Cucurbit chlorotic yellows

Cucurbit chlorotic yellows virus (CCYV) is a significant plant pathogen belonging to the genus Crinivirus within the Closteroviridae family. It primarily infects members of the Cucurbitaceae family, causing a condition known as Cucurbit chlorotic yellows. This disease has emerged as a major concern for both greenhouse and open-field growers globally due to its potential to severely impact crop yields.

The characteristic symptoms of CCYV infection involve interveinal chlorosis on the older and middle leaves of the host plants. As the disease progresses, the chlorotic areas expand, often leading to yellowing of the entire leaf, upward curling of leaf margins, and eventual senescence. The impaired photosynthetic capability directly leads to stunted plant growth, fruit deformation, and reduced fruit quality.

The biological cycle of the virus is strictly linked to its insect vectors, specifically the sweetpotato whitefly (Bemisia tabaci) and the greenhouse whitefly (Trialeurodes vaporariorum). Transmission is semi-persistent, meaning the whiteflies acquire the virus after feeding on infected plants and can transmit it to healthy plants for several days. Importantly, the virus is not known to be seed-borne or mechanically transmitted.

Development and spread of the virus are highly dependent on the population density of its whitefly vectors. High temperatures and the presence of reservoir hosts, such as weed species or infected neighboring crops, significantly accelerate the spread. Once introduced into a field or greenhouse, the rapid colonization of plants by whiteflies can lead to a widespread outbreak in a short period.

Effective management and control measures focus on breaking the transmission cycle:

• Implementing strict integrated pest management (IPM) to control whitefly populations.
• Using insect-proof screening on greenhouse vents to prevent vector entry.
• Eliminating reservoir weeds and promptly removing symptomatic plants to reduce the inoculum source.
• Applying systemic insecticides or biological control agents (e.g., predatory wasps or fungi) to manage vector numbers.