A gray fungus is apparent on the lower leaf surface, particularly in wet humid weather. Viral Diseases are the most limiting factor to squash production, particularly during summer and fall months. There are several viruses that cause diseases in squash. Symptoms include a mosaic pattern on leaves that in severe cases causes a shoestring effect. Warty green areas can appear on the fruit of yellow summer squash.
Aphids are soft-bodied insects that often appear in clusters.
They suck plant juices and transmit viral diseases. Cucumber Beetles are bright yellow beetles with either black stripes or spots on their wing covers. Pickleworms are the caterpillar stage of a moth. Masses of orange-yellow eggs can be seen on the underside of leaves. They emit a disagreeable odor when crushed.