A fungus disease can infect San Jose scale when weather conditions are suitable. Natural enemies do not seem to attack scales quickly enough to prevent scales from causing permanent damage to the trees. If twigs look unhealthy or are dead, examine them closely for the crusty scale. Examine twigs for scale during pruning operations. The small tent-style trap should be hung in a tree during the early pink bud stage.
Males usually begin to fly at bloom or petal-fall.
See North Central Regional Extension Publication 359, Insect Traps for Home Fruit Insect Control, for further information on where to buy traps. Once an infestation is detected, it is unlikely to go away and will probably continue to get worse if no action is taken. If an infestation is detected in its early stage, dormant pruning of infested wood can help control the problem. The first step in scale control is to apply a dormant oil spray in the spring before growth starts. Additional foliar sprays should be directed at crawlers of the second and third generations.