California avocado growers face challenges from several insect and disease pests. The industry's main pests, avocado thrips and persea mite, appeared in California in 1990 and 1996, respectively. As a result, more than four decades of largely pesticide-free insect control ended and many avocado growers now find it necessary to spray their orchards to minimize foliage and fruit damage. Root rot, collar rot and sunblotch are important avocado diseases found in almost all production areas.