In what situations are surfactants particularly beneficial?

Surfactants are particularly beneficial when applying herbicides on fluffy plant surfaces. This is because surfactants improve the wetting and spreading properties of the herbicide solution, allowing it to penetrate more effectively into the fine hairs or trichomes present on the surfaces of such plants. These fine structures can trap air and prevent herbicides from maintaining good contact with the leaf surface, significantly reducing the effectiveness of the application. By using surfactants, you enhance the ability of the herbicide to adhere to these challenging surfaces, increasing the likelihood of absorption and subsequent herbicidal activity.

In contrast, the other situations described do not provide similar benefits. For instance, using surfactants in dry conditions may not lead to optimal results because the lack of moisture can reduce the effectiveness of the entire herbicide application. Additionally, during high humidity days, the natural moisture in the air may already enhance the performance of herbicides without the need for added surfactants. Lastly, the use of surfactants is not relevant in the context of rodent control, as those applications do not typically involve the same mechanisms of absorption through plant surfaces that surfactants are designed to assist with in herbicide usage.