Herbicide resistance is no longer something that is talked about as a possibility in the future. Glyphosate-resistant Palmer amaranth and resistance to ALS herbicides, such as Cadre, Classic, Pursuit and Strongarm, is now a reality for some growers.
Resistance, or the ability of a weed to survive a herbicide application to which the original population was susceptible, is determined through greenhouse studies of the weed’s seed.
Researchers will first determine if the weed’s presence is likely a result of failure to control it with herbicides because of environmental stresses, improper sprayer calibration, lack of spray coverage, incorrect herbicide use rate and failure to apply product in a timely manner when weeds are two inches or less.
Whether herbicide resistance has come to your fields or not, if you use herbicides, it should be your duty to use them properly to prevent future resistance issues.
To minimize the risk of weed resistance:
• Stay clean by using post-emergence herbicides. Base application timing on weed size, not crop growth.
• Make sure you are rotating herbicide chemistries, not just label names.