What is a primary benefit of using a mixture of herbicides?

Using a mixture of herbicides is beneficial primarily because it broadens the spectrum of control. This means that a combination of herbicides can target different types of weeds or plants simultaneously, making for a more effective weed management strategy. Additionally, mixing herbicides decreases the likelihood of resistance developing in target weed populations. When weeds are exposed to varied modes of action, they are less likely to adapt and survive, which helps maintain the long-term efficacy of the herbicides used.

In contrast, increasing costs, simplifying selection, or extending application effects are not primary motivations or benefits associated with herbicide mixtures. While these aspects may have some relevance, they do not address the critical need for effective and sustainable weed management solutions.