How to Manage Pests
UC Pest Management Guidelines
Italian pear scale overwinters mostly as a mature scale. The cover is circular, about 0.06 inch (1.5 mm) in diameter, and light gray, but with a brown peak slightly off-center. Underneath the covering, the female's body is reddish, purple, or pink, a trait that helps distinguish the Italian pear scale from other armored scales found in walnut orchards. The scale is hidden under moss and lichens and cannot survive without this natural shelter.
This scale does not attack nuts, but feeds directly on the wood of the tree, affecting tree vigor and causing reduced fruit size. Light to moderate infestations do not seem to harm trees. Heavy scale aggregations may cause the bark to crack and can reduce tree vigor. Such large populations are seldom encountered, however, in orchards that are regularly treated for blight.
Look for Italian pear scale during the dormant period when you monitor other scale insects. Pay particular attention to scaffold limbs and branches that are covered with lichens. Scrape the lichens away to look for the gray scale covers and the pink scale bodies beneath. To monitor Italian pear scale with other pests, see DORMANT MONITORING. The key to managing Italian pear scales is to control the lichens. Regular blight treatments in spring will provide control of moss and lichens.
UC IPM Pest Management Guidelines: Walnut