Efficacy, crop response, and economics of alternatives to glyphosate for pre-plant weed control in small grains

Abstract

The value of glyphosate to growers practicing minimum or no-till farming has been primarily a function of three factors: broad-spectrum weed control, little to no carryover effect, and cost effectiveness. A 2-year field study was conducted in 2021 and 2022 at the University of Idaho Research and Extension Centers at Kimberly and Aberdeen, ID, to evaluate the efficacy of alternative pre-plant burndown herbicide treatments as compared to glyphosate treatment, the industry standard in small grain production systems. Herbicide cost comparison and crop injury observation were also conducted. Most herbicide treatments provided $\ge$90% control of the predominant weed species at 3 weeks after herbicide application. At least six different herbicide treatments had an equivalent cost to that of glyphosate at $26.50 ha⁻¹. No observable damage from herbicide treatments was observed and crop yield was not affected by the treatments. These factors indicate that there are alternatives to pre-plant burndown herbicides that are equally effective as glyphosate. With combinations of herbicides, each having a different site of action, weed control can be achieved while simultaneously reducing the risk of herbicide resistance.