In humid climates, which cultural practice helps reduce powdery mildew on ornamentals?

• A. Overly dense planting and increased humidity.
• B. Ignore disease management and rely on routine fertilization.
• C. Improve air circulation, prune for spacing, avoid overhead watering, and select resistant varieties.
• D. Rely on constant fungicide applications only.

Answer: (C)

Powdery mildew in humid climates is promoted by still, saturated air and leaves that stay wet, so the most effective cultural approach is to reduce leaf wetness and improve air movement around the plants. Opening up the canopy through pruning and providing adequate spacing allows air to circulate, which helps leaves dry quickly and lowers the humidity that the fungus needs to infect. Avoiding overhead watering and instead using base or drip irrigation keeps foliage drier and less hospitable to the mildew. Choosing varieties that are resistant or less susceptible to powdery mildew also reduces the chance of infection, even when conditions are favorable for the disease.

The other options don’t address these environmental and cultural factors: overly dense planting increases humidity and leaf wetness; neglecting disease management leaves plants vulnerable; and relying only on fungicides ignores how environmental conditions drive disease and can lead to repeated chemical use without addressing the root cause.