Black knot of plum, Michigan orchards

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IPM Scouting in Stone Fruits

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Black knot of plum - Apiosporina morbosa (Schwein.:Fr.) Arx

Black knot is common on plum and prune in the eastern U.S. and tart cherry in Ontario and western New York. It causes longitudinal swellings or corky outgrowths on shoots, spurs, bran-ches and trunks. Initially, knots are greenish and soft, later black and hard but often with new swell-ings developing at the ends. Limbs or entire trees may be killed from girdling as knots expand.

	Young (top) and older (bottom) black knots on plum.

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.

Images on this page provided by Alan L. Jones.

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