An integrated vegetation management program is the best way to control unwanted weeds. But when herbicide resistance occurs, it can be a big problem. Here’s how to scout for herbicide resistance, what to do when you find it, and how to help prevent it from occurring in the future.
As defined by the Weed Science Society of America, herbicide resistance is “the inherited ability of a plant to survive and reproduce following exposure to a dose of an herbicide normally lethal to the wild type."1 In layman’s terms, it’s when a plant no longer dies from an herbicide.
Herbicide resistance can occur through basic evolutionary growth. Broadleaf weeds and grasses that have these naturally occurring gene mutations can survive herbicide applications. They are then able to seed, propagate and pass on this resistance to new plants. In a season or two, what might have started as a small complication can quickly turn into a big problem. And once weeds become resistant to herbicides, such as glyphosate-resistant kochia, it’s nearly impossible to manage them with chemical methods.
The simplest way to scout for herbicide resistance is to note what plants survive their herbicide applications. Weeds that are coming back season to season is the biggest indicator of herbicide resistance.
Preventing or eliminating herbicide-resistant weeds while also preserving all of the herbicide tools at your disposal is crucial to stopping their spread. A program approach utilizing both preemergence and postemergence herbicides is the best way to minimize the possibility that herbicide resistance will occur. Utilizing tank mixes of herbicides with different sites of action is also important to reduce the chance of a weed population becoming resistant. Be sure to use maximum labeled rates of herbicides in order to minimize the chances of resistance occurring.
Because resistance can be a natural part of evolutionary growth, it’s difficult to completely stop it from occurring. But measures like using herbicides with multiple modes of action or using tank mixes can reduce the risk of selecting for resistance. By scouting your application areas regularly and noting early when herbicide-resistant weeds are present, you can help prevent spread and eliminate issues before they grow out of hand.
Contact your Envu rep and view our product portfolio to learn more about herbicides with multiple modes of action and tank mixes for your integrated vegetation management program.
1Source: Weed Technology Volume 12, Issue 4 (October-December) 1998. p. 789.
