09/04/2026
Powdery mildew: nature’s way of putting your plants in ghost mode
Seeing leaves that look like someone dusted them with flour? You’re probably looking at powdery mildew—a group of fungal diseases that LOVE showing up late in the growing season.
What is it?
Powdery mildew is a fungus that grows primarily on the surface of leaves and stems, creating that telltale white or gray powdery coating.
Where does it come from?
The fungus survives on infected plant material and, depending on the species, can overwinter on plant debris or infected buds. Spores spread through the air and thrive when conditions are right—especially with warm days, cooler nights, higher humidity and poor air circulation.
Is it a problem?
It looks pretty dramatic, but on many established landscape plants, late-season powdery mildew is more ugly than deadly. It can reduce photosynthesis and stress heavily infected plants, but a little mildew at the end of summer usually isn't an emergency.
DO I NEED TO TREAT IT NOW?
Nope!. We’re at the end of the growing season, and those leaves will soon be dropping anyway. Treating now generally isn't worth chasing the fungus around with a spray bottle.
BUT—clean it up!
If you're cutting back infected plant material, collect and discard those cuttings instead of leaving them in the garden. Cleaning up infected debris can help reduce fungal material hanging around your landscape.
