Michigan cherries advice from MSU

Twospotted spider mite - Tetranychus urticae (Koch)

Twospotted spider mite

Twospotted spider mites (TSSM) have 2 distinct spots located on the front half of the dorsum behind the eyes. Males are much smaller than females, and have a distinctly pointed abdomen. Color can vary from pale yellow to green. The overwintering adults turn orange in September. TSSM can be found in the tree canopy from tight cluster through harvest. They typically construct webbing on the underside of leaves.

Monitoring and thresholds (ERM & TSSM): For summer populations of both mite species, examine leaves from several locations in the orchard using 50% spur leaves, 50% shoot leaves. Treat based on the following thresholds:

2-3 mites/leaf from petal fall to mid-June
5-7 mites/leaf from mid-June through July
10-15 mites/leaf in August

Presence of predaceous mites (>1/leaf) may justify delaying a treatment and repeating the cycle the following week.

Additional information

For more monitoring information and evaluation of available pesticides:
Michigan Fruit Management Guide
A Practical Guide to Scouting Apple Orchards – a DVD showing how to scout apple orchards.
MSU Diagnostic Services for assistance in pest identification.
MSU Fruit Crop Advisory Team Alert newsletters for current pest/crop conditions.

This information was developed from A Pocket Guide for IPM Scouting in Michigan Apples by David Epstein, Larry J. Gut and George W. Sundin. Purchase this in a pocket-sized guide for reference in the orchard from MSU Extension (publication E-2720).

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06/02/08