Which statement is true about wettable powders?

Wettable powders are solid formulations that require mixing with water to create a suspension. They do not dissolve instantly; instead, they become dispersed in the water when stirred or agitated. This action allows the active ingredients to spread evenly throughout the solution, which is essential for effective application.

The need for stirring or agitation ensures that the particles remain suspended and do not settle at the bottom of the container, which can happen if the mixture is left standing. This characteristic makes proper mixing crucial to achieving the desired concentration and efficacy when using wettable powders.

Regarding the other options, wettable powders do not dissolve instantly, so the first statement is inaccurate. They can be effective in a variety of spray systems, not limited to low-pressure ones, so that option does not hold true. Additionally, wettable powders can often be mixed with certain other formulations, depending on compatibility, so the last statement is also incorrect. This further emphasizes the importance of the stirring or agitating requirement for successful use of wettable powders.