Problem Identifier Unit Screen//v.w/ RR Template

Problem Identifier Unit Screen//v.w/ RR Template Mosaic Virus

Cucumbers, gourds, muskmelons, pumpkins, summer squash, watermelon, winter squash

Problem
Leaves are mottled yellow and green, and are distorted, stunted, and curled. Cucumber fruits are mottled with dark green and pale green to white blotches and covered with warts. Sometimes the skin is smooth and completely white. Summer squash fruit may be also covered with warts.

Analysis
This plant disease is caused by several viruses that attack cucumbers, musk-melons, and summer squash. The viruses overwinter in perennial plants, and weeds, including catnip, pokeweed, wild cucumber, motherwort, and milkweed. The viruses are spread from plant to plant by aphids and cucumber beetles, and can infect plants at any time from the seedling stage to maturity. Infection early in the season is more damaging. Affected fruits taste bitter. Fruits that are more than half-grown at the time of infection are immune to attack.

Solution
There are no chemical controls for virus diseases. Remove and destroy all infected plants immediately. Control aphids and cucumber beetles with an insecticide containing diazinon. Repeat at intervals of 7 to 10 days if the plants become reinfested. (For more information on controlling disease-carrying insects, see Vectors of Plant Diseases.) Remove weeds in and near the garden. Grow resistant cucumber varieties. (For a list of these varieties, see Slicing Cucumbers Resistant to Diseases.) There are not yet any resistant varieties of summer squash or muskmelon.

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