Department of Horticultural Science
Horticulture Information Leaflet 8107-A
12/97
BLOSSOM-END ROT OF TOMATOES
IN THE HOME GARDEN
Douglas C. Sanders, Extension Horticultural Specialist
Distributed in furtherance
of the Acts of Congress
of May 8 and June 30, 1914.
Employment and program
opportunities are offered to
all people regardless of
race, color, national origin,
sex, age, or disability.
North Carolina State University,
North Carolina A&T State
University, U.S. Department
of Agriculture, and local
governments cooperating.
Blossom-end rot of tomatoes is a
physiological disorder caused by a lack of
sufficient calcium in the blossom end of
the fruit. This disorder results in the decay
of tomato fruits on their blossom end. Dry
brown or tan areas the size of a dime, that
grow to the size of a half dollar, characterize
this disorder. This disorder is usually
most severe following extremes in soil
moisture (either too dry or too wet).
To reduce blossom-end rot in tomato,
implement the following steps:
1. Lime tomato soils to pH 6.5 to 6.7
- Home gardens not limed in the past
2 to 3 years will need 2 cups of lime
for each plant. The lime should be
worked into the soil 1 2 inches deep.
To determine the exact amount of
lime, send a soil sample to the
Agronomic Division, Blue Ridge
Road Center, N.C. Department of
Agriculture, Raleigh, N. C. 27611,
for analysis and recommendations.
2. Fertilize properly - Applying too
much fertilizer at onetime can result
in blossom-end rot. Following soil
test recommendations is the best
way to insure proper fertilization.
For home gardens not soil tested,
apply 5 pints of 8-8-8 per 100 ft of
row, and thoroughly work it into the
top 8 inches of soil.
3. Mulch plants - Use straw, pine
straw, decomposed sawdust, ground/
decomposed com cobs, plastic, or
newspapers. Mulches conserve
moisture and reduce blossom-end
rot. In extreme drought, plastic may
increase blossom-end rot if plants
are not watered.
4. Irrigate when necessary - Tomato
plants require about 1.5 inches of
water per week during fruiting. This
amount of water should be supplied
by rain or irrigation. Extreme
fluctuations in soil moisture result in
a greater incidence of blossom-end
rot.
5. Spray calcium -The plants may be
sprayed with acalcium solution using
calcium nitrite or calcium nitrate or
calcium chloride at 4 level Tbsp per
gal of water. This spray should be
applied 2 to 3 times a week, beginning
at the time the second fruit clusters
bloom. These materials can be mixed
with the spray that is used for control
of foliar diseases. Chelated calcium
solutions also provide an excellent
source of calcium. When using these
chelates, follow label directions.
Several foliar spray materials
containing calcium are available and
all work well for tomatoes.
Additional Information
Plant Pathology Information Note (VDIN-019): Blossom-end Rot of Tomato, Pepper
and Watermelon. URL http://www.ces.ncsu.edu/depts/pp/notes/
North Carolina
Cooperative Extension Service
NORTH CAROLINA STATE UNIVERSITY
COLLEGE OF AGRICULTURE & LIFE SCIENCES
