Powdery mildew on melon leaf. Photo by Clemson University. Apply the first spray as soon as the disease appears. Mosaic Mosaic is caused by cucumber mosaic virus and squash mosaic virus. A patchwork or mosaic pattern of light and dark green forms on the leaves and fruits.
Leaves are small and puckered, and plants become severely stunted.
Cucumber mosaic symptoms on squash. Photo by Arden Sherf, Cornell University. Cucumber mosaic is very common. In addition to the mosaic pattern the edges of the leaves turn down, and the knobs on the fruits are light yellow. The cucumber mosaic virus is transmitted from plant to plant by several different kinds of aphids.