• Worldwide distribution. On zucchini and other cucurbits, including melon, pumpkin, watermelon, as well as species of Luffa and Momordica. Important diseases.
• Four viruses infect zucchini and others in the cucumber family, causing misshapen fruit and leaves.
• All are spread by aphids (green flies). After a short feed the aphids can infect healthy plants.
• Cultural control: avoid over-lapping crops, check each seedling; weed around nursery and plants in field; plastic mulches (clear and silver) delay infection; resistant varieties.
• Chemical control: none recommended because aphids spread virus quickly before insecticides kill them. But try soap, white or horticultural oils (see Fact Sheet no. 056).

Zucchini yellow mosaic

Zucchini yellow mosaic virus, Zucchini yellow mosaic potyvirus. The virus exists as many strains.

Zucchini yellow mosaic virus is not alone in causing mosaics in zucchini and other cucurbits, there is Watermelon mosaic virus and Papaya ringspot virus type W. Watermelon mosaic virus causes mosaics (light and green patterns) on the leaves, whereas the other two distort both leaves and fruit. Cucumber mosaic virus also infects zucchini producing stunted distorted leaves, and surface roughness of the fruit.