Which strategy can help combat herbicide resistance?

Utilizing herbicides with different sites-of-action is an effective strategy to combat herbicide resistance. When weeds are exposed to multiple modes of action, it reduces the likelihood that they will develop resistance to any single herbicide. This rotational approach disrupts the reproductive cycle of the weeds, making it more difficult for them to survive and propagate resistance traits.

In practice, this means combining herbicides that affect different biological processes within the target weeds, therefore decreasing the overall selection pressure on any one mode of action. This strategy not only improves the efficacy of weed control but also contributes to long-term sustainability in herbicide use.

While the other strategies may seem viable at first glance, they do not effectively mitigate the risk of resistance. Repeated use of the same herbicide can lead to an increase in resistant weed populations, and applying herbicides during rain can reduce their effectiveness or lead to runoff without addressing resistance. Avoiding all herbicides altogether is impractical for many management systems and does not provide a solution to managing existing weed populations.