Herbicide and Nonherbicide Injury Symptoms on Spring Wheat and Barley

Knowledge of how herbicides kill weeds (herbicide mode of action) is helpful in selecting and applying herbicides to achieve effective weed control for a given situation. This understanding is also essential to preventing herbicide resistance. There are many herbicides available on the market, and these have several modes of action. Herbicides with similar chemical properties and activity are grouped into "families." An example of a herbicide family used in spring wheat and barley is the sulfonylureas of which tribenuron + thifensulfuron (Harmony Extra), tribenuron (Express), triasulfuron (Amber), metsulfuron (Ally), and chlorsulfuron (Glean) are members. Herbicides in the same chemical family generally have the same mode of action. Different herbicide families may or may not have the same mode of action. Therefore, understanding the herbicide's mode of action and the chemical family it belongs to will greatly aid in planning effective weed control and preventing herbicide resistance. An understanding of the different modes of action also is a helpful tool in diagnosing herbicide injury problems. The following pages describe characteristics of herbicide families commonly used in spring wheat and barley. They are grouped according to their mode of action: amino acid synthesis inhibitors, cell membrane disrupters, growth regulators, lipid inhibitors, photosynthesis inhibitors, seedling growth inhibitors, and unclassified.

Produced by Communication and Educational Technology Services, University of Minnesota Extension.

In accordance with the Americans with Disabilities Act, this material is available in alternative formats upon request. Please contact your University of Minnesota Extension office or the Extension Store at (800) 876-8636.

University of Minnesota Extension is committed to the policy that all persons shall have equal access to its programs, facilities, and employment without regard to race, color, creed, religion, national origin, sex, age, marital status, disability, public assistance status, veteran status, or sexual orientation.