University of Missouri Extension

IPM1007, Revised November 2009

Practical Weed Science for the Field Scout: Corn and Soybean

Herbicide mode of action families

The purpose of this section is to assist diagnosis of herbicide injury and to categorize injury according to herbicide mode of action. There are many causes of abnormal crop response (injury), including weather, soil conditions (e.g., compaction), and other pests (diseases, nematodes, insects). It is important to recognize that symptoms typically associated with herbicide damage can also be confused with injury from other factors. Injury from herbicides can also increase when crops are under stress from other factors listed above. This section outlines crop damage due solely to herbicides and does not include damage due to other causes. Use the keys on pages 10 and 11 to identify the symptoms you observe in the field, and narrow down the choice to a specific mode of action family. Then compare the results you obtain by searching the key with the written descriptions and photographs shown in the following section. If in doubt about the cause of injury, your local University Extension specialists have access to digital technology and the services of the MU Extension Plant Diagnostic Clinic, (phone 573-882-3019) to assist with diagnosis.


IPM1007 Practical Weed Science for the Field Scout: Corn and Soybean | University of Missouri Extension

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