Which pesticide formulations must be diluted before application?

The correct answer is based on the characteristics of the pesticide formulations mentioned. Wettable powders and emulsifiable concentrates typically need to be diluted with water or another appropriate solvent before application.

Wettable powders are solid pesticides that must disperse in water; they require mixing to maintain a uniform suspension and ensure even coverage. If applied directly without dilution, they would not effectively adhere to and treat the target surface. Emulsifiable concentrates, on the other hand, are formulated to mix with water to produce an emulsion. Diluting these pesticides is essential for achieving the desired concentration and effectiveness, as well as for enhancing safety during application.

The other options represent formulations that do not generally require dilution before use. Granules and liquids can be applied directly to the target area without the need for dilution, while solids and granules likewise do not require water for application. Fumigants and aerosols are designed for specific delivery methods that do not involve dilution, often relying on their own vaporization or aerosolization for efficacy.