Which type of pesticide formulation requires a special emulsifier to mix effectively with oil?

Invert emulsions are a specific type of pesticide formulation that indeed require a special emulsifier for effective mixing with oil. Invert emulsions are prepared by mixing oil into water, as opposed to the more common emulsion where water is mixed into oil. This type of formulation is characterized by having a higher volume of oil compared to water. The use of a special emulsifier is crucial because it stabilizes this emulsion, allowing the oil and water components to blend properly and maintain stability over time. Thus, the effectiveness of an invert emulsion greatly depends on the emulsifier used.

In contrast, emulsifiable concentrates create a mixture that is predominantly water-soluble and often do not pose the same compatibility challenges as invert emulsions. Ready-to-use formulations are designed for immediate application without needing further mixing, and suspensions involve solid particles dispersed in a liquid, emphasizing a different aspect of formulation than emulsions.