Whitefly and Yellow Mosaic Virus Control

Symptoms

Tiny white winged insects rest on the underside of leaves and fly up in a cloud when disturbed. The virus they carry causes bright yellow and green mosaic patches that start as small yellow spots and spread until leaves turn almost completely yellow. Infected plants are stunted, flower poorly and set few small distorted pods. Early infection can leave plants nearly barren.

Damage

Yellow mosaic is the most serious disease of moong, urad and soybean in India and can cause yield losses from 30 percent up to almost total loss when plants are infected early. The whitefly Bemisia tabaci spreads the virus from plant to plant, so disease spread depends directly on whitefly numbers. The earlier a plant is infected, the greater the loss.

Organic & cultural control

Since the virus cannot be cured, focus on the whitefly vector and on removing sources. Uproot and destroy infected plants as soon as you spot mosaic to stop spread. Install yellow sticky traps at 10 to 12 per acre to trap whiteflies. Spray neem seed kernel extract 5 percent or neem oil to repel and check whiteflies. Conserve natural enemies and avoid early broad-spectrum sprays that kill them.

Chemical control

There is no chemical cure for the virus itself, so chemicals are used only to control the whitefly vector. Treat seed with imidacloprid 600 FS for early protection, and spray recommended insecticides such as imidacloprid 17.8 SL, thiamethoxam 25 WG or diafenthiuron when whitefly numbers rise. Rotate groups to avoid resistance. Always follow the product label for dose and pre-harvest interval and consult your KVK or an agronomist before use.

Always follow the product label, the recommended pre-harvest interval, and your local KVK or agronomist. Pesticide approvals change, so verify before use.

Prevention

Grow resistant or tolerant varieties such as Pusa Vishal and Samrat in moong and resistant urad varieties, as this is the most effective and cheapest control. Sow on time and avoid late sowing when whitefly is high. Treat seed with imidacloprid for early cover. Remove volunteer and weed hosts around fields. Avoid growing moong, urad and soybean continuously which keeps the virus alive year round.