Cooperative Extension Area Integrated Pest Management Advisor Emily Symmes gave a scale management update recently at a walnut meeting in northern California. Symmes says it’s important for growers to assess how they are doing at managing the pest before making an application. Dead scale leave small caps on the trees and Symmes says it’s important for growers to pry those caps off with their fingernail or a blade. Living scale will have small, bright yellow bodies that are juicy under those caps.
Monitoring and Treatment Decisions
From UC IPM website: Start monitoring for walnut scale during the dormant season to determine the need for a treatment. Walnut scale monitoring can be combined with the monitoring of other pests as described in DORMANT MONITORING.If a treatment becomes necessary, make it during the delayed dormant period before shoot growth begins. If a high degree of parasitization is observed, treatments may be delayed until after crawlers emerge in late spring and oils, which are less disruptive to natural enemies, can be used. Put out double-sided sticky tape (in May) to monitor for crawler emergence. Read more from UC IPM.