Iowa Pesticide Applicator Practice Exam

What typically indicates physical incompatibility in pesticide mixing?

1. Chemical reaction leading to gas production

2. Mixture remains stable

3. Formation of flakes or oily clumps

4. Pesticides easily combine into a new substance

The correct answer is: Formation of flakes or oily clumps

Physical incompatibility in pesticide mixing often manifests through the formation of flakes or oily clumps. When two or more pesticides do not mix well, signs such as separation, precipitate formation, or the presence of oily clumps indicate that the pesticides are not compatible with each other. This can occur due to differences in solubility, density, or other physical properties that prevent a homogeneous mixture. In contrast, a stable mixture would suggest that the pesticides are compatible, while chemical reactions typically involve changes in chemical structure rather than purely physical interactions. The ease of combining substances into a new form often implies compatibility, which contradicts the concept of physical incompatibility. Thus, the correct indication of physical incompatibility is the presence of flakes or oily clumps, signaling that the pesticides may not perform effectively when mixed.