Capsicum & Chilli
Symptoms of Chilli Leaf Curl Virus are characterized by upward curling of leaf margins, yellowing of veins and reduction of leaf size. Additionally, leaf veins become swollen with shortening of internodes and petioles. Older leaves become leathery and brittle. If plants are infected during the early season, their growth will be stunted, resulting in significant yield reduction. Fruit formation in susceptible cultivars is rudimentary and distorted. The virus causes similar symptoms as the feeding damage of thrips and mites.
Symptoms are caused by begomovirus, which is primarily transmitted through whiteflies in a persistent manner. They are characterized as 1.5 mm long, waxy white wings with a pale yellow body and are frequently found on the lower side of the leaves. The spread of the disease depends on the wind condition, which will indicate how far the whiteflies can travel. Whiteflies are most problematic in the mid-to-late season. Since the disease is not seed-borne, the virus persists in the landscape via alternative hosts (such as tobacco and tomato) and weeds. Some additional factors that can favor the development of the disease are recent rainfall, infected transplants, and the presence of weeds. In nurseries, chilli plants are most prone to infection during the seedling and vegetative stages.
Control whitefly populations to reduce transmission of the virus. Neem oil or horticultural oils (petroleum-based oils) can be used. Make sure the oils thoroughly cover the plants, particularly the lower side of the leaves where whiteflies are most likely to be found. Some natural enemies such as lacewings, big-eyed bugs, and minute pirate bugs can control whitefly populations.
Always consider an integrated approach with preventive measures together with biological treatments, if available. There are no known effective methods for preventing or reducing chilli leaf curl virus. Follow chemical control methods, such as imidacloprid or dinotefuran. Spray seedlings with imidacloprid or lambda-cyhalothrin before transplanting to control the vector. Excessive use of insecticides will harm beneficial insects and also make many whitefly species to become resistant. To prevent this, ensure proper rotation between insecticides and use only selective ones.