BLOSSOM-END ROT Page 1
MANAGING BLOSSOM-END ROT Publication
IN TOMATOES AND PEPPERS Number
AUTHOR: Cindy Fake, Horticulture and Small Farms Advisor, Nevada & Placer Counties
B lossom-end rot can cause
significant crop losses in
tomatoes and peppers, especially
BER in Tomatoes
Susceptibility to blossom-end
In terms of management,
blossom-end rot is primarily
a water issue. It is most severe
rot varies among tomato
early in the season. Eggplants following drought stress or wide
varieties. Fast growing cultivars
may also be affected and fluctuations in soil moisture.
with extensive foliage and
occasionally watermelons. determinate cultivars, which set BER is usually an early season
Symptoms all their fruit in a short period, problem, and the first fruits are
are frequently affected. Pear or most severely affected. As a
Roma tomato cultivars seem to result, it can have significant
rot (BER) is a
be among the most susceptible, economic
followed by some beefsteak and impacts,
salad types. Cherry tomatoes are as early
causes a dark,
rarely affected. fruits
sunken area on the lower
(blossom) end of tomato, Peppers are generally not as
pepper, and eggplant fruits. On susceptible to BER as
peppers, it may also occur on tomatoes, but larger, thick
the sides of the fruit, near the walled varieties may be affected.
blossom-end. The discoloration The disorder is not very A number of events factor into
is usually tan, brown, or black common in eggplant. early season blossom-end rot.
and should not be confused with These include rapid plant
Causes of BER
sunscald, which causes a whitish growth, development of a large
or translucent discoloration. Blossom end rot starts when the leaf area with a high
demand for calcium in the transpiration rate, rapid fruit
Secondary pathogens may infect expanding fruit exceeds the enlargement, and temporary
the BER-affected area, causing supply. However, it is not a case water stresses as the weather
overall fruit rot. In dry foothill of a simple calcium deficiency, fluctuates.
summers, the area becomes dry but is much more complex.
and leathery and is rarely Fruits in the rapid expansion
Adding calcium to the soil rarely
infected by pathogens, leaving phase (⅓ to ½ of full size) are
alleviates the problem. BER
the rest of the fruit intact. very susceptible to water stress.
involves a low level of calcium
However, blossom-end rot is Even a temporary water stress
in the fruit, but often the supply
unsightly and reduces the in this period can induce
may be more than adequate in
marketability of the fruit. blossom-end rot because water
the plant or soil.
preferentially goes to the leaves,
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BLOSSOM-END ROT Page 2
reducing calcium delivery to the the developing fruit also declines, Often, BER incidence will decline
developing fruit. High levels of contributing to the onset of as the season progresses, which
calcium are needed for cell BER. may lead growers to believe that
growth and strong cell walls, so applications of calcium have been
Calcium-related plant disorders
when a rapidly expanding fruit is effective. However, a reduction
can also result from restricted
deficient, tissues break down, in BER is more likely due to
leaving the dry, sunken lesions transpiration can occur when soil slowing of vegetative growth,
characteristic of blossom-end rot. changes in weather, or better
moisture is inadequate so the
Calcium and Transpiration plant shuts its stomata and
ceases to move water. Since Soil applications of calcium are
Calcium is a critical player in
calcium moves with the generally not very effective
blossom-end rot, but is only one
transpiration stream, its because BER is seldom induced
of several factors (Taylor et al.
movement also stops. by soil calcium deficiency. UC
2004). Calcium is dissolved in the
Transpiration can also be researchers have shown that
soil solution, taken up by plant
restricted in cool or cloudy most California soils contain
roots, and then moves through
weather because the atmospheric adequate plant-available calcium
the xylem from the roots to the
demand for moisture is low. and that commonly used soil
Thus, early plantings of tests systematically
tomatoes, especially those underestimate calcium in the soil
planted into cold soil, are often solution. The most common test
water in the
subject to blossom-end rot. for soil calcium, an ammonium
acetate extraction, actually
does not The Role of Other Nutrients
provides almost no information
move in the A calcium deficiency in the fruit about calcium availability to the
phloem. may also result from other plant. A saturated paste
Under conditions of high factors. Excess nitrogen extraction is a better test, but it
evaporative demand, i.e. low stimulates vegetative growth, still underestimates calcium in
relative humidity and high increasing the leaf area and thus the soil solution by a factor of 5
temperature, water moves the amount of transpiration from (Hartz et al. 2007.).
rapidly to the leaves, where most leaves. Potassium (K),
transpiration occurs. The calcium magnesium (Mg) and ammonium Foliar applications of calcium are
also unlikely to affect blossom-
is carried along with the water, so -nitrogen (NH4-N) all compete
most calcium absorbed by the with calcium for uptake into the end rot incidence. In the plant,
plant ends up in the leaves. Fruit plant, so high concentrations of calcium only moves with water in
the xylem. It has no ability to
do not transpire as much as those nutrients may reduce the
move through the phloem from
leaves; therefore less calcium amount of calcium available in
leaves to fruit, thus it cannot
reaches the fruit, which can cause the fruit.
move from the application site to
a localized calcium deficiency. Because of the perception that the fruit where it is needed.
The transpiration rate of the BER is an overall calcium
fruit is further reduced after the deficiency, many growers add
waxy cuticle develops, when the calcium to the soil or apply foliar
fruit is about ½-¾” in diameter. calcium. This rarely has an
With decreased transpiration, the impact on the disorder, but does
amount of calcium moving into add to the cost of production.
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BLOSSOM-END ROT Page 3
Managing Blossom-end Rot temperatures and References
evaporation, thus moderating
Blossom-end rot can be Bell Pepper Production in
soil moisture fluctuations.
prevented with good soil California. 2008. Tim
management and careful 5. Avoid cultivating close to Hartz, et al. UC ANR
monitoring of soil moisture so as plants so as to prevent feeder Publication #7217. http://
to limit stress. root damage that may restrict ucanr.org/freepubs/
water flow during hot periods. docs/7217.pdf
Blossom-end rot: A calcium
6. Calibrate nitrogen deficiency. 2004. Taylor,
applications to actual plant M.D. and S.J. Locascio. J.
use. Avoid over-fertilizing as Plant Nutr. 27(1):123-139.
rapid plant growth induced
by high N can contribute to Blossom-end rot and
BER. Tomatoes use a Calcium Nutrition of
maximum of about 200 Pepper and Tomato. 2009.
Strategies to Reduce pounds of nitrogen per acre. J. Mayfield and W. Kelley.
Blossom-end Rot Depending on soil, and The University of Georgia
environmental conditions, Cooperative Extension.
1. Cover crop or incorporate http://pubs.caes.uga.edu/
less may be appropriate.
compost to increase soil caespubs/pubcd/C938/
organic matter and diminish 7. Use nitrate forms of nitrogen C938.html
soil moisture fluctuations, rather than ammonium.
especially in decomposed Blossom-end rot incidence of
Excess ammonium in soils tomato as affected by
granite soils. reduces calcium uptake and irrigation quantity,
may exacerbate blossom-end calcium source, and
2. Use tensiometers or matrix
rot. reduced potassium. 2004.
blocks to monitor soil
moisture. Do not allow soil to Taylor, M.D., Locascio, S.J.,
8. Unless soil tests clearly
completely dry out when and M.R. Alligood.
indicate calcium deficiency in
tomato fruit are expanding Hortscience 39(5):1110-
your soil, soil applications of
rapidly. Schedule irrigations 1115.
calcium will probably not
to maintain moist, but not reduce the problem. If you Blossom End Rot of Tomato.
wet, soil conditions. For have a high magnesium soil Vegetable Crop Fact Sheet
determinate cultivars, once (and a pH below 6.5), liming 735. 1979. A. Sherf and T.
the fruit are more than half of may be useful to increase the Woods. Cooperative
full size, some water stress ratio of calcium ions to other Extension, New York State,
can be tolerated and will competitive ions in the soil. Cornell University. http://
improve flavor. vegetablemdonline.ppath.cor
9. Foliar applications of calcium nell.edu/factsheets/
3. Reduce plant stress by are of little value as calcium is Tomato_BlossRt.htm
irrigating before periods of poorly absorbed by leaves
high heat. and does not move easily in Blossom end rot of tomato.
the plant. 2000. Hansen, M.A.
4. Use organic mulch along Publication 450-703W.
plant rows to reduce soil Virginia Cooperative
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BLOSSOM-END ROT Page 4
Extension Plant Disease mag/farming_no_easy_fixes/
Factsheets. http:// Soil Calcium Status Unrelated to
pubs.ext.vt.edu/450/450- Tipburn of Romaine Lettuce.
703/450-703.html 2007. Hartz ,Timothy K. et
Blossom-End Rot of Tomato, al. HortScience 42 (7):1681-
Pepper, and Eggplant. 1684.
Factsheet HYG-3117-96. S.
Miller, R. Rowe, & R. Riedel.
The Ohio State University
Blossom-End Rot of Tomato,
Pepper, and Watermelon.
2000. Charles W Averre and
P. B. Shoemaker. North
Extension Service. http://
Blossom End Rot of Tomatoes
and Other Vegetables.
2002. Martin A. Draper,
Rhoda Burrows, and Steven
Munk. South Dakota
Extension Fact Sheet 909.
Effects of environment on the
uptake and distribution of
calcium in tomato and on the
incidence of blossom-end rot,
pp. 583-588. 1993. Adams, P.
and L.C. Ho. IN: M.A.C.
Fragoso and M.L. van
Optimization of plant
nutrition. Kluwer Academic
No easy fixes seen for vegetable
calcium disorders. 2006. Dan
Bryant. Western Farm Press.
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