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How to Get Rid of Grass Fungus?

How to Get Rid of Grass Fungus?

Have you been finding it hard to stop those ugly, brown patches from ruining your beautiful lawn? This may be due to the growth of grass fungus and you are right to feel concerned.

Grass fungus is one of the biggest nightmares of every lawn owner. It can rapidly undo all the hard work and time you have spent creating the perfect lawn.

Once grass fungus infestation sets in, it quickly spread and can be quite difficult to control. For‌ ‌that‌ ‌reason,‌ ‌I ‌have‌ ‌put‌ ‌together‌ ‌this guide‌ ‌to‌ show you how to ‌get‌ ‌rid‌ ‌of‌ ‌grass‌ ‌fungus and prevent it from re-emerging.‌

What Causes Grass Fungus

Fungus is an active microorganism that can be found naturally on lawns. Some of them are quite harmless and contribute to the wellbeing and growth of your grass by supplying nutrients.

However, under the wrong conditions, these fungi can cause diseases that lead to the disruption to the growth of your grass. Some of the common causes of grass fungus I have noticed include:

  1. Choosing the wrong turfgrass for your lawn
  2. Poor weather conditions (especially high humidity and temperature)
  3. Drought
  4. Overwatering
  5. Improper mowing
  6. Overfertilization
  7. Using the wrong fertilizer
  8. Compacted soil

What Are the Different Types of Grass Fungus?

What Are the Different Types of Grass Fungus

Grass fungus is very specialized and targets different types of lawns at different times of the year, under specific conditions. Knowing the kind of grass you have and the weather conditions can help you narrow down the options.

The problem, however, is that you cannot identify a grass fungus infection until the disease has completely taken hold. So to get rid of grass fungus, you must first be able to identify the type of infection and how it works. 

Not all fungicides are the same and some are more effective than others for specific fungal diseases. Also, some fungal diseases can be corrected by simply changing your lawn care.

Here are examples of some of the common grass fungus, how to identify them, and the best methods to use to get rid of them.

Brown Patch

Brown patch is caused by a species of fungi called Rhizoctonia. It is a very common disease in cool-season grasses but may also occasionally affect some warm-season ones too.

The disease thrives in summertime evenings when the temperatures reach 65-70℉. The brown patch starts as a small, barely noticeable blot on the grass but can quickly rage out of control if it is not noticed or treated on time.

Brown patch, as the name implies, is characterized by roughly circular patches that can be as wide as 3 feet. The patches are usually darker on the outside than the inside.

Pythium Blight

Pythium blight (also called spot blight, cottony blight, or grease spot) is caused by different types of Pythium fungi like Pythium aphanidermaturm, Pythium ultimum, Phythium graminicola, among others. 

It typically affects cool-season grasses in the hot and humid summer months. It can also affect warm-season grasses, like bermudagrass, during rainy, cloudy, or humid weather all year long. 

A common trait of pythium blight is the 1-3 inch orange spots that appear on your lawn. On some early mornings, the outer circle of these spots will have light-gray rings. As the high humidity progresses, these spots slowly begin to grow cobweb-like clumps of mycelium.

Necrotic Ring Spot

Necrotic ring spot is caused by the fungus, Ophiosphaerella korrae. It is a severe fungal disease that affects a lot of grasses, but the Kentucky bluegrass is particularly susceptible. 

Necrotic ring spot thrives in the spring or fall when the months are cool and wet. Once your grass is infected, the fungus then feeds on the surrounding soil and dead leaves, killing the root system in the process.

A common symptom of this disease is that it causes the grass to fade to a yellow or light green color before it eventually thins out. You can tell that your grass is infected with necrotic ring spots when you notice 3-15 inch rings that look like frog eyes.

In some instances, these ring patches can grow as wide as 3 feet. When this happens, the grass begins to die.

Leaf Spot

Leaf spot can be caused by a wide variety of fungi, including Bipolaris sorokiniana. Although they affect a large range of grasses, bluegrass and Bernudagrass are particularly susceptible.

Once infected, the leaf spot will cause your grass to thin out and give it an unsightly appearance. Eventually, the grass will rot and die. 

An easy way to check for the presence of leaf spot is when you notice brown or purple spots on the blades of grasses. It can be easy to mistake this as a drought or insect issue. However, if left untreated, it enters the melting-out stage and kills your turf.

Rust Disease

Rust disease is a common grass fungus that causes your lawn to appear yellow or orange. It thrives well between spring and fall in temperatures between 68-86℉. It enjoys dampness but can also infect grasses in sunny weather, especially after prolonged humid weather.

Although the disease can hit any type of grass, the tall fescue, ryegrass, zoysiagrass, Kentucky bluegrass are all very susceptible.

How to Identify Grass Fungus on Your Lawn

  1. Pay close attention to any thin, irregular brown, yellow, or white patches that suddenly appear on your grass. These patches will make your grass appear frayed and sometimes, you can even see the soil underneath them.
  2. Be on the lookout for black, orange, gray, purple, or red spots on your grass as this can be a symptom of leaf spot. 
  3. Check if your grass has any black, gray, pink powder, or threadlike covering as this may indicate the presence of powdery mildew, pink patch, or red thread. 
  4. If your grass becomes wet, slimy, and dark for no reason, then you probably have a grease spot infection on your hands.

How to Get Rid of Grass Fungus

You can get rid of grass fungus using several methods. Some experts believe that boosting your soil or improving your lawn care routine to help get rid of the fungi naturally is the best option. 

While exploring more natural solutions to grass fungus infections, I particularly found this YouTube video helpful. Here you understand how boosting your soil and managing the heat and moisture proportions can help you maintain a lush turf.

Other steps you can take to get rid of grass fungus problems include:

  1. Try not to track the fungal spores from the infected area of your lawn to other areas. If you must walk through that part, I will advise that you wrap your footwear in plastic and remove it before stepping on uninfected grass.
  2. Grass fungus spreads rapidly, so if you mow the infected parts, try to catch all the clippings and dispose of them safely.
  3. You can also use natural remedies to deal with your fungus problem. Some options I like to experiment with include baking soda solutions, neem oil, and compost tea.

However, I should warn you that these natural remedies are most effective when fungal growth is fresh or in small quantities.

  1. However, if you don’t mind using chemical fungicides, I recommend watching this video to learn how to go about it so you can get the best results.

How to Prevent the Growth of Grass Fungus

  1. Only water your turf when necessary to prevent overwatering. Most lawns only need 1 inch of water each week.
  2. On the flip side, try not to leave your lawn to dry out or it becomes susceptible to infection.
  3. Only use slow-release, low-nitrogen fertilizers and follow the product instructions to prevent overfertilization.
  4. Mow your lawn often to keep the grass at a desirable height. However, try not to overdo it or you make your grass susceptible to fungal growth. Only mow ⅓ of the grass blades at any time.
  5. Aerate the soil at least once a year to prevent it from becoming compacted.
  6. Remove thatch layers greater than ½ inch to reduce the risk of waterlogging.


Once grass fungus grows on your lawn, it can cause a wide range of damage to your hard work ranging from bad aesthetics to grass death.  There are several diseases that can be caused by these fungi and they affect your lawn in different ways.

The best way to know what treatment to use is to determine the type of grass fungus plaguing your turf. To identify and choose the right remedy for your grass fungus issue, you should:

  • Closely observe your lawn to note the symptoms to figure out the disease present.
  • Use natural solutions that involve boosting the soil and managing heat and moisture conditions help you to get rid of grass fungus. You can also use organic and chemical fungicides to kill these fungi.
  • Regular maintenance will help prevent the onset of grass fungus.
  • Do not overwater, overfertilize, or mow your grass too much or it leaves it vulnerable to fungal infections.

If you have any further questions, please leave a comment behind and I will provide the answers you need.

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