No garden, despite the gardener’s best efforts, is immune to pests and diseases. Even a well-tended one may have destructive organisms that will fly, crawl, creep, leap, or stroll into the garden from adjacent areas. Some will even ride on the winds and air currents from miles away. Gardens are microcosms where plants, insects, bacteria, fungi, earthworms and many other organisms live and thrive. Many of these inhabitants live in harmony with each other. Only a few cause problems for the rest of the garden community.
For detailed information on many plant diseases and pests go to the UC IPM Pest Note Index.