Downy Mildew
Peronosporaceae
A disease of plants caused by oomycetes, or water molds. It appears as fuzzy or downy patches, typically on the undersides of leaves.
Symptoms
- Yellow to pale green spots on the upper surfaces of leaves.
- Gray or purplish downy growth on the undersides of leaves.
- Leaves may curl, wither, and die.
- Stunted plant growth.
Causes
- Cool, moist conditions with high humidity.
- Spores are spread by wind, rain, and contaminated tools.
- Infected plant debris left in the garden.
Prevention
- Ensure good air circulation and sunlight exposure.
- Avoid overhead watering, especially late in the day.
- Rotate crops and remove plant debris after harvest.
- Choose resistant cultivars when available.
Treatments
- Remove and destroy infected leaves or plants immediately.
- Apply copper-based fungicides or other appropriate fungicides.
- Improve air flow around plants.