Iowa Commercial Pesticide Applicator Category 1A Questions and Answers (2024 / 2025) (Verified Answers)PDF

1. What is the greatest hazard when applying most herbicides? Answer Injury to non- target plants 2. Name some herbicides which are very effective against germinating weeds but less effective on established weeds. Answer Frontier, Lasso, and Dual 3. What soil conditions reduce the activity of many herbicides and require increased rates for adequate weed control? Answer Higher levels of soil organic matter or clay 4. Two herbicides which are more active on soils with a pH above 7.5 and can injure soybeans Answer Sencor and Lexone 5. Where are high pH soils most common in Iowa? Answer Next to limestone and gravel roads 6. Two herbicides that are more persistent and likely to carryover residues. Answer - Atrazine and chlorimuron 7. What factors can increase chances of herbicide carryover? Answer Dry weather, high rates, late application, and in the case of some herbicides, high soil pH