Peppers and eggplant are related to tomatoes, so they're susceptible to many tomato diseases as well as some of their own. There are some things a gardener can do to avoid diseased plants. Follow these practices in the garden to avoid plant diseases. Keep a close watch for insects, especially aphids. Plants that are weakened by insects are more susceptible to disease.
Insects can spread disease by carrying the disease organism on their bodies.
Weed your garden. Weeds can have blights and diseases that can spread to your healthy plants. Weeds will also harbor disease-carrying insects. Mow around the garden if weeds are plentiful. Stay out of the garden when it's wet.