Alternaria leaf spotCaused by: Alternaria macrospora
Problem Category: Fungal Disease
Symptoms: Small, circular brown lesions on cotyledons and seedling leaves which expand and develop a concentric pattern; necrotic areas coalesce and often have a purple margin; centers of lesions may dry out and drop form the plant creating a "shot-hole" appearance on the leaves.
Comments: Plants stressed by drought, nutrient deficiency and other pests are more susceptible to the disease; fungus spreads rapidly in dense canopies, especially during periods of warm, wet weather.
Management: Plow crop residue into the soil to reduce inoculum levels; provide plants with adequate irrigation and nutrients, particularly potassium; applications of appropriate foliar fungicides may be required on susceptible cultivars.
Control: spray 5% cowurine +Asafoetida solution.