By DoMyOwn staff
Powdery mildew is a fungal turf disease that thrives in heat and humidity, causing the lawn to have a grayish-white coating as the tiny spores coat the leaf surfaces or grass blades.
Does your lawn, shrubs or trees have areas that look like they’ve been dusted with flour? If so, you might be dealing with powdery mildew, a common turf and plant disease. Let’s take a closer look at what powdery mildew is, how to identify it, and what you can do to manage the disease.
Powdery mildew is a fungal turf disease that causes the lawn to have a grayish-white coating as the tiny spores coat the leaf surfaces or grass blades. It usually starts in small patches and can spread, especially in areas with high humidity and shade.
In shrubs, powdery mildew can cause yellowing and/or browning, leaf discoloration, premature leaf drop, and slower than normal growth. Plants in shaded areas are typically most affected.
Powdery mildew thrives when four growing conditions are met: high humidity, cool temperature, low light, and low air flow. It’s commonly found near buildings, under trees, or in areas with limited sunlight.
Periods of high humidity with cloudy skies create a great environment for powdery mildew to grow. Make sure to pay extra attention when this type of weather is expected. Now, how do we manage powdery mildew? Preventative fungicide treatments work best. Applying a fungicide before powdery mildew appears can stop the spread, but it won’t remove existing mildew. If the disease is already present, you want to focus on protecting new and unaffected grass or shrubs.
Let’s discuss some common active ingredients found in preventative fungicides. For foliar and ornamental treatments, Thiophanate-methyl is a great choice, but keep in mind this active ingredient is not labeled for use on lawns for this disease. For both lawns and ornamentals, Propiconazole and Myclobutanil are active ingredients labeled for powdery mildew. If powdery mildew is already thriving, higher rates and shorter retreatment intervals may be needed to stop the spread. Make sure to treat the currently affected turf and surrounding areas, especially in shaded areas, to protect against the spread of this disease. Make sure to follow the instructions on the product label for specific application rates.
Improving your lawn’s conditions can also prevent powdery mildew infestations. Increase sunlight exposure by trimming trees and overgrown plants. Pruning trees that cause a lot of lawn shade can go a long way. If you have dense shrubs, pruning them for better air circulation may help. Other ways to allow more air flow in lawns is by keeping a regular mowing schedule, dethatching in spring and fall when soil is moist, and turf is actively growing and by also removing unnecessary debris and dense landscaping features. If your lawn has persistently shady areas where powdery mildew returns every season, consider switching to a disease-resistant grass or shrub variety.
Check out our Powdery Mildew Treatment Guide on DoMyOwn.com for more tips and product recommendations! Thanks for watching! Don’t forget to like, comment, and subscribe for more lawn care and pest control videos like this one.
