Black Patches on the Grass | Causes, and Solutions

black patches in grass

One morning while I was watering and trimming my home lawns, I noticed these black patches in the grass.

I assume this is the most common lawn disease that every gardener deals with. 

So I searched google for “ Why there are black patches in the grass of my lawn?” 

After some research, I found this paper on this topic. 

Black patches are a common problem in evergreen shrubs.

So, Why there are Black Patches on lawn grass?

Black patches on lawn grass develop due to fungal diseases such as leaf spots, Pythium blight, leaf smut, and slime mold. To get rid of this, you need lawn care management like watering, fertilizing, removing thatch, mowing, irrigation, aeration, and finally, apply fungicides.

Leaf smut commonly occurs on bluegrass, fine fescue, and perennial ryegrass. Whereas slime mold occurs in warm seasoned grass and rarely affects cold seasoned grass. 

There are other reasons your lawn may occur a black patch, such as high heat and humidity, excessive nitrogen, moisture, poor soil damage, too much thatch, and compacted soil. 

Symptoms Of Black Patches In Grass

During the warm season mostly in June – July black patches occur on the upper side of the lawn leaves. 

These black patches look unattractive and hamper the health and vigor of the lawn and weaken its structure. 

Ideal conditions for black patches are created in the warmer season with massive deluges combined with heat and humidity.

If you see black tints on your lawn, look closely you can see large patches up to 2.5 feet in diameter. 

This fungus is not parasitic so it won’t do any actual harm to your lawn grass, it will make your grass less photosynthesis efficient. 

Cooler than normal temperatures with high humidity create the ideal conditions for slime molds. 

There are common symptoms of black patches in the grass, such as-

  • Leaves will be visible with reddish-black to purplish-black spots. 
  • Mold-like masses will be seen on the grass.
  • Cob-web-like growth of fungi can be noticed during high humidity. 

If you see any of these symptoms, your lawn grass has most probably been attacked by slime mold. It needs immediate treatment otherwise all of the grasses can be affected.

Treatment Of Black Patches In Grass 

Black patches need immediate action to control the spread in the grass. The grass needs aid to maintain health and regain natural color. 

Before using a fungicide, lawn care management is important to avoid a broad range of fungal diseases.

Lawn care management includes watering, fertilizing, removing thatch, mowing, irrigation, aeration and finally applying fungicide. 


You need to avoid over-watering your lawn, particularly in the shaded area of dark patches. Overwatering can harm your lawn grass. 

Proper watering can maintain the good health of your lawn grass and regain its natural color.


Over applying fertilizer can lead to a harmful situation for your lawn grass. Similarly, a lack of fertilizer can make your lawn grass dull. 

If you apply proper fertilizer the growth of your lawn grass will be increased. To ensure good health of the grass you need to apply fertilizer in a proper quantity. 

Removing Thatch 

Dead organic materials are really beneficial for your lawn grass, but an excessive amount of them can be harmful. So while thatching you need to make sure you remove the excessive organic materials. 

Dethatching prevents waterlogs in the roots of your lawn grass. It ensures proper drainage and prevents black patches. 


Mowing the lawn grass ensures the good health of the grass. If you ensure mowing to the grass, it will be easy for you to maintain the grass. 


Proper irrigation will help you to maintain the proper health of the lawn grass. If you irrigate the grass on a regular basis black patches or other diseases will not be able to attack the grasses. 


Proper aeration will help the lawn grass to absorb water, nutrient, and oxygen. Proper aeration is important for the healthy growth of the grass. 

Prevention Of Black Patches In Grass 

If lawn care management does not work for black patches on your lawn, then you have to apply fungicides to kill the fungi and the spores. 

For applying fungicide you need to identify the exact fungus causing black patches in the grass. 

There are some effective fungicides like Daconil, Garden Safe, Spectracide, etc. You can use these to prevent black patches in the grass. 

Some Common Problem Of Lawn Grass 

Other than black patches there is some common problem that can be seen in lawn grass. Every gardener faces them at times. Such as- 

If your lawn grass has been attacked by Anthracnose, you will notice discolored patches of yellow to red. With time these patches will turn black. 

If you notice large patches of yellowish or brownish grass outlining with a dark ring then it is Brown Patch.

Dollar Spot has small patches of dead grass.  

Fairy Ring is consist of mushrooms or dead grass forming a circle.

If you notice a rusty orange powder coat on the grass then it is Lawn Rust.

Leaf Spot has a brown or black spot.   

Circles of grass covered in a pinkish-colored mold are Pink Snow Mold

If you see dark, irregularly shaped patches of greasy grass then your lawn grass has probably been attacked by Pythium Blight

A thread-like fungal structure that grows on the grass blades is Red Thread

Slime Mold has irregularly shaped patches of grey yellow dust. 

Brown, dead grass with circular patches of pink-grey mold is Snow Mold

Stripe Smut has thin yellow stripes. 

If there are patches of dead grass that form a circle or semicircle with a bronze color outline then that is Summer Patch

If you notice any of these, you need to treat your lawn grass properly. Otherwise, these can spread all over the lawn. 

Wrapping Up- Black Patches In Grass 

After the discussion now you know how to treat black patches in your lawn grass.

Black patches in the grass can be treated with proper care. If you are dealing with it, don’t worry with proper care you will be able to get rid of it 

If you take care of your lawn grass properly from the very beginning black patches or other fungi will not be able to harm your lawn grass. 

Watering the turf properly and fertilizing them will help you to grow them healthy. 

Happy Gardening! 

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