Tomato Leaf Curl Virus Control

Symptoms

Leaves curl upward and inward, become small, thick, leathery and crinkled with yellowing between the veins. Plants infected when young remain severely stunted and bushy with shortened internodes. Flowering is poor and very few or no fruits set, and any fruits that form stay small and hard. The disease spreads in patches and is worst in the warm dry months when whiteflies are active.

Damage

This is one of the most destructive virus diseases of tomato and chilli in India and can cause yield losses of 30 to 100 percent when plants are infected early. There is no cure once a plant is infected, so all damage comes from preventing healthy plants from getting infected. The virus is carried only by the whitefly Bemisia tabaci, not by touch or tools, so controlling the whitefly and removing infected plants is the heart of management.

Organic & cultural control

Raise seedlings under a 40 mesh nylon net or insect proof nursery to keep whiteflies away during the most sensitive stage. Uproot and destroy infected plants as soon as you see curling so they do not act as a virus source. Install yellow sticky traps at 10 to 12 per acre to monitor and trap whiteflies. Spray neem oil at 5 ml per litre or neem seed kernel extract at 5 percent repeatedly to repel and check whiteflies. Grow a tall barrier crop of maize or sorghum around the field and remove weed hosts like congress grass and datura from bunds.

Chemical control

There is no chemical that cures the virus, so chemicals are used only to control the whitefly vector. Soil application or seedling root dip with imidacloprid at the nursery stage protects young plants, and foliar sprays of insecticides such as diafenthiuron, pyriproxyfen or spiromesifen are used in the field when whitefly numbers rise. Rotate between different insecticide groups to avoid resistance because whitefly develops resistance quickly. Always follow the product label dose, observe the pre harvest interval and consult your KVK or 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

Grow tolerant or resistant hybrids recommended for your area as this is the most reliable defence. Use clean insect proof nurseries, transplant only healthy seedlings and keep a strict watch for whiteflies from the seedling stage. Remove and destroy infected plants and weed hosts regularly. Use reflective or silver mulch to repel whiteflies, follow a crop free period to break the whitefly cycle, and avoid planting next to old infected tomato, chilli or cotton fields.