A soft, wet rot will develop after affected areas of fruit are invaded by decay fungi and bacteria. Internal hardening, discoloration, and tissue collapse may be present without the characteristic external symptoms of blossom end rot. Typical lesions on blossom end of tomato fruit. Although blossom end rot is the result of a calcium deficiency in fruit, environmental conditions that interfere with uptake and availability of water and nutrients can contribute greatly to symptom expression. Excessive nitrogen fertilizer also can contribute to blossom end rot by promoting vigorous vine growth and depleting available calcium in the soil.
Tomato varieties differ in their resistance to blossom end rot.
When environmental conditions favor blossom end rot, fruit of all varieties will show symptoms. Cluster of processing tomatoes damaged by blossom end rot. Blossom End Rot Management Incidence of blossom end rot can be reduced by following recommended soil management practices. A representative soil sample should be submitted for analysis each year so that proper amounts of fertilizer are applied and calcium-deficient soils can be amended. Irrigation with 1 acre inch of water per week is usually sufficient.