by Leslie Cox; Wednesday; August 22, 2018
What is it?
Powdery mildew is a fungal disease spread by spores. There are several different species of powdery mildew, and they are plant species specific. What attacks members in the squash family will not take hold on your beans or azalea nearby.
Powdery mildew is absolutely everywhere. The fungus lies dormant in the soil until conditions are right for the release of its spores.
What does it look like?
Powdery mildew appears as a few white or pale grey spots on plant leaves and generally spreads to encompass almost the entire leaf. It can spread to plant stems, flowers, and fruits. Thankfully, while it looks horribly unsightly, this disease rarely kills the plant…even when most of the plant is covered in white.
However, spreading powdery mildew can turn leaves prematurely yellow…eventually leading to them curling, turning brown, and then premature leaf drop. It can also precipitate early bud drop and impact on flower quality on flowering trees and shrubs.
How does it occur?
Warm days and cool nights combined with high humidity create perfect environments for the release of these fungal spores. They are spread by wind and splashing water drops. Best to irrigate with drip rather than overhead watering.
How to control?
Early detection is key, as it is with all other diseases and pests. There are a number of products on the market which work decently well on controlling the spread of the disease. However, none are wholly effective at eliminating the disease once it is established…although there have been decently successful results in reversing the growth of powdery mildew using potassium bicarbonate.
Steps to take to prevent
- Select plant types bred to resist powdery mildew
- Provide adequate air circulation
- Site plants where they will get at least 6 hours of sun daily
- Use a slow release fertilizer for a more controlled plant growth as new growth is susceptible fungal infection
For easy homemade recipes you can make up to control powdery mildew, click here.
