Watermelon curly mottle

Watermelon curly mottle is a destructive viral disease caused by members of the begomovirus genus. It significantly affects the development of cucurbit crops, leading to severe stunting and economic loss. The disease disrupts the internal physiology of the plant, preventing normal growth and fruit development.

The primary causal agent is transmitted by insect vectors, specifically the silverleaf whitefly (Bemisia tabaci). These insects acquire the virus while feeding on infected plants and subsequently transmit it to healthy ones during the probing phase. Once the plant is infected, the virus spreads systemically through the phloem to all plant parts.

Symptoms are distinct and easily recognizable in field conditions. They include severe leaf curling, stunting of the main vine, and a characteristic mosaic or yellowing pattern on the foliage. The internodes become shortened, giving the plant a bushy appearance. Affected plants produce fewer flowers and fail to set fruit properly.

Environmental conditions play a crucial role in disease epidemiology. Hot, dry weather is ideal for whitefly proliferation, which leads to increased disease transmission rates. During such periods, the virus can spread rapidly throughout a commercial field, especially if weed hosts are present in nearby margins.

Management strategies must be integrated to be effective. Farmers should focus on:

• Early detection and roguing of infected plants;
• Managing insect vectors using appropriate insecticides;
• Maintaining field hygiene by removing alternative weed hosts;
• Utilizing resistant cultivars when available in the region.