Problem Identifier Unit Screen//v.w/ RR Template

Problem Identifier Unit Screen//v.w/ RR Template Mites

Problem
Leaves are stippled, yellowing, or bronzed. There may be webbing over flower buds, between leaves, or on the lower surfaces of the leaves. Fruit may be russeted. To determine if the tree is infested with certain species of mites, hold a sheet of white paper underneath an affected leaf and tap the leaf sharply. Minute green, red, or yellow specks the size of pepper grains will drop to the paper and begin to crawl around.

Analysis
Several species of mites, including the two-spotted spider mite (Tetranychus urticae) and the pear rust mite (Epitrimerus pyri), attack pears. Two-spotted spider mites, which cause leaf stippling and webbing, may be detected as described above. Pear rust mites, which cause fruit russeting and leaf stippling and bronzing, cannot be seen without the aid of a microscope or strong hand lens. These pests, related to spiders, cause damage by sucking plant sap. As a result of feeding, the green leaf pigment disappears, producing the stippled or bronzed appearance. Mites are active throughout the growing season, but are favored by hot, dry weather (70°F and up).

Solution
Spray infested trees with an insecticide containing malathion. Repeat the spray 2 more times at intervals of 7 to 10 days. After the leaves have dropped next fall, spray the tree with a lime sulfur solution and a dormant oil. Predatory mites, which prey on other mites, may be available for control. If you are not sure whether your trees are infested with pear rust mites, bring an infested fruit spur to your local County Extension Office (see County Extension Agents) for confirmation.

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