When mixing two pesticides, what is the most likely reason for wettable powders to form lumps?

The formation of lumps when mixing wettable powders with other pesticides is most commonly due to incompatibility. Incompatibility can arise when the chemical composition of the two products does not blend well, leading to clumping or aggregation of the wettable powder. This is particularly significant because wettable powders rely on the proper dispersion in the mixing solution to function effectively.

When two incompatible products are mixed, the particles of the wettable powder can attract each other instead of dissolving uniformly, resulting in lumps. This can hinder the effectiveness of the pesticide application, as the lumps may not disperse evenly in the spray solution.

In contrast, excessive agitation might lead to incorporating air and does not typically cause lumping; low water temperature can affect solubility but isn't a primary cause for clumping of powders; and incorrect water pH can influence pesticide performance and stability, but it doesn't specifically lead to lump formation in the same manner as incompatibility does. Thus, recognizing incompatibility is crucial for achieving a successful pesticide mixture.