What is That Powdery Mildew on Your Lawn?

No one wants to see any abnormalities on their home lawn. There are many alarming things that can appear in the grass, including powdery mildew. Powdery mildew is a common disease caused by a fungus, Erysiphe graminis. The disease mostly affects Kentucky bluegrass and fescue. The disease starts when spores are released by the fungus. The fungus spends the entire winter resting on plants, and releases the spores during the growing season. These spores get spread around by the rain and wind and infect grass blades.


When a grass blade gets infected, it gets covered by a white, powdery substance. This fungal coating can be removed with your fingers, but it will not stay away permanently. Some will mistake the disease for flour or lime. After a time, blades that have been infected can turn yellow, and eventually die. This will thin out a lawn and leave it looking splotchy.

High Concentration Periods

Powdery mildew seems to thrive in the spring and fall. This is because the temperatures are cooler, but humidity is still high. The disease likes the shade, and other spots where the air circulation isn’t good. Environment plays a big part in how well the disease spreads, so managing it is a key component for controlling the disease.

Disease Management

There are many things you can do to manage the environment to protect against powdery mildew, even in established lawns. For instance, keeping your trees and shrubs well pruned will keep light and heat shining on your lawn, and lessen the amount of dark spaces. If you’re planning a new landscaping job, then you should try to space out any plants and new shrubs. This will not only keep shade at a minimum, but it will allow for better air circulation. There are grass types that you can use that are tolerant of the shade.

You must regularly maintain the grass by watering, dethatching, and fertilizing. Make sure not to water too much, however. Overwatering can create an environment in which the mildew could flourish.

We all want to protect our lawns against disease and damage. By following these tips and knowing what to look for, you can be prepared to keep powdery mildew at bay.

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