Herbicide and Nonherbicide Injury Symptoms on Spring Wheat and Barley

Understanding herbicide mode of action is necessary to diagnose small grains for herbicide injury, prepare herbicide mixes, and plan herbicide rotations to minimize development of chemical resistance. Herbicide mode of action is the sequence of events from the time the plant absorbs the herbicide until its death. Herbicide mode of action is a process that includes 1. plant contact, 2. absorption by plants, 3. movement within the plants to the site of action without being deactivated, and 4. reaching toxic levels at the site of action. Understanding how the herbicide works helps in determining the proper method and timing of application to maximize weed control and minimize potential crop injury.

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