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

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

Problem
The undersides of the leaves, the young branches, or the branch crotches, are covered with clusters of somewhat flattened white, yellowish, brown, reddish, or gray scaly bumps. The bumps can be scraped or picked off; the undersides are usually soft. Leaves may turn yellow and drop off, and branches may die back. The plant is killed when infestations are heavy.

Analysis
Many species of scales infest rhododendrons and azaleas throughout the country. Scales spend the winter on the trunk and twigs of the plant. They lay eggs in spring and in midsummer; the young scales, called crawlers, settle on the various parts of the shrub. The small (1/10 inch), soft-bodied young feed by inserting their mouthparts and sucking sap from the plant. The legs usually atrophy and a scaly or crusty shell develops over the body. The mature female scales lay their eggs underneath the shell. Leaf drop and twig dieback occur when scales completely cover the leaves and branches. An uncontrolled infestation may kill a plant after two or three seasons. For more information about scales, see Cottonycushion Scales, Wax Scales.

Solution
Spray with an insecticide containing acephate, diazinon, or malathion in midsummer (late spring in the South), when the young are active. The following early spring, before new growth begins, spray the branches and trunk with a dormant oil spray to control overwintering insects.

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