Identification: Powdery Mildew appears as a white or light grey growth on the upper parts of grass leaves. This growth makes a lawn look almost as though someone had sprinkled flour on the turf. When affected by this disease, the leaves of the grass eventually turns yellow or brown and begin to shrivel and die. Lawns that are infected with this disease repeatedly or for long periods of time will have greatly reduced growth rates and, eventually, will die since even the grass that survives an infection will remain in a weakened condition for some time.
Cause: This disease is most likely to develop in areas that have dense shrubbery or trees that cause poor air circulation. Other contributing factors include areas with a lot of shade and areas with high amounts of humidity. The mildew favors temperatures in the range of 60-72 degrees.
- Water in the morning
- Reduce shade and improve air circulation where possible
- Aerate your lawn
- Make sure there is adequate drainage for excess water
- In areas with lots of shrubbery or trees, prune regularly to improve air circulation and sun penetration
- Plant grass/ground covers that are resistant to this disease
Treatment: Besides prevention, there are several fungicides available for treating an outbreak of Powdery Mildew. Fungicides that can be used to help control this disease include Acti-dione RZ, Banner, and Bayleton.
Grass Types Susceptible: Kentucky Bluegrass is especially prone to outbreaks of powdery mildew.