Lawn Fungus Identification & Treatment

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In your journey of maintaining lawn or garden, you are liable to encountering lawn fungus problems, especially if the weather conditions are humid. Treating lawn against fungus to protect the grass is critical, thereby, preventing discoloration and dead grass which can lead to bad spots.

How do lawn fungus form

Warm, wet conditions are most favorable for the growth of fungus in your lawn. So, not having sun up for some days along with rains can factor into lawn fungus formation. Hence, it is advised that you do a check if there have been frequent rains or cloudy days in your area.

Lawn fungus identification pictures

Some common lawn fungus identification pictures are shown below :

  • Brown patch
Host grass - bentgrass, bluegrasses, fescues, ryegrasses.

Symptoms - Roughly circular patches - mainly brown, tan, or yellow in color ranging from 6 inches to several feet in diameter. Affected leave remain upright.

Months with symptoms - May to september.

Control - Fungicides are effective for brown patch control that can be applied on a preventive or curative basis. However, it should be kept in mind that curative measures may not be effective during periods of high temperatures. Because, the cool-season grasses grow slowly which makes it unable to recover from the damage under these cold conditions. You should take a preventive fungicide program for tall fescue and creeping bentgrass when the conditions are favorable for disease development. To get the best results, preventative applications should be initiated in the late spring or early summer when night temperatures exceeds 60°F.

Source:NC State Extension Publications

  • Dollar spot

Host grass - All types.

Symptoms - Dollar spots appear as small spots, similar to the size of a dollar coin, light tan or bleached-white in color. Generally grass that are mowed at more than 0.5”, spots may appear in size up to 6” or more in diameter. The affected part generally remains upright and also appear to have white/light-tan lesions along with light reddish-brown margins. Short, fuzzy white mycelium is often seen on affected grass in the morning when the dew is present.

Months with symptoms - February to november.

Control - Preventive fungicide control is recommended.

Source:NC State Extension Publications

  • Grey leaf spot

gray spot lawn fungus identification Image Credit: &

Host grass - tall fescue, perennial ryegrass, and St. Augustinegrass.

Symptoms - Initially appears as round/oval, tan in color spots having a dark brown border.

Months with symptoms - July,August and September.

Control - Preventive method is recommended for gray leaf spot treatment.The treatment should be initiated during mid-June or early-July in most locations, repeating applications on a 14 to 21-day interval.

Source:NC State Extension Publications

  • Leaf spot

Host grass - bluegrass, bermuda grass.

Symptoms - Initially appear as small, brown/black spots/flecks on the grass leaves or sheaths.

Months with symptoms - March to June, September to November.

Control -  Both preventive or curative can be done.

Source:NC State Extension Publications

  • Pythium

Host grass - bentgrass, bluegrasses, fescues, ryegrasses.

Symptoms - For cool-season grass, Pythium first appears as small, sunken, circular patches up to 1 foot in diameter during hot/humid weather. For warm-season grass such as bermudagrass,Pythium appears as small black/purple spots expanding into larger irregular areas, during prolonged periods of humid, rainy/cloudy weather at anytime of the year.

Months with Symptoms - June to August.

Control - Preventive fungicide control is recommended.

Source:NC State Extension Publications

  • Red thread

Image Credit:

Host grass - Kentucky bluegrass, tall fescue, fine fescue, perennial ryegrass

Symptoms - Red thread develops in circular/irregular patches ranging 4 inches to 2 feet in diameter. Infected leaves among patches are tan or bleached-white in color.

Months with Symptoms - March to June, September to December.

Control - Any of the preventive or curative measures can e taken.

Source:NC State Extension Publications

  • Rust

Image source:

Host grass - Kentucky bluegrass, tall fescue, St. Augustinegrass, zoysiagrass.

Symptoms - Early symptoms include small, yellow flecks developing on leaves and stems. The flecks expand over time into raised pustules, yellow or orange in color, that rupture to release powdery masses of spores.

Months with Symptoms -  March to june,September to November.

Control - Curative or preventive method can be taken.

Source:NC State Extension Publications

  • Summer patch


Host grass - creeping bentgrass, annual bluegrass, Kentucky bluegrass, fine fescue.

Symptoms - Summer patch appear in circular patches/rings,typically measures from 6 inches to 3 feet in diameter. Grass within these patches are normally off-colored, prone to wilt or poorly grown.

Months with Symptoms - June to September.

Control -  Preventive measure is recommended.

Source:NC State Extension Publications

When and How to check for lawn fungus

Checking for fungus in dry weather is hard. The best time to check for fungus in the grass is early morning, with the settlement of early dew over the grass.

So, start early with your grass fungus; check when the sun is not high up in the sky. Look for places just under the top grass surface. Those are the most likely places of fungus formation in your lawns. If you are unsure about something, whether it is fungus or not, taking pictures is a good idea. Use the images to compare against a fungus chart or research the Internet.

The lawn fungus treatment

There are two aspects to fungal treatment; preventive and curative.

  1. Preventive treatment is to ensure you don't have fungus problems in the future. This procedure is a form of insurance against fungus in upcoming time.
  2. Curative treatment deals with terminating the fungus which has already made inroads into the lawn. It is more about the present than the future concerns.

What to use

There are numerous fungal treatment products (both preventive and curative) available in the market. Consult your local store before you make a choice. Refer the instructions on the product to know how to use.

Fungal treatment products come in both liquid and granular form. Granular products need spreading and then watering of ground for effective application. Liquids, on the other hand, can be paired with a power hose for applying over the grass.

Again, educate yourself about the product you are using, like its number of applications, lifetime and pet-safety to avoid possible accidents or confusions.

How to Do lawn fungus control

Required tools and chemicals

For this process of fungal treatment, we will need two things:

  • A spreader
  • Fungal treatment product

You can use a handheld spreader if working on a small lawn. Else, use a wheeled spreader which is more convenient than the handheld one. The Scotts Turf Builder is our pick from the lot.

For the fungal treatment product, you can consult your local store on the available options. We recommend the Bayer Advanced Fungus Control.

The procedure

  1. First, fill the bucket of the spreader with the product.
  2. Adjust the settings on the spreader based on your needs (preventive or curative). Refer the instructions of the spreader for appropriate settings.
  3. Then, apply the fungal treatment product all over the lawn with the help of the spreader.

Some pointers

  • Prevention is better than cure. It is always better to have a periodic check for lawn fungus and take preventive measures rather than investing in terminating fungus after facing the problem.
  • Check for lawn fungus in the early morning. The time is perfect for spotting fungus patches in the grass.
  • Use the right amount of the treating product. Utilizing the appropriate amount of the product is necessary for effective prevention or curing of the fungal problem in your lawn. Incorrect amounts will mean low effectiveness of the product against lawn fungus or product wastage with harmful residues.

We hope this short article gives you a basic idea on how to deal with lawn fungus problems in your lawn, be it in the form of preventive or curative treatment. In case of questions and comments, leave them below.

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