What is Powdery Mildew? How To Treat Powdery Mildew On Grass?

Helen Skeates
Helen Skeates
15 min read

Powdery mildew on grass is a serious problem for all of us, so it’s important to know how to deal with it. An area you cultivated and looked after yourself would be a complete waste if it fell victim to disease.

Lawns are vulnerable to a wide range of pests and infestations since they are open spaces. If you’ve suddenly seen white powdery mounds in your grass, they could be mildew, which is a sort of mold.

To thrive, mildew need a specific climate. Because our outdoor patch is in such an ideal location, fungi like this one thrive and last longer.

Working in the garden is something that some people devote a lot of time to. Additionally, they take great pleasure in maintaining a well-kept lawn and garden. However, they may come across a white mold on the grass and wonder what it is. Powdery mildew, the white mold on the grass, is in fact a fungal disease.

While it won’t kill your plants on its own, it will put them under a lot of stress, which will eventually lead to their demise. So you need to know how to get rid of powdery mildew in order to keep your beautiful green space safe from any harm.

What is Powdery Mildew?

Powdery mildew on grass is a fungus, right? Your plants may be infected with this, which is a frequent illness. It’s still possible for this white fungus to appear on your lawn or garden plants, even if you take great care to keep them healthy.

Powdery Mildew On Grass - Causes & Treatment - LawnCARE

If you’ve read this far, you’ve probably heard of a fungal disease called Botrytis. It has the potential to appear just about anywhere. It appears, however, that warm, dry regions are suitable for this parasite. One must remember that this illness affects all plants. Vegetables (cucumber, watermelon, squash) and grapes, as well as flowers like lilacs and roses, are especially vulnerable in high-risk areas.

What causes powdery mildew in the grass?

In addition to dealing with the symptoms, you must identify the underlying factors that contribute to the spread of powdery mildew in your lawn.

Let’s begin with a discussion of the issue’s origins. Erysiphe graminis, a fungus that thrives by attaching itself to a living host, is the source of powdery mildew.

As long as the right conditions exist, this species of fungus may live and wait for the right time to appear. They accomplish this by letting their spores rest until the wind blows them to a suitable location.

The powdery mildew you observe on your lawn is the result of these fungus growing and producing asexual spores. While this fungus often adheres and reproduces on the leaf’s outer surface, it can begin an infection within two hours of spore contact.

This fungus has a preference for certain grasses, particularly turfgrasses, because of the environmental conditions. If you decide to replace your lawn with anything else, knowing about these types of plants will help you make an informed decision.

Additionally, powdery mildew can form when there is insufficient air circulation or an abnormally high level of water vapor in the atmosphere. A combination of low light intensity and moderate temperatures, around 60 to 70 degrees Fahrenheit, may also be to blame.

You should remove this fungus as soon as possible because it can become latent in order to survive, and it won’t go away on its own. That said, you might want to have a look at our piece on whether or not you should get mold testing done when purchasing a home.

What Are Key Symptoms?

It is time to learn how to properly identify powdery mildew on grass now that its definition has been clarified. As you learn more about powdery mildew signs, it becomes easier to identify it:

  • It’s easy to tell if your plants have powdery mildew since they appear to have been sprinkled with flour.
  • To begin with, you may have noticed that leaves have developed circular lesions. Occasionally, they can be seen on the stems and fruits of plants (in the case of plants).
  • Leaves and grass get yellow and dry after a while.
  • In the later stages of the disease, the fungus will cause the grass to twist, break, and become deformed.

Steps For Treating Powdery Mildew Infestation On Grass

Powdery mildew on grass comes from a specific fungus spore spreading and being catered in the grasses. If you’ve recently discovered them, you have three options for safely removing them:

Method #1. Replace the grass

To begin with, we’d like to recommend that you completely replace your lawn’s grass. There is a type of grass that is more likely to be affected by powdery mildew than others, and if that is the one you currently have, it may be time to choose a new one.

If your lawn has grown infested with mildew, whether it’s powdery white or another color, it’s highly recommended that you do this step. Whether or not your yard has been completely or significantly covered by mildew hordes is another consideration.

Method #2. Adjust the lawn environment

If your grass is not yet entirely infested with powdery mildew, another option is to make it impossible for the fungus that causes the infection to thrive on the lawn. This can be accomplished by removing the fungus’ preferred circumstances from your property.

Increase the air circulation in your grass by allowing it to breathe more freely. The fungus will have a harder time capturing water vapors in open lawns, which reduces their potential to trap water vapors in the vicinity.

In addition to allowing more sunlight into the lawn, trimming some of the surrounding trees and bushes will also help avoid fungal infection.

Method #3. Apply chemical treatment

The final step is to select a fungicide based on the mildew that is prevalent in your location, and then apply it to your crops. If you’re a novice, these may offer some health and safety problems for you and your neighbors.

Begin by getting permission from your neighbors, especially if you’re working on an area with a high number of residences nearby. It’s a good idea to seek the advice of an expert right away.

Using all three of these methods in succession on the same lawn will get rid of mildew the fastest. If you’re still having issues with mold in the yard, here’s a helpful article on how to remove it.

Powdery Mildew Organic Lawn Disease Control

How to prevent powdery mildew in the lawn

The best way to avoid powdery mildew in the future is to eliminate all sources of moisture in your yard.

  • Plant Kentucky bluegrass that is resistant to the mildew-inducing fungal disease as well as fine-leaved fescue in regions that are frequently shaded.
  • Conserve your yard’s light by cutting back landscape plants.
  • Keeping landscaping plants pruned and trimmed will help with air circulation.
  • Make sure you’re watering properly.
  • Make sure your grass gets the nutrients it needs by doing a soil test.
  • Check the space between young plants to make sure they don’t obstruct airflow or sunlight.

How does powdery mildew spread in the lawn?

In order to survive, powdery mildews need a living host, which is why they are called obligate parasites. Powdery mildew is unique among turfgrass diseases in that it survives the winter in active grass tissue rather than dead plant waste or thatch. When it’s springtime, the illness starts producing spores, which the wind carries to healthy grasses.

Can Powdery Mildew Go Away By Itself?

Not really. White dust on grass is caused by fungi that can thrive even in dormant windows. So basically once it appears, it won’t go away unless you treat it.

Top 5 Common Lawn Diseases To Watch For

1. Brown patch (Rhizoctonia solani)

Honestly, I’m not sure. White dust on grass is caused by fungi that can thrive even in dormant windows. So basically once it appears, it won’t go away unless you treat it.

2. Large patch (Rhizoctonia solani)

Honestly, it’s not that bad. They may survive even in the dormant winter glass, causing grass to be covered in white dust that can be seen in the grass itself. In other words, once it appears, it won’t go away unless you take steps to address it..

3. Pythium blight (Pythium aphanidermatum)

Pythium blight is a foliar disease that can swiftly spread through grass, especially seedlings, in areas that are vulnerable to the disease. Invasive pythium outbreaks are typically linked to poorly drained soils or moist, humid conditions in the turfgrass canopy that do not allow for adequate drying of the grass leaves. Pythium can thrive in newly sown regions that receive daily irrigation. Circles up to 3 inches in diameter, gray, water-soaked foliage and potentially white mycelium are all signs of Pythium blight. Fungicides (mefenoxam, etc.) are available for the control of pythium, but they must be used before to the onset of symptoms. Fungicides aren’t nearly as efficient in stopping the disease once symptoms start to show up.

4. Pink snow mold (Microdochium nivale)

This disease’s name, pink snow mold, might lead you to believe it’s easy to spot. Infecting turf does not require snow because pink snow mold only becomes pink for a short time. Pink snow mold can grow year-round in locations with mild, wet weather, such as the Pacific Northwest. Small circular areas with a water-soaked appearance around the edges are the first signs of a problem. In extremely damp conditions, the patch may show white mycelium with reddish pink edges. Dried-out spots turn brown and lose their color. Even though pink snow mold can be controlled if the signs are present, preventing the condition is far more successful. These two fungicides, DMI and strobilurin, offer the strongest potency and the longest residual control. As long as the conditions are favorable, many applications may be necessary.

5. Summer patch (Magnaporthe poae) or necrotic ring spot (Ophiosphaerella korrae)

Summer patch and necrotic ring spot in Kentucky bluegrass, while not as widespread as some of the other diseases mentioned thus far, can be one of the more challenging illnesses to control. Late in the summer, circular areas of tan or brownish turf are the most common symptoms. In the late spring and early summer, this disease begins its harm but the symptoms don’t appear until the turf is under stress later in the summer. Control options are extremely restricted as soon as symptoms appear. Summer patch and necrotic ring spot damage on turf can be prevented by using preventative fungicides. The pathogen is most active in the late spring, thus these treatments should be applied when the soil temperature reaches 65 degrees Fahrenheit. To get the best results, use a combination of strobilurins and propiconazole (DMI). After the first signs of illness appear, continuous watering can help the turf recover, but chemical management is futile.

Red Thread & Powdery Mildew: How To Prevent Yard Fungus - Allen Outdoor

FAQ about turfgrass disease

Will powdery mildew on grass go away?

A change in the environment will slow or halt the growth of powdery mildew. A gamble you take on how long that will take as well as the extent of your losses is all that matters. In addition, powdery mildew will return if the weather circumstances do.

When should I apply lime to my lawn?

Liming lawns is best done in the fall and spring. An additional benefit of the fall season is the precipitation, snow, and repeated freezing and thawing cycles, all of which aid in the breakdown of lime.

What other turf diseases can infect my lawn?

Many turfgrass diseases, including powdery mildew, can wreak havoc on your lawn if you’re not careful. The following turfgrass diseases can contaminate your lawn:


• Patch of dark brown hair

—The dollar spot

Ring of the fairies, if you will

—Snow mold in the form of a grayish-blue color

The leaf spot and the disappearance

Snow mold in the color of pink.

—Thread of red color


What if I can’t identify the fungus on my lawn?

Effective management of the fungus that has infected your grass requires accurate detection. Not all lawn diseases can be controlled using the same approaches that can treat one disease. Incorrect diagnosis can lead to incorrect therapy and worsening of the disease.

A local diagnostic lab or turfgrass pathology lab can assist in the identification of the fungus if that proves to be a challenge. Typically located at public colleges, these labs specialize in accurately diagnosing diseased grass.


When it comes to maintaining your lawn, powdery mildew on grass is just a small piece of the puzzle. It’s a big responsibility, so make sure you stick to our advice and keep your grass in flower.

Helen Skeates

Helen Skeates

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