Common ragweed (Ambrosia artemisiifolia L.) accessions in the Mid-Atlantic region resistant to ALS-, PPO-, and EPSPS-inhibiting herbicides
Date
2023
Authors
Journal Title
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Publisher
University of Delaware
Abstract
Common ragweed is a troublesome weed in many crops. Farmers and crop advisors in the coastal Mid-Atlantic region have reported inadequate control of common ragweed in soybean with glyphosate and herbicides with other modes of action. To determine if herbicide resistance was one of the causes in poor herbicide performance, seed was collected from twenty-nine sites where common ragweed plants survived herbicide applications and produced viable seeds. Common ragweed seedlings from those accessions were exposed to multiple rates of cloransulam, fomesafen, and glyphosate, applied as single postemergence (POST) herbicide application. All accessions except DE3 demonstrated resistance to one of the herbicides applied at a 2X rate, twenty-six accessions were 2-way resistant (glyphosate- and cloransulam-resistant) and 3-way resistance was present in eight accessions collected from three different states. In a separate study, select accessions were then treated PRE with ALS- or PPO- inhibiting herbicides. All accessions treated PRE with the ALS-inhibitors chlorimuron or cloransulam demonstrated resistance at the 2X rates. The accessions treated with the PPO-inhibitor sulfentrazone, had survivors at the 2X rate. When the same accessions were treated with fomesafen one had survivors at the 2X rate, and one had survivors at the 1X rate. Results from these tests confirmed common ragweed with 3-way resistance to POST herbicides is widespread in the region. In addition, this is the first confirmation that common ragweed accessions in the region are also resistant to ALS- or PPO- inhibiting herbicides when applied PRE.
Description
Keywords
Common ragweed, Herbicide, Postemergence, Preemergence, Resistant