TECHNICAL DOCUMENT ON EARLY BLIGHT OF TOMATO

Among the fungal diseases affecting tomato crops, early blight caused by Alternaria solani Ellis and Martin is considered as one of the most devastating disease leading to an accountable losses. Early blight shows up as leaf blight on the lower part of plants. The disease moves upward, and by early to mid-summer, early blight has caused a "firing-up" of foliage over most of the tomato plants in the garden. As the disease progresses, leaves turn yellow, wither, and drop from plants. Defoliation reduces the photosynthetic rate and increases the respiration rate of healthy tissue. Tomato plants severely infected produce low yields of undersized fruit. Generally, fruit are also showing signs of sunscald since leaves are not present to protect fruit from direct sunlight. Early blight tends to start early in the spring when the weather is humid soon after transplants have set. These conditions are ideal for infection of young tomato plants by A. solani. However, probably the most important reason this disease is so common has to do with the tremendous popularity of tomatoes. Annual economic yield losses due to early blight have been estimated at about 80%. Currently, cultural practices and fungicide applications are employed for the management of early blight due to the lack of reliable resistant cultivars. This present technical document will deal with the current understanding of causal agents of early blight of tomato, symptoms and signs, epidemiology, ecology, disease development, disease cycle and disease management.