Controlling Spider Mites
Spider mites are about the size of the smallest object you can see with your eyes (0.1 to 0.5 mm). Despite their small size, these mites can cause significant plant injury.
Spider mite damage usually appears as a light speckling on leaves, followed by a general bronze discoloration. Heavy infestations can bronze an entire tree. The easiest way to diagnose spider mites is to tap an infested branch over a white piece of paper. Dislodged mites will appear as tiny specks moving on the paper.
Spider mite populations develop rapidly under hot, dry conditions, and plants under stress are particularly susceptible to injury. Spider mite problems can also be induced through the use of certain insecticides, such as Sevin, which destroy natural enemies of the spider mites.
Properly watering and fertilizing plants is a primary means of limiting spider mite injury. Forceful hosing of the plant foliage can be particularly useful because it can crush and dislodge many of the mites.
Insecticides that provide some mite control include Orthene, malathion and Diazinon. When heavy mite populations occur, it may be difficult to get control with any pesticide.
Soap sprays can be used to suppress mites on plants that are not injured by the soaps. Spray a small part of the plant, then check it in four to five days to test plant sensitivity to soaps. Such a treatment is best applied in early summer before mite populations get too large.