Cucumber mosaic virus
An aphid-spread virus that causes mottled, puckered leaves and stunted plants in cucumbers, melons, squash and many other plants.
Also known as: CMV
Symptoms and identification
Young leaves are mottled yellow and green, puckered and smaller than normal, and may have a shoestring look in tomatoes. Plants are stunted, flowers drop and fruit are small, warty or mottled and bitter.
Causes
More than 80 species of aphid carry the virus from plant to plant within seconds as they probe leaves. It lives in over 1,000 plant species, including weeds, and in some seed.
Organic treatment
Remove and bin infected plants straight away. Wash tools and hands. Spraying aphids with insecticidal soap or neem is of limited help because they spread the virus very fast.
Prevention
Control aphids and weeds, use resistant varieties and virus-tested seed, and consider reflective mulch or fine mesh to keep aphids away from young plants.
Chemical treatment (use with care)
No chemical cures a virus, and insecticides rarely stop spread because aphids transmit it so quickly.