Important diseases of greengram are root rot, wilt, leaf spot, powdery mildew, bacterial leaf spot, leaf curl, leaf crinkle and yellow mosaic virus.
Among these, yellow mosaic virus (YMV) is a major observed disease in pulses during recent years.
It is the most destructive disease during all seasons. It results in heavy crop loss from 50 to 70 per cent, especially if the disease occurs in the early stages of crop growth. It affects crops like blackgram, soyabean and other pulse crops too.
Initially small yellow patches or spots appear on the young leaves. Slowly the area of yellow discoloration increases and the entire leaf may turn yellow.
Infected leaves show alternating green and yellow patches. Yellow leaves turn slowly dry and wither. Infected plants mature late. Flower and pod production get reduced.
Pods in the infected plants are small size, turn yellow and get distorted. Early infection causes death of the plant before seed set.
Infection causes reduction in plant yield and quality of grains. Diseased plants have stunted growth. This disease is transmitted by whitefly.
Seeds are to be treated with insecticides like carbosulfon at 30gm or monocrotophos at 5ml per one kg seed before sowing.
Follow crop rotation and maintain soil health management. Grow suitable region wise resistant varieties. Use seeds collected from disease-free plants.
— Infected plants should be removed.
— Remove and destroy disease-affected leaves/plants from crop fields to avoid secondary spread.
— Destroy host weeds. Intercrop with non host crops like sorghum, pearl millet and maize.
— Control of white fly by spraying insecticides viz., dimethoate 0.03 per cent or monocrotophos 1.6 per cent or metasystox (0.1 per cent) or triazophos 1.25 ml/l at the initial stage of disease proves effective.
— If the disease is not controlled, apply second spray at an interval of 7-10 days.
— Foliar sprays of methyl demeton 2ml/l also control the vector spread.
(Dr. Arshanapally Vijaya Bhaskar Rao, Scientist ( Plant Pathology), email:email@example.com, mobile: 098498 17896, Regional Agricultural Research Station ,Warangal, Acharya N.G.Ranga Agricultural University, Hyderabad, Telangana.)