Lawn Fungus Identification Guide & Pictures + 6 Ways to Avoid Them

This post contains affiliate links. If you click and buy we may make a commission, at no additional charge to you. Please see our disclosure policy for more details.

No gardener would want an ugly looking lawn. Poor placement of plants and DIY decorations can always be resolved easily, but identifying, managing, and eradicating lawn fungus could be the worst nightmare. Keep reading to delve deeper on how to avoid such situations. 

What Causes the Lawn Health to Deteriorate?

Well-manicured lawns are always appealing to the eyes. After hours of hard work, when the lawn shows brown patches or yellow spots, most gardening enthusiasts will rush to irrigate and supplement the lawn. Hold on though, before trying to correct the defects seen using nutrients, understand why the lawn is suffering.

The most common reason for the poor health of lawns is fungal growth. When there is enough organic matter to feed on and the setting of the lawn is damp and dark, fungi flourishes. To support you in lawn fungus identification, this article has valuable information, hacks, and lawn fungus identification pictures.

Lawn Fungus Identification Guide

Here are 7 types of fungus that can assist DIY gardeners in lawn fungus identification. Be patient when you check for these symptoms, as misinterpretation is a common error.

Brown Patch

Caused by Rhizoctonia fungi, brown patches start small but are quick to spread. It is easy to identify a brown patch, as it looks like a large spot where the grass seems to be dry and dying. Most of the time, the inside of the patch appears lighter in color than the outside.

Seen in both cool-season and warm-season grasses, lawns are more prone to this fungi when the temperature hits 65F to 70F after sundown. The brown patch usually appears as a circle or close to one, often going up to 3ft in width. Since this situation goes out of hand rapidly, early detection and correction are crucial.

Avoiding overwatering and excess use of fertilizers is the recommended treatment for this fungal attack. Experts often suggest the use of appropriate fungicide, usually with fludioxonil, to get rid of brown patch.

How to Treat Brown Patch Lawn Disease?

Brown patch on the lawn is caused by a particular species of fungus known as Rhizoctonia. The impact of the fungus is such that the turf condition declines. It can be treated by using a fungicide. You need to avoid using fertilizers containing nitrogen. Of course, if the fungus starts developing resistance, you may need to rotate the type of fungicide that you are using. Also, your lawn needs to be maintained in the best manner possible, or there is the risk of the fungus resurfacing.

Pink Snow Mold

Microdochium nivale is the reason behind the pink snow mold in your lawn. Unlike what the name suggests, pink snow mold does not need snow to thrive nor does it appear pink for long durations.

Occurring in cool conditions, especially after the snow has thawed in spring, it causes the grass to turn matted and straw-like. At times, the fungi form a white or pink coating over the grass as well. Usually, pink snow mold shrinks on its own when the temperature climbs up.

If this becomes an annual problem for the lawn, using thiophanate-methyl fungicide before it snows is the solution. Other ways to regreen the lawn is by aerating the lawn and removing the leftover thatch after mowing.

How to Prevent Pink Snow Mold Disease?

Snow piling up on the lawn needs to be removed very quickly since it encourages the growth of the pink snow mold. Snow cover should not be allowed to develop. Snowdrifts can be reduced by using snow fences and wind barriers. Do not allow snow to compact with skis or other devices. Use a fungicide regularly for prevention. Take care to remove excess thatch that has accumulated on the lawn.

Gray Snow Mold

Credit: http://www.msuturfdiseases.net/

Gray snow mold occurs as a result of the growth of various Typhula fungi species. It is seen in lawns that remain constantly damp and cool. The lawn fungus identification here is the gray or straw-colored patches on the turf.

One can differentiate between pink and gray snow mold, by the greyish tint to the matted grass in the case of gray snow mold. The site of the fungal attack is usually six to twelve inches wide. Again, like in the case of pink snow mold, the fungi die out as the temperature increases.

Mowing and aerating the lawn is the best way to speed up the healing process here. In addition, raking out the leftover thatch and cutting the grass shorter than usual also helps in accelerating the healing.

How to Treat Snow Mold Disease?

Applying fungicide might not be helpful if there is already an infestation. If you wish to remove snow mold, mow the lawn regularly. Tall grass is a good breeding ground for snow mold; hence, you need to prevent it from growing. Apply the rake over the straw-colored circles so the soil dries out faster and the matted mold circles loosen. Of course, snow mold can go away on its own since it tends to die out as the temperatures increase and the months approach the summer.

Pythium Blight

When different members of the Pythium family spread in the lawn during the hottest months, the grass suffers from pythium blight. Also known as grease spot or cottony blight, orange spots with gray rings around them are the markers of the disease.

Generally inflicting the cool-season grass, Pythium blight develops fluffy masses similar to cobwebs on the lawn. The infection takes better hold as the humidity increases and makes the lawn unsightly.

Fighting pythium blight without renovating the entire lawn can be done by applying mefenoxam fungicide. As a preventive measure, this fungicide can be applied at periodic but regular intervals.

How to Treat and Prevent Pythium Lawn Disease?

For prevention, you must keep the lawn healthy and make it less amenable to disease. Fertilizer needs to be applied generously, and watering needs to be done occasionally (around once a week). This ensures that the grass blades do not retain moisture beyond nightfall. Aeration may also be undertaken to prevent thatch build-up. This would also keep the soil from draining poorly, and fungus build-up would be checked. All possible measures may be taken to remove any patches from the lawn where water might accumulate.

If an infection has already happened, treatment is best done at the stage where the lawn is still oily before it completely turns brown. Thatch may be removed to do away with traces of the fungus. In case you decide to mow or aerate the lawn during an infestation, you need to regularly clean the blades and tools to prevent further infection.

Necrotic Ring Spot

As a result of the growth of Ophiosphaerella korrae fungus, this is a severe condition that inflicts lawns in cooler and wetter months. Affecting the root system of the lawn, the infection starts by yellowing the grass and proceeds to reduce its thickness.

Especially harmful to the Kentucky bluegrass, the fungi survive on the dead organic matter and soil in the yard. This disease can be pinned down with the appearance of frog eye-like rings on the lawn. These rings range from three to fifteen inches in size based on severity and can even reach 3ft in some cases.

An ideal method of containing the damage by necrotic ring spots is by executing systematic and timely maintenance. If the condition warranted the use of fungicides, thiophanate-methyl or fenarimol-containing ones should be used. It is more effective when administered immediately after irrigation and when the soil temperature is around 60F to 70F.

Summer Patch

It occurs when Magnaporthe poae fungi invade the lawn. Summer patch, as suggested by the name, is a disease that peaks during summertime, but the fungus starts growing in early summer or late spring. Be warned as this infection mostly affects cool-season grass.

Easily identifiable with the initial appearance of dark wilted patches that develop into large and yellow-brownish colors with time, summer patch causes the grass to die from the tip. Once the damage is done, it is extremely difficult to correct it. Hence, prevention is essential in this case.

Summer patch can be prevented by not mowing away more than two-thirds of the length of the grass. Applying fungicide with propiconazole when the temperature reaches 65F is another preventive measure. Once the patches appear on the lawn, chemical treatments become ineffective and irrigation is the only way to save the turf.

How to Treat Summer Patch Lawn Disease?

Summer patch is primarily a condition of the root due to poorly draining soil. Some of the turfs may need to be pulled out in order to gauge the growth of the root and to understand how severe the infection is.

Dethatch the lawn. Provide water to the lawn in the early mornings while avoiding the evenings. The soil pH needs to be maintained between 6.0 and 6.5. Lawn fungicides such as Azoxystrobin or Propiconazole might be used. The fungicides may also be rotated to prevent the build-up of resistance. Of course, the application of fungicide might not be sufficient in itself. Proper care of the lawn also needs to be done. This would include mowing the grass at the correct height, correcting soil compaction and drainage, etc.

Red Thread

Credit: https://www.thespruce.com/

Occurring in conditions that are warm, moist, and abundant in nutrients, the fungus Laetisaria fuciformis causes this disease. While the fungi do not directly damage the lawn, it makes the grass more vulnerable to pestilence and other diseases. Especially found in soils that have low nitrogen levels, the red thread is extremely easy to spot

The lawn fungus identification can be done when a reddish hue is noticed in patches of grass. Later they seem to appear yellow or bleached and have a maximum diameter of two feet. As a matter of fact, this disease clears itself from the lawn on its own.

Chemically treating this fungal infection is not advised but in severe cases, application of fungicide containing strobilurins is suggested. Mostly fertilizing the soil with nitrogen and regular aeration should take care of the problem.

How to Treat Red Thread Disease?

This fungus usually emerges because of low sunlight and poor fertilization. You need to fertilize the lawn properly. An appropriate amount of nitrogen needs to be given to the lawn, although in light doses.

Fungicides can be used, although they might not be required if proper maintenance is done. To control for the sunlight, pruning of nearby trees, bush, and shrubs may be done. Lime can be applied to the soil to maintain a pH of 6.5 to 7. The lawn also needs to be dethatched. The soil, if compact, needs to be aerated so that the roots have better access to air and oxygen while the drainage is also improved. 

6 Ways To Avoid Lawn Fungus

Here are 6 effective measures to avoid the growth of fungus in your beloved lawn:

1. Water the lawn routinely

Grass flourishes when they receive a sufficient amount of water regularly. Overwatering or underwatering the lawn can result in a serious decline in its health. For the lawn to have lush green grass without any fungal attacks, the time of watering also matters.

As a matter of fact, early morning is the best time to hydrate the lawn. This way, there is ample time for the grass to dry. Since fungi thrive in damp and dark spots, it is crucial that the gardeners give enough time for the water to evaporate away. Remember, allowing the moisture to stay in all night long increases the chance of fungal attacks.

2. Make sure to regularly aerate the lawn

Aerating the lawn well can go a long way in ensuring its ability to fight against fungal attacks. By allowing nutrients, air, and water to penetrate through the small holes in the soil, the grass roots can easily grow better and deeper. Also, soil compaction can be avoided by aerating the lawn.

In the process of aeration, thatch and debris left in the lawn are removed. This further prevents the growth of fungi. Keep in mind, growing season is the ideal time to aerate the soil.

3. Use only sharp mowers

It is a known fact that mowing habits seriously affect the lawn’s health. Therefore, using a sharpened mower is of utmost importance. Using a blunt mower tear off the top of the grass instead of cutting, whereas ragged grass blades are more prone to fungal diseases.

Also, cutting away more than the necessary length from the grass blades causes stress to the grass and weakens it. In order to keep the lawn healthy and immune to fungal diseases, do not mow more than one-third of the length of the blade. This may result in more frequent mowing sessions but boosts the lawn health exponentially.

4. Maintaining a healthy soil pH

A healthy pH level of the soil is necessary for the lawn to thrive. Grass grows lush and green at a pH level that is slightly acidic. The perfect pH level changes according to the type of grass grown but generally, levels between 6 and 7 are ideal.

Highly acidic soil promotes the growth of weed, fungi, and moss, so mixing lime into the soil is suggested. If the soil is too basic, it can be countered by blending sulfur into the soil. Regularly check the pH levels to know how to aid the growth of the grass. Moreover, the right pH is crucial for the grass to absorb all the elements available to it.

5. Utilize fertilizers wisely

Check Latest Price on Amazon

If there is a lack of nutrients in the soil, the lawn will look starved. The clear signs of malnourishment are patchiness, browning, and fungal invasion. Hence, proper fertilization plays an important role in lawn maintenance. These fertilizers have a great ratio of nitrogen, phosphorus, and potassium to facilitate the healthy growth of grass.

Also, fertilizing the lawn in excess can directly hit the health of the grass. Even worse, too much nutrients cause the blades of the grass to develop rapidly. When this rapid growth occurs, the roots cannot keep up and the health of the lawn deteriorates.

6. Consider growing a different species of grass

If it comes to notice that regardless of the attempts made to raise a healthy lawn if the grass simply does not thrive, it might be time to consider growing a different species of grass. Although as different regions have different weather and soil conditions that suit certain types of grass, look for the species that can flourish in your locality.

Also, the blending of several varieties can prevent the total spread of disease in the lawn. Some varieties of grass are less immune to diseases than others, so a total renovation might bring your lawn back to life.


Even the best of lawns go through downtime occasionally. Proper lawn fungus identification and implementation of ways to remove them can go a long way in keeping the grass lush and green. This guide has been compiled to help those with a green thumb to raise a fungi-free lawn and the lawn fungus identification pictures included will help in recognizing and picking out the right action plan against the fungal invasion.

Being proactive and acting quickly at the signs of distress ensures good lawn health. Always remember to water the lawn right and apply fungicide in cases of fungal attacks for a healthy lawn, that can also be beautified by landscaping.

Leave a Comment