MDARD Michigan Core Pesticide Applicator Practice Exam

What enhances microbial pesticide degradation?

1. Pesticides are adsorbed to soil surfaces

2. Soils are cold and dry

3. Soils are warm and moist

4. Low levels of organic matter

The correct answer is: Soils are warm and moist

The process of microbial pesticide degradation is significantly influenced by environmental conditions, particularly temperature and moisture levels. Soils that are warm and moist create an ideal habitat for microbial activity. Microorganisms, such as bacteria and fungi, thrive in these conditions, leading to an increase in their metabolic rates and the ability to decompose organic materials, including pesticides. This enhanced microbial activity contributes to faster breakdown and detoxification of pesticides present in the soil, ultimately reducing their persistence and potential environmental impact. In contrast, when soils are cold and dry, microbial activity slows down, leading to reduced degradation rates. Additionally, low levels of organic matter can limit the nutrient availability for microbes, further inhibiting their activity. Pesticides being adsorbed to soil surfaces also tends to slow down degradation by restricting microbial access to the pesticide molecules. Thus, it is the combination of warmth and moisture that most effectively promotes microbial pesticide degradation.