Zucchini yellow mosaic virus

Zucchini Yellow Mosaic Virus (ZYMV) is an aphid-borne potyvirus, regarded as a major pathogen of cucurbits in most regions of the world where these crops are cultivated.

ZYMV affects all cucurbits including pumpkins, squashes, vegetable marrows, courgettes, melons, watermelons, cucumbers, gherkins and various gourds. The effects are severe leaf mosaic, yellowing and eventually "shoestring" symptoms in the leaves. The fruits are stunted, twisted and deformed by raised protuberances, which make them unmarketable. In cultivated crops plants cease producing marketable fruits within 1-2 weeks of infection and serious financial losses can occur, particularly in courgette and marrow crops.

Control
The disease may be introduced in infected seed, so sourcing clean seed can help prevent the disease. Control is largely dependent either on using insecticides to control the aphid vectors. A form of "inoculation" or cross protection may also be used where seedlings are inoculated with a non-virulent strain of the virus (ZYMV-WK); this prevents infection with the severe strain.