Watermelon mosaic is caused by the watermelon mosaic virus type 2. It affects cucurbits and peas, alfalfa, vetch, clover and a few other plants. The virus is widespread, and is found on all continents. It has been known since the 1930's. Symptoms can vary depending on the plant species.
Leaves are malformed, mottled yellow and green, and blistered.
Watermelon fruit can be misshapen, dwarfed, mottled, or spotted. Muskmelon plants may produce few fruit. Uniform green to dark green mosaic or mottling occurs on leaves. Fruit are shortened, gnarled and sometimes knobby. Leaves have a faint green to severe yellow mottle, and may be malformed puckered or blistered.