How to Manage Pests
UC Pest Management Guidelines
(Reviewed 12/07, updated 12/07)
Monitor during the dormant period to determine the need for a spring treatment to manage populations of walnut scale, frosted scale, European fruit lecanium scale, San Jose scale and European red mite.
How to monitor
Walnut scale: Natural enemies usually can be relied on to keep walnut scale from causing damage. If scales are present but a high degree of parasitization is observed, treatments will not be needed.
Frosted scale: If you find 5 or more nymphs per foot of last year's wood throughout the orchard and less than 90% parasitized nymphs, treatment is warranted.
European fruit lecanium scale: Same as frosted scale.
San Jose scale: If you find 5 or more black caps per foot of last years wood and less than 90% parasitism, treatment is warranted.
European red mite: No damage threshold levels are available to determine when to treat. Avoid treating low-to-moderate levels of European red mites because they can be important in maintaining predators of other mites.
UC IPM Pest Management Guidelines:
C. Pickel (Crop Team
Leader), UC IPM Program/UC Cooperative Extension, Sutter/Yuba counties