Most garden fungal problems trace back to the same root cause: too much moisture sitting where it shouldn't.
Recognizing Common Types
Powdery mildew shows up as a white, dusty coating on leaves, common in humid conditions with poor air circulation. Black spot appears as dark, roundish spots on leaves, especially on roses, often followed by yellowing and leaf drop. Rust produces orange or rust-colored pustules on leaf undersides.
Prevention Beats Treatment
Good airflow between plants, watering at the soil line instead of the leaves, and morning watering that lets foliage dry by evening all go a long way toward keeping fungal problems from taking hold in the first place. Spacing plants properly when planting pays off season after season.
Treating an Active Infection
Remove and dispose of infected leaves promptly, rather than composting them, since many fungal spores survive composting and can reinfect the garden. Copper or sulfur-based fungicides can help control an active outbreak, applied according to the product's label.
