Plum rust mite or plum nursery mite, Michigan orchards

Integrated pest management resources for Michigan

IPM Scouting in Stone Fruits

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Plum rust mite or plum nursery mite - Aculus fockeui (Nalepa et Trouessart)

Plum rust mites (PRM) generally restrict their feeding to new foliage, causing these leaves to brown and roll upward longitudinally. Female PRM overwinter in dead or shrunken buds, moving to foliage as buds begin to open in spring. As many as 15 generations occur per year, with peak populations generally occurring in late July. Light to moderate populations are suppressed by predaceous mites.

Monitoring: Monitor new terminal growth for browning in July. PRM is mostly a problem where chemical spray programs have lowered populations of predator mites. PRM should be monitored after harvest in cherry to ensure that population levels do not reduce tree vigor for the winter.


“Firing” is caused by drought stress coupled with mite damage.	On plum, damaged leaves exhibit “chlorotic fleck,” a series of yellow spots 1-2 mm in diameter.

Additional information

For more monitoring information and evaluation of available pesticides:
Michigan Fruit Management Guide
MSU Diagnostic Services for assistance in pest identification.
MSU Fruit Crop Advisory Team Alert newsletters for current pest/crop conditions.
Cherry orchard floor management (pdf file) with implications for mite management.

This information was developed from A Pocket Guide for IPM Scouting in Stone Fruits by David Epstein, Larry J. Gut, Alan L. Jones and Kimberly Maxson-Stein. Purchase this in a pocket-sized guide for reference in the orchard from MSU Extension (publication E-2840).

The MSU IPM Program maintains this site as an access point to pest management information at MSU. The IPM Program is administered within the Department of Entomology, fueled by research from the Michigan Agricultural Experiment Station, delivered to citizens through MSU Extension, and proud to be a part of Project GREEEN.
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Updated 7/24/07