When the first group 1 (ACCase inhibitors) herbicide, diclofop (Hoelon), was introduced about four decades ago, wild oat control in cereals was the driver. Along with wild oat control came the benefit of excellent control of Italian ryegrass. Hoelon soon was registered in pulse crops at which point it could be sprayed on every crop in a 3-year winter wheat, spring cereal, spring pulse rotation.<\/p><\/div>\n<\/div>\n<\/div><\/div>\n
![\"Italian](\"http:\/\/smallgrains.wsu.edu\/weeders-of-the-west\/wp-content\/uploads\/sites\/2\/2020\/04\/HR-1-e1586367394443.jpg\")
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About 7 years after its introduction, Italian ryegrass populations were identified with resistance to Hoelon. Heavy selection pressure with continuous use contributed to resistant populations. Other Group 1 herbicides (e.g. Assure II, Poast, Puma, Discover, Achieve) and Group 2 (ALS inhibitors) herbicides followed (e.g. Amber, Osprey, PowerFlex). Over the past four decades, herbicides for Italian ryegrass control have come and gone. Some Italian ryegrass populations developed resistance in a few short years.<\/p><\/div>\n<\/div>\n<\/div><\/div>\n
The introduction of pyroxasulfone (Anthem Flex and Zidua) for use on wheat certainly was welcome relief after control of Italian ryegrass populations succumbed to several group 1 and 2 herbicides. Pyroxasulfone is a Group 15 (Very-long-chain fatty acid synthesis inhibitors) herbicide, like flufenacet (Axiom), but populations resistant to flufenacet are still controlled with pyroxasulfone. They have a similar mode of action<\/a> although the chemical families differ.<\/p><\/div>\n<\/div>\n<\/div><\/div>\n
![\"Herbicide](\"http:\/\/smallgrains.wsu.edu\/weeders-of-the-west\/wp-content\/uploads\/sites\/2\/2020\/04\/HR2.png\")
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