MDARD Michigan Core Pesticide Applicator Practice Exam

How do wettable powders differ from soluble powders?

1. Wettable powders dissolve completely in water

2. Soluble powders must be mixed with water to apply

3. Wettable powders remain suspended while soluble powders form a solution

4. Soluble powders are used primarily for soil applications

The correct answer is: Wettable powders remain suspended while soluble powders form a solution

Wettable powders and soluble powders differ fundamentally in their behavior when mixed with water. Wettable powders contain active ingredients that do not dissolve completely in water. Instead, they disperse and remain suspended as fine particles in the water, which may require agitation to maintain an even mixture. This characteristic makes them suitable for applications where the active ingredient is meant to stay in a suspended state, allowing for better targeting of pests on surfaces. In contrast, soluble powders dissolve entirely in water, forming a clear solution that can be easily sprayed or applied. The ability of soluble powders to form a solution means that the active ingredient is fully available in the liquid, allowing for immediate uptake by the targeted pests or plants. The other options presented indicate misunderstandings about the characteristics of these formulations. For instance, some soluble powders can be mixed with water prior to application, but this does not specifically differentiate them from wettable powders in the context of how they behave when in contact with water. Similarly, while some soluble powders can indeed be used in soil applications, this is not a defining characteristic that differentiates them from wettable powders. The key distinction lies in the suspension versus solution behavior when combined with water.