Colletotrichum Fruit Rot (fungus – Colletotrichum melongenae): Lesions on the fruit vary from small spots to one-half inch in diameter. The tissue is sunken, with an area filled with a flesh-colored ooze of fungal spores. Spots vary from one to several on the fruit surface. Severely infected fruit drop to the ground with the pedicel still attached to the plant. The fungus overwinters in plant residue and grows at temperatures of 55oF to 95oF with optimum growth at 80oF. Rainfall and overhead irrigation favor disease development. The fungus develops when the humidity is 93 percent or above. Although field sanitation is important, a preventive fungicide spray program is required during periods favorable for disease development.
Early Blight (fungus – Alternaria solani): This disease can be destructive on eggplant at any time in the life of the plant. It can cause seedling dieback known as collar rot. Later infection is on the foliage beginning on the lower part of the plant and developing upward. Spots are characterized by concentric rings which give a target appearance. Plants which are well fertilized and irrigated are not as susceptible. Infection of the fruit pedicels may cause a premature fruit drop. It requires eight to 10 days after infection before visible symptoms develop to the extent that epidemic levels are reached. Injured fruit are more subject to attack by the fungus than healthy fruit. Infection occurs between 60oF and 90oF. Long rotations, weed control, adequate fertilizer, and irrigation (furrow) will help reduce losses. Use clean seed and follow a thorough spray program when this disease is a problem.
Leaf Spot and Fruit Rot (fungus – Phomopsis vexans): This disease is characterized by circular brownish spots on fruit and leaves. On the fruit, soft, sunken spots become rotted and shriveled. Spray with approved fungicide beginning when fruit is first set and repeat at 10-day to two week intervals until fruit is nearly mature. Use a three year crop rotation. Florida High Bush, Florida market and Florida Beauty are resistant.
Wilt (fungus – Verticillium albo-atrum): The pathogen attacks nearly 200 species of plants but eggplant and okra are the two most seriously affected vegetables. Young plants appear normal, but become stunted as they develop. Severely affected plants turn yellow. The lower foliage wilts and defoliation occurs. Symptoms continue to progress until death occurs. When the stem is cut, there is a dark brown, discolored band around the vascular system. Infection occurs directly through the root hairs. The fungus survives for indefinite periods in the soil. Survival is aided by weeds which are susceptible to the fungus. Infection takes place when the temperature ranges from 55oF to 86oF. Verticillium is favored in its development if the soil is alkaline. Some development takes place at pH of 5.0 but all growth is stopped at a pH of 4.0. Control involves the use of long rotations. Cotton gin trash should be avoided or be well composted if used.
Yellows (Tobacco Ring Spot Virus): The disease causes yellowing and whitening of upper leaves. Later, entire plant becomes yellow and may die. Avoid planting in fields where yellows have occurred and, if warranted, fumigate soil to control nematodes. The dagger nematode is a known vector of the virus.