Cucurbit chlorotic yellows

Cucurbit chlorotic yellows (CCYV) is a severe viral disease caused by a virus belonging to the genus Crinivirus in the Closteroviridae family. This pathogen is a significant threat to agriculture, causing systemic infection that impairs the plant's ability to produce energy and maintain normal growth cycles.

The disease primarily affects members of the Cucurbitaceae family. Major crop hosts include watermelon, cucumber, melon, zucchini, and squash. In addition to commercial crops, several weed species can act as symptomless reservoirs for the virus, facilitating its survival in the environment across different seasons.

The characteristic symptoms of the disease include interveinal chlorosis, which initially appears on the older leaves and gradually spreads across the entire foliage. Affected leaves may become brittle and distorted. The systemic nature of the infection leads to stunted growth, poor fruit development, and a marked reduction in total yield and sugar content, making the produce unmarketable.

The virus is transmitted in a semi-persistent manner by whiteflies, specifically Trialeurodes vaporariorum and Bemisia tabaci. The whitefly acquires the virus after feeding on an infected plant and can transmit it to healthy hosts within a few hours. The spread of the disease is highly correlated with the population dynamics of these insect vectors, which thrive in warm and humid greenhouse conditions.

Managing Cucurbit chlorotic yellows requires an integrated pest management (IPM) strategy focused on vector suppression and sanitation:

• Aggressive management of whitefly populations using systematic insecticide programs and yellow sticky traps.
• Removal and destruction of weeds in and around greenhouses to eliminate virus reservoirs.
• Implementation of physical barriers such as insect-proof screens to exclude whiteflies.
• Strict crop hygiene and sanitation practices to prevent the carry-over of the virus between crop cycles.
• Regular field scouting to identify and remove infected plants immediately upon the appearance of initial symptoms.