During growth stage 30, small grains switch from producing tillers, to starting reproductive growth. In the first phase of reproductive growth, the stem elongates, the plant gets taller, and the small grain crop begins to take up large amounts of N. The Nitrogen Management 27 Photo 8-1. Well-tillered – about 100 tillers per square foot. Photo 8-2. Medium-tillered – about 50 tillers per square foot. Photo 8-3. Poorly-tillered – about 20 tillers per square foot. Apply 50 - 70 lb N as soon as possible Does the wheat have at least 50 tillers per square foot ? (see Photo 8-2) YES NO NO YES Is the wheat very thin with only 20 to 30 tillers per square foot ? (see Photo 8-3) Do not apply N until growth stage 30 Apply 40 - 50 lb N as soon as possible Figure 8-1. Late January to early February guidelines for wheat N fertilization. future grain head is formed at this stage (although still underground), and N stress at this growth stage will affect head formation and result in smaller heads. Since N at this stage of development is critical and larger amounts of N are needed to satisfy N requirements, the bulk of spring N fertilizer needs to be applied at this stage. A typical fertilizer application rate at growth stage 30 for wheat is 80 to 120 pounds N per acre (minus any that was applied in late January or early February to stimulate tillering). However, optimal N rates can vary dramatically from field to field and year to year depending on the weather, the crop’s yield potential, and the presence of carry-over N from previous crops. Tissue testing at growth stage 30 is one way to help fine-tune N rates to maximize economic return. The Wheat Tissue Test Tissue testing for wheat N rate recommendations was developed in VA and has been available for many years. It uses the N concentration detected in a tissue sample collected at growth stage 30. Research in NC, however, has shown that the VA recommendations can overestimate the required N for our growing conditions. Therefore, a new system has been developed that is helpful in optimizing wheat N fertilizer rates specifically for NC producers. This research indicates that N rates based on a tissue test are most reliable for wheat grown on well-drained soils. The test should not be used on poorly-drained organic soils. This new system and subsequent recommendations are especially helpful when N prices are high and growers need to minimize input costs without compromising yield. For assistance with growth stage 30 tissue testing, NC producers can contact an NC Department of Agriculture & Consumer Ser vices (NCDA&CS) r egional agr onomi st (www.ncagr.gov/agronomi/rahome.htm) or county Extension agent (www.ces.ncsu.edu). Here are the steps and information needed to determine the optimum N rate with a tissue test. Step 1: Determine the Growth Stage As temperatures warm in spring, tillering stops and the wheat crop’s demand for N increases rapidly. This is the beginning of stem elongation, often referred to as growth stage 30. Because growth stage 30 is the best time to apply N fertilizer to winter wheat, it is important to know when the crop reaches this stage. The calendar date when wheat reaches growth stage 30 is influenced by variety, planting date, and environmental conditions. Early-heading varieties can reach it in February. Late-heading varieties may not reach growth stage 30 until mid-March. One clue that the wheat is at growth stage 30 is that the plants start to stand up and get taller. However, the best way to tell if wheat is at growth stage 30 is to pull up several plants and split the stems down their centers all the way to the base where the roots grow. Prior to growth stage 30, the growing point will be at the very bottom of the stem just above the first roots. At growth stage 30, the growing point will have moved ½-inch up the stem (Figure 8-2). After growth stage 30, it will move further up the stem and be above the soil surface. Tissue samples can be taken when the 28 Nitrogen Management Growing Point First Roots Figure 8-2. Wheat stem cross-section at growth stage 30. The growing point will be dark green, about 1/8-inch long, look like a tiny pine cone, and prior to growth stage 30 be at the very base of the stem next to the first roots. At growth stage 30 it will have moved 1/2-inch up the stem. growing point is between ¼- and ¾-inch above the base of the stem. Step 2: Collect Tissue and Biomass Samples Two pieces of information are needed to determine the optimum N rate: percentage of tissue N and biomass. At growth stage 30, take a tissue sample by cutting wheat plants from 20 to 30 representative areas in the field. The plants should be cut ½-inch above the ground. Soil and dead leaf tissue must be removed and the cuttings placed in a paper bag labeled “tissue.” The percentage of N is detected in this tissue sample. For the most accurate N rate recommendation, an estimate of above-ground biomass is also required. At one representative location in the field, cut all the wheat along a 36- inch section of row, remove any soil and weed tissue, and place the entire sample in a second paper bag labeled “biomass.” The biomass or weight is detected in this sample. The two samples should be shipped to the NCDA&CS Agronomic Division immediately. If samples have to be stored for more than 24 hours after collection, they must be dried to prevent spoilage and loss of biomass. Step 3: Use the Chart and Table with the Plant Report An example of the NCDA&CS plant report is shown in Figure 8-3. In this example, the dry weight of the biomass cut from the 36-inch length of row was 36 grams and the tissue N percentage was 3.5. Using the biomass dry weight and the N percentage values, N fer tilizer recommendations are determined using either the BLUE, RED or GREEN line in Figure 8-4. Low biomass wheat fields use the BLUE line. Medium biomass fields use the RED line. High biomass fields use the GREEN line. To determine which line to use, consult Table 8-1. Find the biomass value on the left side of Table 8-1. Look across the table to find the drill row spacing used in the field. The intersection of the correct drill-row column and the dry-weight row indicates which colored line to use. If the drill row spacing in the SHOP field (Figure 8-3) is 6 inches, then Table 8-1 indicates the GREEN line should be used to get a N fertilizer rate recommendation. If the wheat was broadcast seeded, there will be no drill rows to sample and Table 8-1 cannot be used. In broadcast fields, the biomass dry weight in a square yard will need to be estimated. Low biomass fields are defined as those with less than 84 grams of dry biomass per square yard. Medium biomass Nitrogen Management 29 Figure 8-3: NCDA&CS Plant Analysis Report. Table 8-1. Line color to use in Figure 8-4 for N rate recommendations. Dry weight in 36 inches of row (g) Row spacing in inches 5 6 7 8 ≤ 10 15 20 25 30 35 ≥ 40 fields are defined as those with 84 to 157 grams dry weight per square yard. High biomass fields have more than 167 grams dry weight per square yard. Step 4: Don’t Let a Sulfur or Potassium Deficiency Rob Wheat Yield Potential Sulfur-deficient wheat does not assimilate N fertilizer efficiently so it is important to make sure adequate sulfur (S) is available at growth stage 30. In addition to the percent N content, the NCDA&CS plant report also gives levels of other plant nutrients, including S. These levels can be checked against the critical values shown in Table 8-2. A tissue S content less than 0.25 percent, or an N-to-S ratio greater than 15, indicates that S is limiting and the wheat will likely benefit from an application of 20 to 30 lb S per acre at growth stage 30. North Carolina coastal plain wheat producers who have deep sandy soils can also use the growth stage 30 tissue test to optimize potassium (K) fertilizer inputs. This is especially important for producers who may have skipped or reduced preplant potash for their wheat and for the following double-cropped soybeans. Ideally, growers who have wheat on deep sandy soils should submit both a growth stage 30 tissue sample and a diagnostic soil sample from the same field. Tissue K levels of less than 2 percent indicate that the wheat crop is deficient. If the soil sample also shows low K-index levels, K will be needed as soon as possible for the wheat crop, and certainly before the subsequent soybean crop is planted. Wheat Tissue Test Examples Low Wheat Biomass Example The plant report shows the biomass sample weighed 8 grams and the tissue sample had a N content of 3.5%. The wheat was planted in 6-inch rows. Table 8-1 indicates the BLUE line in Figure 30 Nitrogen Management 0 10 20 30 40 50 60 70 80 90 100 110 120 2.0 2.5 3.0 3.5 4.0 4.5 5.0 GS-30 N Recommendation (lb/acre) Percent N In Tissue At GS-30 N Recommendations For Low biomass wheat Medium biomass wheat High biomass wheat Virginia tissue test Figure 8-4. Growth stage 30 N rate recommendations based on the new NC wheat tissue test. Table 8-2. GS-30 whole plant tissue sample nutrient sufficiency levels. Nutrient P K Mg S B Zn Mn Cu ------ % ------ ------ ppm ------ Sufficient level 0.25 2 0.1 0.25 3 12 20 3 8-4 is the correct one to use as this is a low biomass wheat field. Finding 3.5% on the horizontal axis of Figure 8-4 and using the BLUE line show the recommended N fertilizer rate is 71 lb per acre. Thin wheat fields could result from late planting or from fall temperatures that were too low to promote tillering and growth. In fields like this, the VA (dashed line) and NC system (BLUE line) make very similar N rate recommendations. Medium Wheat Biomass Example The plant report shows the biomass sample weighed 25 grams and the tissue sample had a N content of 3.5%. The wheat was planted in 7-inch rows. Table 8-1 indicates the RED line in Figure 8-4 is correct for N fertilizer rate recommendations as this is a medium biomass wheat field. Finding 3.5% on the horizontal axis of Figure 8-4 and using the RED line show the recommended N fertilizer rate is 46 lb per acre. In medium biomass fields, the VA system (dashed line) tends to overestimate the N fertilizer rate required to optimize yield and economic return, especially for wheat with N content greater than 3.5%. High Wheat Biomass Example The plant report shows the biomass sample weighed 36 grams and the tissue sample had a N content of 3.5%. The wheat was planted in 7-inch rows. Table 8-1 indicates the GREEN line in Figure 8-4 is correct for N fertilizer rate recommendations as this is a high biomass wheat field. Finding 3.5% on the horizontal axis of Figure 8-4 and using the GREEN line show the recommended N fertilizer rate to be 0 lb per acre. High biomass fields can result from high carry-over N from a previous crop, fall manure application, or unusually warm fall and winter weather that promoted excess tillering. In these fields, the VA system (dashed line) overestimates the growth stage 30 nitrogen fertilizer rate. Oats, Barley, Triticale, and Rye Research on using tissue samples to optimize N requirements for these crops has not been done. Use Table 8-3 to determine the crop's total spring N requirement. Nitrogen Management 31 Table 8-3. Spring N recommendations for oats, barley, triticale, and rye. Region Spring N Fertilizer (pounds per acre) Oats Barley Triticale Rye Coastal Plains 100 100 120 80 Piedmont & Mountains 80-100 80 120 80 Tidewater 100 100 120 80 9. Nutrient Management for Small Grains Carl Crozier, Ron Heiniger, and Randy Weisz Routine Soil Testing to Prevent and Manage Nutrient Deficiencies Soil testing before planting is an essential component of a small grain fertility management program. Different fields can vary so widely in pH and nutrient levels that it is impossible to predict optimum application rates without soil test results. It is much more economical to prevent yield losses associated with nutrient deficiencies than to try to correct them once visible symptoms appear. Producers should sample each field once every two to three years at the same time of the year, preferably in the early fall. Often this is done before a corn or cotton crop, which tends to be more sensitive to applied nutrients than small grains. However, if you suspect a nutrient problem, then sample more frequently before a small grain crop and use that information to adjust nutrient applications. Sample boxes, information sheets, test results, and recommendations are provided free of charge by the Agronomic Division of the NCDA&CS, and guidelines for soil testing procedures can be found in another Extension publication: SoilFacts: Careful Soil Sampling – The Key To Reliable Soil Test Information (www.soil.ncsu.edu/ publications/Soilfacts/AG-439-30). Diagnostic Soil Sampling and Plant Tissue Analysis When abnormal growth or plant color is observed, it is often useful to obtain diagnostic samples to determine if there is a nutrient deficiency. If samples are collected to diagnose an observed problem rather than for routine purposes, then separate samples should be submitted to represent the surface soil (0 to 4 inches) and the subsoil (4 to 8 inches). Tissue analysis can determine whether an adequate amount of fertilizer has been applied or if a particular nutrient is limiting crop growth. Plant tissue analysis is particularly useful in determining a crop’s need for mobile nutrients, such as nitrogen, sulfur, and boron; and for diagnosis of deficiency symptoms for manganese, copper, or zinc. To take a tissue test, clip a handful of plants above the ground with 8 to 10 samples collected from both the problem area and a corresponding area of normal growth. When taking diagnostic samples, both soil samples and plant tissues from the affected "bad" area and a nearby unaffected "good" area should be submitted for analysis to the NCDA&CS diagnostic laboratory. Soil pH and Lime Recommendations Proper pH is critical in obtaining good crop growth and yield. Small grains grow best when the pH is near the target level for each soil class. If pH is too low, soluble aluminum and acidity can limit root growth and nutrient uptake. If pH is too high, micronutrients such as manganese, iron, copper, and zinc can become unavailable. Stunted growth, nutrient deficiency symptoms, and low yield are the most common problems associated with soil pH levels that are not maintained in the proper range. Often nutrient deficiencies are the result of low or high pH rather than a lack of adequate amounts of the nutrient in the soil. Ideal soil pH levels vary based on soil type. Target levels are 6.0 for mineral soils, 5.5 for mineral organic soils, and 5.0 for organic soils. When the soil pH is below these targets, apply lime as early as possible in the production year to allow time for neutralizing soil acidity. Liming rates and the type of lime applied cannot be determined based on soil pH alone; they also depend on residual soil acidity, residual credit for recently applied lime, and measurement of available magnesium. For more information see SoilFacts: Soil Acidity and Liming for Agricultural Soils 32 Nutrient Management (www.soil.ncsu.edu/publications/Soilfacts/ AGW-439-50/SoilAcidity_12-3.pdf ). Phosphorus Recommendations Phosphorus (P) plays a key role in germination and early plant growth, promotes winter hardiness, stimulates the growth of the wheat kernel, and has a role in determining when the plant reaches maturity. Phosphorus Deficiency Symptoms Purpling of the leaf margins and bottom leaf surfaces of the lower plant leaves and purpling of the leaf sheaths at the stem’s base are symptoms of P deficiency. Slow growth or stunting is another sign of P deficiency. Phosphorus-deficient plants are slow to mature, and green heads are often found in spots in the field at harvest. Deficiency symptoms are often found on waterlogged, cool soils in late winter or early spring. Phosphorus Fertilizer Rates As noted previously, a good soil test is the best way to determine fertilizer requirements. The following P recommendations are made only as guidelines and should not replace soil testing as the primary means of determining crop nutrient needs. A wheat crop yielding 40 bushels per acre typically requires 40 pounds of P2O5 (25 pounds in the seed and 15 pounds in the straw). Mineral soils, such as those found in the NC coastal plain and piedmont, bind P and prevent it from leaching. Heavy organic soils do not bind P, resulting in a movement of P to the lower soil horizons or to drainage waters. Soils high in clay content, such as those found in the piedmont, bind P very tightly, making it unavailable to the crop. Consequently, both heavy organic soils and soils high in clay content often test low in available P even though high amounts of P fertilizer are applied every year. Care must be taken on these soils to apply P in a way that limits the interaction between the P fertilizer and the soil. Because animal wastes are high in P, soils where heavy applications of animal waste have been applied will have high levels of available P. Table 9-1 shows the recommended rates for P fertilizer in the different regions and major soil types of the state. Phosphorus Placement and Timing Phosphorus should be broadcast on the soil just before planting. Growers farming heavy organic or clay soils should limit the amount of soil-fertilizer contact (and thus reduce nutrient binding), which means little to no tillage should occur after a P application. Potassium Recommendations Potassium (K) influences grain quality (including test-weight) and oil content, prevents lodging, and plays an important role in drought and disease tolerance. Potassium Deficiency Symptoms The most common deficiency symptom for K in small grains is stunted growth and early lodging. Plants with a K deficiency will have low vigor, poor drought or disease tolerance, and reduced kernel size. Under severe K deficiency, the leaf tip and margins on the lower leaves will bronze and eventually turn yellow and die. Deficiency symptoms are more likely on deep sandy soils or soils that are waterlogged and compacted. Potassium Fertilizer Rate A wheat crop yielding 40 bushels per acre typically requires 64 pounds of K2O (16 pounds in the seed and 48 pounds in the straw). Because so much of the K in the plant is in the straw, most of it will be recycled in the soil. Most of the agricultural soils in NC have adequate to high levels of available K. In particular, soils where animal waste has been applied will be high in available K. The exception to this rule is that available K is low on sandy soils in the NC coastal plain and tidewater. Sandy soils do not bind K, so the K leaches below the root zone. Nutrient Management 33 Potassium Placement and Timing Potassium should be broadcast just prior to planting. On sandy or very sandy soils with a high leaching potential, K should be applied in two applications, half at planting and the other half just prior to growth stage 30 when N is applied. There is no benefit to applying K to a growing crop after growth stage 31. 34 Nutrient Management Table 9-1. Critical macronutrients for small grain production. Element Common deficiency symptoms Common fertilizer forms 1 Basis for fertilizer rate Suggested rates per acre if soil test data are not available2 Notes Phosphorus (P) Stunting, purpling on margins of lower leaves or on leaf sheaths, delayed maturity Granular monoammonium phosphate (MAP, 11-52-0) Granular diammonium phosphate (DAP, 18-46-0) Liquid ammonium phosphate (10-34-0) Soil test Coastal plain mineral soils: 0 to 30 lbs P2O5 Tidewater organic soils low P index: 30 to 50 lbs P2O5 Piedmont clay soils, shallow topsoil: 30 to 40 lbs P2O5 Limit the amount of soil-fertilizer contact on heavy organic or clay soils. Potassium (K) Lower leaf tip and margin burn, weak stalks, lodging at harvest, small ears, slow growth Potassium [plus chloride (muriate 0-0-60), sulfate, nitrate, hydroxide, or magnesium sulfate] Soil test Sandy or very sandy soils: 50 to 60 lbs K2O Organic soils (only if K is deficient): 50 to 60 lbs K2O Mineral or clay soils: (only if K is deficient): 50 to 60 lbs K2O On deep sand, apply just before planting or split apply at planting and at growth stage 30. Calcium (Ca) Terminal and root tip damage, dark green, weakened stems, ear disorders Lime, calcium sulfate (gypsum) Soil test Apply lime at recommended rate. Generally OK if limed to target pH. Magnesium (Mg) Interveinal chlorosis in older leaves, leaf curling, margin yellowing Dolomitic lime, magnesium sulfate (epsom salt), potassium magnesium sulfate, magnesium oxide Soil test, tissue analysis If needed: 20-30 lb Mg Generally OK if dolomitic lime used. Sulfur (S) Yellowing of young leaves, small spindly plants, slower growth and maturation Elemental sulfur; sulfate [plus ammonium, calcium (gypsum), magnesium (epsom salt), potassium, potassium magnesium]; Ammonium thiosulfate; Sulfur-coated urea Tissue analysis or soil criteria Sandy soils low in S: 15 to 25 lb S Deficiency likely if sandy surface is 18+ inches deep. 1 This table does not list all available chemical forms of fertilizers or recommend use of any specific form. Percent chemical analyses included are examples only, and may not reflect the composition of any specific commercial source. 2 Soil samples should be taken to avoid underestimating or overestimating actual needs. Sulfur Recommendations Sulfur (S) increases kernel weight, kernel size, grain protein, yield, and test-weight. Sulfur is required for the production of chlorophyll and many enzymes involved in the utilization of N. Consequently, a small grain crop must have adequate amounts of S to use N fertilizer property. Sulfur Deficiency Symptoms Symptoms of S deficiency include yellowing of young leaves, small spindly plants, slowed growth, and delayed maturation. Sulfur deficiency looks very much like N deficiency except that with S deficiency the young leaves at the top of the plant are the first to turn yellow. Sulfur deficiency symptoms usually occur in patchy spots across the field. Generally, S deficiencies are only found on deep sandy soils. However, in recent years, S deficiency symptoms have occurred in clay and organic soils during cool, wet weather when the plant is small. Periodic checks in the late winter and early spring can help identify fields with S deficiency. Sulfur Fertilizer Rate A wheat crop yielding 40 bushels per acre typically requires 10 pounds of elemental S (4 pounds in the seed and 6 pounds in the straw). While most of the agricultural soils in NC will have adequate to high levels of available S, sandy soils with low levels of organic matter usually are deficient in S because S is water soluble and easily leached. On sandy, S deficient soils, 15 to 25 pounds S per acre can be applied at planting or with the N sidedress. Sulfur should be applied before jointing to avoid crop damage and increase the likelihood of an economic response. Calcium and Magnesium Recommendations Calcium (Ca) deficiency symptoms include terminal and root tip damage, dark green stems, weakened stems, and poor ear formation. Magnesium (Mg) deficiency symptoms include interveinal chlorosis in older leaves, leaf curling, and yellowing of the leaf margins. Generally, Ca and Mg levels are maintained through dolomitic lime applications. If deficiencies occur and no pH change is desired, then sulfate forms such as gypsum (calcium sulfate) or epsom salts (magnesium sulfate) can be applied at the rates recommended in Table 9-1. Micronutrient Management Due to expense and the potential for toxicity, applications of micronutrients (including copper, manganese, and zinc) are generally not made to small grains unless they are specifically recommended by a soil test or if specific deficiencies are identified. Common problems often found in wheat in NC include manganese deficiencies on overlimed soils and copper deficiencies on organic soils. Copper Recommendations Proper levels of copper (Cu) in the plant enhance protein content of the kernel and grain yield. Copper Deficiency Symptoms Common Cu deficiency symptoms include stunting, leaf tip or shoot die-back, and poor upper leaf pigmentation. Perhaps the best way to diagnose a Cu deficiency is by observing the leaf tip. "Pigtailing" or "corkscrewing" of the leaf tip is a sign of Cu deficiency. Organic soils are naturally low in Cu, and often deficiency symptoms can be found in plants grown in these soils, particularly when the plant and root system are small. Wheat is very sensitive to Cu deficiency and will be one of the first crops to show symptoms. Copper Fertilizer Rate A wheat crop yielding 40 bushels per acre typically requires 0.04 pounds of elemental Cu per acre (0.03 pounds in the seed and 0.01 pounds in the straw). Table 9-2 shows the rate of Cu to use when a soil test detects a low level or when deficiency symptoms are noted. Growers should take care to avoid the over-application of Cu fertilizers since Nutrient Management 35 high concentrations of Cu can be toxic to the plant. Timing a Copper Application The recommended time to apply Cu is preplant. This avoids the high cost of Cu chelates, eliminates the chance of leaf burn, and allows a much longer residual effect. However, if deficiency symptoms occur, a foliar spray can be applied at much lower rates than are recommended for soil applications. Usually, Cu chelates or organic dusts are recommended for foliar application. Do not apply Cu after jointing. Manganese Recommendations Proper levels of manganese (Mn) in the plant enhance plant growth and the production of chlorophyll. 36 Nutrient Management Table 9-2. Critical micronutrients for small grain production. Element Common deficiency symptoms Common fertilizer forms 1 Basis for fertilizer rate Suggested rates per acre if soil test data are not available2 Notes Copper (Cu) Stunting, leaf tip/shoot dieback, poor upper leaf pigmentation Copper sulfate, copper oxide, copper chelates Soil test, tissue analysis If deficient: apply 0.25 lb Cu to foliage with 0.50 lb of hydrated lime, or 2-8 lb3 Cu to soil. Boron (B) Leaf thickening, curling, wilting; reduced flowering/ pollination Boric acid, borax, solubor, borates Tissue analysis Avoid toxicity, apply only as needed. Iron (Fe) Interveinal chlorosis of young leaves Ferrous sulfate, ferric sulfate, ferrous ammonium sulfate, iron chelates Tissue analysis Manganese (Mn) Upper leaves pale green or streaked Manganese sulfate, manganese oxide, manganese chelate, manganese chloride Soil test, tissue analysis Coastal plain, sandy soil or any soil with Mn index less than 25: 10 lb Mn If deficient: apply 0.5 lb Mn to foliage, or 10 lb Mn to soil. Overliming decreases availability. Zinc (Zn) Decreased stem length (rosetting), mottling-striping, interveinal chlorosis Zinc sulfate, zinc oxide, zinc chelates, zinc chloride Soil test, tissue analysis If deficient: apply 0.5 lb Zn to foliage, or 6 lb Zn to soil. 1 This table does not list all available chemical forms of fertilizers or recommend use of any specific form. Percent chemical analyses included are examples only, and may not reflect the composition of any specific commercial source. 2 Soil samples should be taken to avoid underestimating or overestimating actual needs. 3 NCDA guidelines are 2 lb Cu/ac or 6 lb CuSO4/ac for mineral soils, 4 lb Cu/ac or 12 lb CuSO4/ac for mineral-organic soils, and 8 lb Cu/ac or 24 lb CuSO4/ac for organic soils. Manganese Deficiency Symptoms Manganese deficiency symptoms include stunting, gray specks in the leaf, and pale to almost whitish upper leaves or streaked yellowing (interveinal chlorosis) of the upper leaves. Manganese deficiency can be distinguished from a Mg deficiency in that Mn affects the upper leaves while Mg affects the lower leaves. Manganese deficiencies commonly occur in overlimed soils (pH greater than 6.5 on mineral soils or greater than 6.1 on mineral-organic or organic soils) with low cation exchange capacity. A common situation where Mn deficiencies are noted is the over-limed areas at the ends of the field where the spreader truck turned or where lime was stockpiled. Manganese Fertilizer Rate A wheat crop yielding 40 bushels per acre typically requires 0.25 pounds of elemental Mn (0.09 pounds in the seed and 0.16 pounds in the straw). Sandy soils in the NC coastal plain are typically low in available Mn. Table 9-2 shows the rate of Mn to use when soil test levels are low or when deficiency symptoms are noted. Timing of Manganese Fertilizer Application The best time to apply Mn on soils with low test levels is preplant. However, to correct a deficiency if the soil pH is high, use a foliar application. Manganese is commonly supplied as manganese sulfate, manganese oxide, and manganese chelates or organic complexes. Manganese chelates and organic complexes are recommended only for foliar application due to soil reactions that tend to convert the Mn to unavailable forms. Application of foliar fertilizers may have to be repeated several times to correct severe deficiency symptoms on fields that have been overlimed. Once wheat is jointing, consider whether response to fertilizer is likely to outweigh crop damage due to traffic. Zinc Recommendations Zinc (Zn) deficiency symptoms include decreased stem length (rosetting), mottling, and interveinal chlorosis. Zinc deficiencies are most common if the soil pH is greater than 6.5 and the soil phosphorus index is greater than 75. As with other micronutrients, recommended rates (Table 9-2) are lower for foliar applications, but residual effects are greater with soil applications. Special Consideration for No-Till Production Before a field is placed in 100 percent no-till production, it should be soil tested and brought to target pH and optimum nutrient levels. Once adequate fertility levels are achieved throughout the root zone, no-till production can begin. Long-term no-till studies suggest that yields and soil fertility can be maintained even though lime and fertilizer are applied to the soil surface without incorporation. Routine soil samples in established no-till fields should be collected to a depth of 4 inches. Use of starter fertilizers containing N and P are more important in no-till production because plant development is delayed. Special Consideration for Precision Agriculture Currently, precision agriculture is being used for three primary reasons: (1) to identify areas in fields with different pH or soil test indexes, and vary lime and fertilizer rates accordingly; (2) to monitor and map crop yield and moisture content; and (3) to document material applications, including fertilizers and pesticides. The cost of collecting grid soil samples or using a yield monitor must be returned by decreasing the amounts of lime or fertilizer applied, increasing crop yield, reducing negative environmental impacts, or by some combination of these benefits. Growers are more likely to increase profits by using precision farming practices in situations where pH or fertility levels are limiting wheat yields. An examination of the variability in soil pH or fertility within a field should indicate the potential for increasing crop yield through variable-rate lime or fertilizer applications. If at least a fourth of the field area has soil nutrient indexes Nutrient Management 37 below 25, or pH levels below the target value for that crop and soil class, then it is likely that precision farming practices will increase wheat yields and profits. Special Consideration for Animal Wastes and Sewage Sludge Animal waste and sewage sludge can be excellent sources of nutrients and organic matter for a wheat crop. Organic forms of P can move deeper in soils than do inorganic fertilizer sources. Consequently, they can be advantageous in no-till or conservation tillage systems. When applying animal waste as a fertilizer material for wheat, all amendments should be tested before application to determine optimum application rates. Soils that are being fertilized with waste materials should be tested to determine nutrient levels. The amount of waste material applied should be based on the need for desirable nutrients, such as P or K, and the requirement that levels of P, Zn, Cu, cadmium, lead, and mercury should not exceed prescribed limits. Producers should rotate applications as much as possible to obtain nutrient benefits while minimizing excess nutrient and toxic metal accumulation. If you use lime-stabilized sludge or poultry litter, monitor the soil pH carefully to prevent overliming and possible Mn deficiency. Applications of animal waste are most effective when made prior to planting a small grain crop. However, topdress applications of poultry or swine manure can be done in January or early February with good results. Several good publications on application of animal waste and/or sludge can be found online: www.soil.ncsu.edu/publications/ extension.htm . 38 Nutrient Management 10. Insect Pest Management for Small Grains Dominic Reisig, D. Ames Herbert Jr., Gaylon Ambrose, and Randy Weisz Insect management can be critical to the economic success of a small grains enterprise, and growers should be aware of the various insects and management strategies and tactics. These techniques can help you prevent and detect some potentially serious insect problems before significant loss occurs. Aphids Aphids are small sucking insects that colonize small grains early in the season and may build up in the spring or fall. They injure the plants by sucking sap or by transmitting the barley yellow dwarf virus (BYDV). BYDV is a persistent virus that can be retained by the aphid for weeks and can be transmitted in minutes to a few hours of aphid feeding. Although the exact relationship between aphid numbers and direct yield loss is unknown, aphids must be very abundant before injury from sap-removal occurs. However, low aphid abundance early in the fall can result in high BYDV occurrence in winter cereals. Aphid flights in the fall from grasses surrounding cereals pose the most serious threat for this disease. Predicting aphid flights is difficult; flights are generally initiated from cues such as temperature, sunlight, and increasing daylength. Flights generally decrease as precipitation, relative humidity, and wind speed increase. Life Cycle Two species of aphids predominate in small grains: the English grain aphid (Photo 10-1) and the bird cherry-oat aphid (Photo 10-2). However, several others, such as the corn leaf aphid (Photo 10-3) and the greenbug (Photo 10-4), may be found occasionally. These aphids are described in Insect and Related Pests of Field Crops, AG-271 (http:// i p m . n c s u . e d u / AG 2 7 1 / s m a l l _ g r a i n s / small_grains.html). Aphids' high reproductive rate enables their populations to quickly build up to levels that can cause economic loss. However, aphid populations are usually kept in check by weather Insect Pest Management 39 Photo 10-1. English grain aphid. Photo by M. Spellman. Photo 10-2. Bird cherry oat aphid. Photo 10-3. Corn leaf aphid. Photo by Jack Kelly Clark. conditions and biological control agents, such as lady beetles, parasitic wasps, syrphid fly maggots, and fungal pathogens, which are often abundant in small grains. Management Aphids can occur throughout the growing season. In early-planted small grains, especially barley, low levels of aphids in the fall may transmit an infection of BYDV that can cause symptoms later in the season. Using a tolerant or resistant variety is an excellent management tactic. A list of the current wheat varieties that ar e r esistant to BYDV ( w w w. s m a l l g r a i n s . n c s u . e d u / _Mi s c / _VarietySelection.pdf) is available on the NC Small Grain Production Website (www.smallgrains.ncsu.edu). Insecticides (either as seed treatments or as a foliar application) to control aphids in the fall are generally not recommended. There are several situations, however, in which the use of insecticides can be beneficial. In areas with a chronic BYDV history, early-planted small grains may benefit from preventive neonicotinoid insecticide seed treatments (such as Gaucho, Cruiser, or NipsIt INSIDE). This may be important in the NC piedmont, as a recent study demonstrated that BYDV incidence can increase when wheat is no-till planted into corn residue. An alternative to using an insecticidal seed treatment is to make a foliar application of a long-residual pyrethroid insecticide at or before three- to four-leaf stage wheat. BYDV symptoms are easier to recognize in the spring than the fall. When aphid populations are relatively low in the fall, an insecticide application is justified only if BYDV is anticipated and freezing weather is not expected for at least one week. As cold weather begins, populations quickly decline. Scouting Scouting for aphids requires searching plants or examining heads on 10 samples taken at locations scattered across each field. Each sample should consist of all plants in 1 foot of row or 10 heads, depending on plant stage. For foliage examination, counting aphids on each sample is not feasible; instead, use a simple estimation technique. Initially, the scout must "calibrate" by visually establishing a mental picture of aphids on 1 row foot and then counting aphids over the entire plant to determine the actual number. After several repetitions of this exercise, aphid counting is no longer needed because a calibrated mental image is available. This mental image is then used to visually estimate populations in field scouting. Head-infesting aphids are similarly estimated, except in this instance the calibration exercise is done by using heads rather than whole plants. Threshold Aphids may become much more abundant in the spring than the fall. However, because plants are actively growing in the spring, they can support many more aphids without injury. Also, spring-transmitted BYDV usually does not seriously affect small grains. Consequently, the thresholds for applying insecticides are much higher in the spring compared to those for the fall (see Table 10-1). Armyworm Armyworm infests small grains, usually wheat, from late April to mid-May. They can cause serious defoliation, injury to the flag leaf, and also cause head drop. Armyworm populations fluctuate greatly 40 Insect Pest Management Photo 10-4. Greenbug. Photo by Alton N. Sparks, Jr., University of Georgia. from year to year and across areas of NC. Typically, the northeastern and mid-coastal counties experience the most consistent armyworm problems Life Cycle Armyworm moths are one of the first moths to become active during the spring. Moths prefer to lay eggs on various grasses, and small grains are very attractive. Thick planting, narrow row spacing, and high N rates promote dense and lush growth, which is conducive to high armyworm infestation. Young armyworm larvae are pale green, yellowish, or brown and have a habit of looping as they crawl. When they become larger (1 to 1½ inches), they are greenish-brown with pale white and orange stripes running down their bodies; the head is honeycombed with faint dark lines (Photo 10-5). The armyworm is described in Insect and Related Pests of Field Crops, AG-271 (http://ipm.ncsu.edu/ AG271/small_grains/small_grains.html ). Armyworm is the only caterpillar found in large numbers in small grains. They are active at night, hiding under plant litter (such as old corn stalks) and at the base of wheat plants during daylight hours. After dark, they feed on foliage from the bottom of the plant upward. As they eat the lower foliage or as it is destroyed by leaf pathogens, the armyworm larvae feed higher, eventually reaching the flag leaf. If populations are high, large caterpillars may also feed on the stem just below the head. Management Management of armyworm is based on scouting, thresholds, and resulting application of insecticides when necessary. Infestations of armyworms are not easily detected by casual observation because caterpillars hide during the day. Fortunately, several signs of armyworm infestation occur, and caterpillars can also be monitored if the correct technique is used. Blackbirds (grackles and red-winged blackbirds) commonly search for armyworms in small grains. Any field with significant bird activity should be scouted. Signs of armyworm leaf feeding and caterpillar droppings can also be good indicators. Feeding is sometimes inconspicuous because small caterpillars do not eat much and feeding signs are often concentrated on the lower part of the plant. When caterpillar Insect Pest Management 41 Photo 10-5. Armyworm. Photo by M. Spellman. Table 10-1. Aphid thresholds for small g grains in the fall and spring. Fall Spring Plant Height (inches) After heading 3 - 6 4 - 8 9 - 16 20 aphids per row foot, and BYDV has been a chronic problem or is expected, and cold weather is not forecast for at least one week. aphids per row foot 25 aphids per head and 90% of heads infested, or 50 aphids per head and only 50% of the heads infested 100 200 300 populations are high, droppings may be seen easily but should not be confused with weed seed. Scouting Fields should be scouted for armyworms in May when caterpillars are normally small. Thorough scouting should not be done until the caterpillars are at least 3/8-inch long because populations of small worms are difficult to estimate accurately and often die out. Once caterpillars reach 3/8-inch or more in length, take at least 5 samples per field (10 samples in larger fields of 20 acres and more) by examining all the wheat in 3 feet of one row. Look for and count the caterpillars in litter around the base of plants and under old crop residue. Pay special attention to fields in which birds are active. Fields should be scouted weekly until a treatment or no-treatment decision is made. Re-infestation of caterpillars in May after a successful insecticide application does not occur. Threshold The economic threshold is 6 half-inch or longer caterpillars per square foot. The threshold changes to 12 caterpillars per square foot when grain is near maturity. Cereal Leaf Beetle Cereal leaf beetle, a native to Europe and Asia, was first detected in Michigan in 1962. Since then, it has spread throughout most of the Midwestern and Eastern United States and has become a significant pest of VA and NC small grains. This insect can become very numerous in small grain fields, and the larvae may reduce grain yield by eating the green leaf tissue. Preferred small grain hosts for the larvae are wheat, oats, and barley, although the adults will feed on corn, wild grasses and all other cereals. Life Cycle Adult beetles (Photo 10-6) are about 3/16-inch long and have metallic looking, bluish-black heads and wing covers. The legs and front segment of the thorax are rust-red. Adults overwinter in grasses, ground litter, or other debris, within wooded areas, or in other protected sites in the vicinity of last season’s grain fields. In the spring, they emerge when the temperature is 48 to 50°F to feed, mate, and lay eggs in small grain fields. Eggs (Photo 10-7) are elliptical, about 1/32 of an inch long, and yellow when newly laid, but later become darker to orange-brown and finally black before hatching. Most often the eggs are laid singly or end-to-end in short chains on the upper leaf surface between, and aligned with, the leaf veins. Egg laying occurs during March and into April with more larvae found in poorly tillered small grain fields. Females lay 100 to 400 eggs each. These eggs will hatch in about 5 days. Larvae (Photo 10-8) are slug-like and have yellowish bodies with heads and legs that are brownish-black. However, body coloration is usually obscured by a black globule of mucus and fecal matter held on the body, giving the larvae a shiny black, wet 42 Insect Pest Management Photo 10-6. Cereal leaf beetle adult. Photo 10-7. Cereal leaf beetle eggs. appearance. Larvae develop in 10 to 12 days. Peak larval populations occur in mid-April to early May. Upon reaching full size, they dig ½ to 2 inches into the ground and pupate. Pupation usually lasts 15 to 20 days. Injury to Small Grains Although adults will feed on young small grain plants, their feeding does not affect the plant's performance. However, larvae eat long strips of green tissue from between leaf veins and may skeletonize entire leaves (Photo 10-9), leaving only the transparent lower leaf tissue. Severely defoliated fields can take on a white "frosted" cast (Photo 10-10) as green tissue is lost on the upper leaves. Yield Reduction Leaf feeding indirectly reduces the plant's ability to make its food and limits reproductive growth, particularly if the upper leaves are destroyed. Larger larvae are by far the most damaging. Yield reductions of 10 to 20 percent are typical in infested commercial fields. Yield reductions of 45 percent have been observed when defoliation was near 100 percent and the damage occurred early in the heading period. Damage late in the head-fill period does not have a great impact. Scouting Method • Take samples at a minimum of 10 random sites in the interior of the field (avoid the edges). At each site, examine 10 stems for eggs and larvae. This will result in 100 stems per field being examined. • Eggs may be on the leaves near the ground. Record the number of eggs and larvae counted at each sample site and then calculate the total number of eggs and larvae found in the field. • If there are more eggs than larvae, scout again in five to seven days. This is important because egg mortality can be very high. A large number of eggs does not necessarily mean there will be a high larvae population. Insect Pest Management 43 Photo 10-8. Cereal leaf beetle larva. Photo 10-9. Wheat leaf damage caused by cereal leaf beetle larvae feeding. Photo 10-10. A wheat field severely damaged by cereal leaf beetle feeding. • If there are more larvae than eggs, there is no need to scout again. A decision about applying an insecticide for control can now be made. Threshold When the scouting results show that there are more larvae than eggs, peak egg laying has passed and it is the correct time to use the spray threshold. If there are 25 or more eggs plus larvae on 100 stems, the threshold has been met. Management Tips Cereal leaf beetle adults are attracted to dense highly-tillered wheat fields, but more larvae per tiller are found in poorly-tillered fields. Management practices that lead to densely tillered stands by mid- February can help to reduce the risk of having a cereal leaf beetle infestation. These practices include planting on-time, using high quality seed planted at recommended seeding rates, making sure that preplant fertility is adequate for rapid fall growth, and applying a split nitrogen application in February and March if additional tillering is needed in the spring. Cereal leaf beetle is easily controlled with low rates of many insecticides if they are applied when the threshold is met. Because only one generation hatches per year, if insecticides are applied based on the use of thresholds, one application will give adequate management. However, if insecticides are applied early before threshold levels are met (such as with top-dress nitrogen), reduced application rates may not be adequate. And even when full label rates are used, a second application may be required later in the season. Insecticides labeled for cereal leaf beetle control in small grains are listed in Table 10-2. To be most effective, insecticides must be applied by early head-fill, before the larvae cause significant yield-reducing defoliation. In making a choice about insecticides, consider the presence of aphids or armyworms. Both carbamates and pyrethroids kill aphid parasites and predators. Carbamates can sometimes allow a serious aphid increase. Therefore, a carbamate should not be applied against cereal leaf beetle if aphids are a potential threat. Carbaryl, beta-cyfluthrin, lambda-cyhalothrin, and zeta-cypermethrin provide excellent management, with good residual effects at least 14 days after treatment. Spinosad provides adequate management under normal situations, with minimal residual effects. Under heavy pressure situations, using spinosad is equivalent to doing nothing. 44 Insect Pest Management Table 10-2. Insecticides labeled for cereal leaf beetle management (2013). Although they may be as effective as the chemicals listed here, generic formulations are not listed nor are pre-mixed products with multiple insecticide classes. Insecticide Class Active Ingredient Trade Name Formulation/A Carbamates methomyl Lannate LV 1 to 2 pt Lannate SP 0.25 to 0.5 lb carbaryl Sevin brand XLR PLUS 1 pt Pyrethroids beta-cyfluthrin Baythroid XL 1.0 to 1.8 fl oz lambda-cyhalothrin Karate Z or Warrior II 1.92 fl oz Karate or Warrior 2.6 fl oz zeta-cypermethrin Mustang Max EC 1.6 to 4.0 fl oz Hessian Fly Why Has Hessian Fly Become a Problem? In recent years, numerous NC fields have suffered extensive losses because of Hessian fly infestations. Historically a wheat pest in the Midwest, changes in field-crop production including early planted wheat, increased adoption of no-tillage double-cropped soybeans, and the use of wheat as a cover crop for strip-tillage cotton and peanut production have permitted the Hessian fly to reach major pest status in NC. Hessian Fly Life Cycle The adult Hessian fly is a small, long-legged, two-winged insect that resembles a small mosquito (Photo 10-11). It is one of many species of gnat-sized flies that may be found in wheat fields. The female Hessian fly adult is reddish-brown and black in color and about 1/8-inch long. The slightly smaller males are brown or black. The elliptical eggs are very small and orange. Eggs are deposited singly or end-to-end in “egg lines” between the veins on the upper surface of the young leaves (Photo 10-12). Newly hatched larvae (maggots) are also orange for 4 or 5 days before turning white (Photo 10-13). As larvae mature, a translucent green stripe appears down the middle of the back. The maggot is about ¼ inch long when full grown. The maggot transforms into an adult fly inside a dark-brown case, or puparium, that resembles a flaxseed in size and shape. Newly formed puparia will be a lighter-brown color that transforms to a mahogany-brown color with age. Puparia or "flaxseeds” (Photo 10-14) are located under leaf-sheaths and usually below ground on young tillers or below the joint in older plants. Hessian fly can be found in small numbers in most wheat fields at harvest. If the wheat stubble is destroyed after harvest, the fly dies and the life cycle is broken (Figure 10-1). If, however, the wheat stubble is left in the field, the fly can survive as “flaxseeds” in the stubble through the summer. In late August and September, adults emerge from the “flaxseeds” and lay eggs on volunteer wheat or on early planted cover-crop wheat. A first generation can be completed on these plants, and the next generation adults emerging from cover-crop or volunteer wheat plants can lay eggs on wheat planted for grain in October and November, before Insect Pest Management 45 Photo 10-11. An adult Hessian fly. Photo 10-12. Hessian fly eggs. Photo 10-13. Large Hessian fly larvae. the weather turns cold enough to kill the adult flies. Often Hessian flies begin depositing eggs very soon after seedling emergence. Once Hessian flies are established on a new wheat crop, their eggs hatch within a few days and the tiny maggots migrate into the whorl of small wheat plants, ultimately locating below ground at the stem’s base, where they enter the pupal stage. While feeding, the larvae injure the plants by rupturing leaf or stem cells. They cause the plant to form an area of nutritive tissue around the base to enhance their feeding, which can result in tiller stunting and dieback. A heavy infestation on early-stage plants may greatly reduce plant stand. A new generation of adults usually emerges in March depending on the weather, lays eggs, and produces new larvae that migrate to the stem joints where they feed and cause further injury. This spring injury may kill the wheat, but usually only results in weakened stems, small heads, and poorly filled grain heads with low-quality kernels. Often, wheat lodges in seriously infested fields. 46 Insect Pest Management Photo 10-14. Hessian fly puparia or “flaxseed”. < No-till beans allows pupa to over-summer 3rd generation adults re-infect wheat plants Pupae overwinter in tillers Maggots kill fall tillers Maggot feeding causes lodging Summer Autumn Winter Spring Disking before beans kills pupae & ends the life cycle Pupae in wheat straw at harvest Eggs laid on volunteer wheat, grassy weeds or early planted cover-crop wheat 1st generation adults emerge in soybean fields & seek new host 2nd generation adults emerge & seek wheat planted for grain Figure 10-1. The Hessian fly life cycle. Management Rotation Because the Hessian fly life cycle depends largely on the presence of wheat stubble, rotations that prevent new wheat from being planted into or near a previous wheat crop’s stubble will be an effective way to prevent infestations. Avoid planting wheat into last season’s wheat stubble! Continuous no-tillage wheat, double-cropped with soybeans, may result in severe problems and should be avoided in Hessian fly problem areas. Additionally, since the Hessian fly is a weak flier, putting distance between the location of new wheat plantings and the previous season’s wheat fields can be a successful method of preventing new infestations. Although Hessian fly can become serious under other situations, most serious infestations occur when wheat is planted early into wheat stubble or into fields next to wheat stubble. Tillage: Disking wheat stubble after harvest effectively kills the Hessian fly. Planting soybean no-till into wheat stubble enhances Hessian fly survival by preserving the site where puparia spend the summer. Burning wheat straw will reduce puparia, but many puparia are found below the soil surface. Therefore, burning is not as effective as disking and is not recommended as a management method. Choosing Cover Crops Serious Hessian fly infestations have occurred where wheat for grain was planted near early-planted wheat for cover or where early-planted wheat was present for dove hunting. In cropping systems where cover crops are used, such as in strip-till cotton or peanut production, the use of other small grains besides wheat will reduce Hessian fly populations. Although Hessian fly can develop on grasses in more than 17 genera, some are more favorable hosts for egg laying and development. Oats, rye, and triticale are not favorable for Hessian fly reproduction and do not serve as a nursery, making these grains preferable over wheat for cover cropping in areas where wheat for grain is also produced. If triticale is used for cover cropping, varieties that are adapted to NC should be planted. Delayed Planting Because freezing temperatures kill Hessian fly adults, a traditional method for preventing Hessian fly infestation is to delay planting until after the first freeze (often called the fly-free date). This concept has not worked well in NC because an early freeze is not a dependable event. Often a “killing freeze” does not occur until December in many areas of NC, after most growers need to have wheat planted for agronomic purposes. There is no reliable fly-free date in North Carolina. Resistant and Tolerant Varieties Correct varietal selection is probably the most inexpensive and effective method of Hessian fly management (Photo 10-15). Many wheat varieties are advertised as having Hessian fly resistance. Unfortunately, in most cases, resistance is based on a single gene present in the variety that must match a gene in the Hessian fly. This resistance often works by causing cell death and fortification of the cell wall around the nutritive tissue where the Hessian fly feeds. To be effective in NC, wheat varieties must be specifically resistant to the local Hessian fly genotype. A list of the current wheat var i e t i e s that ar e r e s i s tant t o He s s ian f l y ( w w w. s m a l l g r a i n s . n c s u . e d u / _Mi s c / Insect Pest Management 47 Online VIDEO: Identifying & Managing Hessian Fly www.smallgrains.ncsu.edu/hessian-fly.html _VarietySelection.pdf) is available on the NC Small Grain Production Website (www.smallgrains.ncsu.edu). In most cases, varieties rated as having “good” resistance should provide enough protection to avoid economic losses due to Hessian fly. In areas with severe Hessian fly problems, however, the use of resistant and tolerant varieties may not be sufficient to prevent infestations from occurring. Systemic Se |
OCLC number | 11058462 |