Ornamental and Turf Pesticide Applicators Practice Exam

Which method is NOT recommended for managing powdery mildew on crapemyrtles?

1. Using resistant plant varieties

2. Applying fungicides at the first sign

3. Using a soil sterilant to kill the spores

4. Ensuring proper air circulation

The correct answer is: Using a soil sterilant to kill the spores

The method that is not recommended for managing powdery mildew on crapemyrtles is the use of a soil sterilant to kill the spores. This approach is ineffective for several reasons. Powdery mildew is primarily a foliar disease, meaning it affects the leaves of plants rather than the soil itself. The pathogens that cause powdery mildew typically overwinter on plant debris or infected tissues, rather than existing in the soil where a sterilant could impact them. Applying soil sterilants can also have detrimental effects on the environment and the health of the soil, disrupting beneficial organisms and potentially harming the plant itself. Rather than targeting the problem effectively, utilizing this method could lead to more significant issues within the ecosystem surrounding the plants. In contrast, the other options represent sound cultural and chemical practices for managing this disease. Using resistant plant varieties can minimize the incidence of powdery mildew altogether. Applying fungicides promptly at the first sign of the issue can help control its spread, and ensuring proper air circulation around the plants can reduce the humidity that powdery mildew thrives in, thereby preventing its development. Each of these methods enhances plant health and reduces disease pressure more appropriately than a soil sterilant would.