Cucurbit Family Plant Problems - Mosaic Virus

Mosaic on squash. Insert: Mosaic on cucumbers.

CMV of cucumber - fruit mottle.

CMV of summer squash.

WM-2 of summer squash - leaves.

WM-2 of muskmelon - leaves.


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. Or the skins may be smooth and completely white. Summer squash may also be covered with warts.

ANALYSIS: Mosaic virus

This plant disease is caused by several viruses that attack cucumber, muskmelon, and summer squash plants. 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 they can infect plants at any time from the seedling stage to maturity. Infection early in the season is more damaging. Infected fruits taste bitter. Fruits that are more than half grown at the time of infection are immune to attack. Roots are not affected.


There are no chemical controls for virus diseases. Remove and destroy all infected plants immediately. Control aphids and cucumber beetles by using an insecticide containing diazinon. Repeat at intervals of 7 to 10 days if the plants become reinfested. Remove weeds in and near the garden. Grow resistant cucumber varieties. There are not yet any resistant varieties of summer squash or muskmelon.

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Text and images adopted from theOrtho Problem Solver
Last Updated: Fri Sep 06 10:30:00PM CST 1996

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