Symptoms on plants with cucumber mosaic diseases can vary, but in general, plants show an overall lighter color along with mosaic patterns (alternating light and dark green areas) on at least some leaves, especially on the younger leaves. Often, the main leaf vein is distorted and somewhat zigzag in appearance. Plants generally show stunting, leaf curling, and mosaic, and mature leaves can develop necrotic areas shaped like oak leaves. Fruit may be malformed and have conspicuous concentric rings or spots.
CMV affects many types of vegetables including melons, tomatoes, celery, peppers, spinach and beans.
CMV is usually spread by infected aphids or contaminated tools. In order to control aphids, you need to encourage aphid predators into your garden and to control ants.
Whenever possible, try planting CMV resistant varieties. Clear your garden of weeds with can harbor the disease. Remove infected plants as soon as possible to slow the spread of the disease to healthy plants. There are no known effective treatments for CMV.
Source: http://ipm.ucanr.edu/PMG/r116102011.html
