Sulfur also controls mites but do not apply on squash and other vine crops. Control other insects by using insecticides such as diazinon, malathion, Sevin or endosulfan which can be legally used on the appropriate crop. Avoid the blanket use of any specific insecticide. Otherwise, insects may become resistant to the insecticide. It is a good idea to switch insecticides periodically.
Insects can be harmful, but disease can be disastrous.
Diseases must be prevented, not cured. There are two main diseases which cause this disaster every spring. Early blight is characterized by irregular, brown spots that first appear on older foliage. With age, the spots show concentric rings forming a target pattern. A yellow, diffuse zone is formed around each spot.