This has been an interesting burndown season so far for a couple of reasons. First, the dry weather in late 2025 and early 2026 allowed many acres to be sprayed in January and early February. The number of acres treated during that period is truly impressive. Even better, most of those applications were very successful! Most weeds, including ryegrass, were controlled.

Another interesting outcome of these winter burndowns is that glyphosate controlled even glyphosate-resistant ryegrass (Picture 1). This was confusing until one recalled that research from 2011 indicated that glyphosate-resistant horseweed that was cold-acclimated did not sequester glyphosate in the cell vacuole, and this made the weed susceptible to glyphosate (Ge et al. 2011). This might explain why the applications in January and February were so effective against another winter annual weed, ryegrass.

More recently, in some Gibson County fields we visited, neither clethodim nor glyphosate controlled ryegrass (Picture 2). This aligns with recent ryegrass greenhouse screening we performed which indicated that some ryegrass populations are resistant to both clethodim and glyphosate.

Our research this spring at two Gibson County fields shows that tankmixes of Reviton (tiafenacil) or Sharpen (saflufenacil) with either glyphosate or clethodim consistently control ryegrass regardless of timing (Picture 3). These tank mixes are likely the most reliable option for burning down ryegrass as we progress into later spring.

Ge X, Ackerman, D, Duncan B, Spaur M, Sammons R. 2011. Glyphosate-resistant horseweed made sensitive to glyphosate: low-temperature suppression of glyphosate vacuolar sequestration revealed by 31PNMR. Pest Mgt Sci. 67:1215-21. Doi:10.1002/ps.2169.