Blossom-End Rot of Tomato, Pepper, and Watermelon
Vegetable Disease Information Note 19 (VDIN-0019)
Charles W Averre, Extension Plant Pathologist
P. B. Shoemaker, Extension Plant Pathologist
Blossom-end rot is a nonparasitic disease of tomato, pepper and watermelon. Losses can vary from a trace to more than 50 percent.
After tomatoes are planted, good results have been obtained by spraying foliage and stems with anhydrous calcium chloride (4 pounds per 100 gallons of water per acre) four times on a weekly schedule beginning when the second forms, or when symptoms first appear. Calcium chloride solutions are also available under several trade names for small scale garden use. Application in the same tank with fungicides and/or insecticides is suggested. This helps to rapidly place calcium directly where it is needed in the fruits. Do not exceed the recommended rate. Calcium chloride is suggested only for tomatoes. Application should be done while temperatures are cool in the morning
Since blossom-end rot is so closely related to extremes in the water supply, an important aid in control is to regulate moisture supply in the soil. Cultivation and hoeing can be avoided if proper weed-control chemicals are used. If cultivation is necessary, it should be shallow to avoid root pruning. Mulching, which serves to maintain an even supply of soil moisture, should be practiced where feasible. If irrigation of any kind can be used, it may prove profitable during hot, dry weather. To reemphasize, either an inadequate or excess moisture stress favors blossom-end rot development. In general, plants need at least one inch of water per week in the form of rain or supplemental irrigation.
Young plants should not be grown too quickly nor should the plants be subjected to severe "hardening-off" before transplanting. A steady growth rate as a seedling and in the field will discourage this trouble.
affected fruits when symptoms are first observed may be worthwhile for
subsequent development of other fruit on the plant. This is particularly
recommended for tomatoes.
North Carolina Cooperative Extension Service
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of specific chemicals are based upon information on the manufacturer's
label and performance in a limited number of trials. Because environmental
conditions and methods of application by growers may vary widely, performance
of the chemical will not always conform to the safety and pest control
standards indicated by experimental data. All recommendations for pesticide
use were legal at the time of publication, but the status of registration
and use patterns are subject to change by actions of state and federal
regulatory agencies. 10/93