Whitefly Control

Symptoms

Look under leaves for clouds of tiny white winged insects that fly up when the plant is disturbed. Leaves turn yellow, curl and become sticky with honeydew, on which black sooty mould grows. Heavily infested plants look weak and dull with reduced boll set.

Damage

Whitefly (Bemisia tabaci) sucks sap and weakens the plant, while its honeydew promotes sooty mould that reduces photosynthesis and stains the lint. Most importantly it transmits cotton leaf curl virus, which can cause severe yield loss. It is the most serious pest during hot summer months in north and central India.

Organic & cultural control

Install yellow sticky traps at 10 to 12 per hectare to catch adults. Spray neem oil 5 ml per litre or neem seed kernel extract 5 percent, repeating at about 15 day intervals. Use entomopathogenic fungi like Verticillium lecanii. Remove alternate host weeds, conserve natural enemies such as Chrysoperla and ladybird beetles, and avoid synthetic pyrethroids that flare up whitefly.

Chemical control

When populations cross the threshold, recommended actives such as diafenthiuron, flonicamid, pyriproxyfen, spiromesifen or acetamiprid can be used in rotation. Avoid synthetic pyrethroids and repeated use of the same chemical, which worsen whitefly. Always read and follow the product label, observe the pre-harvest interval, and consult your KVK or a qualified agronomist before spraying.

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

Prevention

Sow recommended tolerant varieties on time and avoid excess nitrogen and close spacing. Keep the field and bunds free of weeds that host whitefly and the virus. Avoid growing other host crops nearby, monitor regularly with yellow sticky traps, and protect natural enemies by spraying only when needed.