What is Summer Patch?

Summer patch resembles drought-stressed grass, but this lawn disease needs more than water to cure it. In this article, we’ll cover what summer patch is and how you can stop this disease from destroying your lawn. 


How to Identify Summer Patch

Summer patch is a root-destroying lawn disease that causes round patches of discolored grass. Summer patch can occur through the summer when soil temperatures rise above 65 degrees. 

Symptoms of summer patch:

  • 1- to 2-inch circular patches form on your lawn
  • The patches grow bigger, forming a yellow or orange outer ring
  • Your grass appears yellow or orange
  • The roots of the infected grass turn dark brown or black and rot.  

What Causes Summer Patch?

Summer patch thrives in warm, humid conditions, but these four factors make your lawn vulnerable to this fungus:

1. Grass cut too short

Low-cut grass makes your lawn susceptible to summer patch and other diseases. If you cut your grass blades more than one-third of their length when mowing, you risk “scalping” your lawn. 

2. Thatch

Thatch is a tangled mass at the grass roots that makes it hard for the soil to get fresh air or sunlight. Thatch’s dark, moist conditions start to breed various types of fungi, one of which is Magnaporthe poae, which forms the disease summer patch.

3. Nitrogen fertilizer

Too much nitrogen fertilizer in your soil during the summer contributes to summer patch. Nitrogen fertilizer can burn and kill the grass. This partially dead grass makes the soil ripe for developing a pathogen like summer patch.

4. Overwatering your lawn

Too much water stresses your lawn, and the excess moisture can encourage the growth of summer patch.

What Grass Types are Most Susceptible to Summer Patch?

While numerous stress factors lead to summer patch, sometimes the grass itself can be the problem. Summer patch is most common in Kentucky bluegrass, annual bluegrass, and fine fescues.

Kentucky bluegrass and annual bluegrass are cool-season grasses. Planting them in warm regions makes them vulnerable to summer patch.

Fine fescues are adaptable to many climates. These soft grasses are drought-resistant. Despite their versatility, they are susceptible to summer patch.

How Can You Tell The Difference Between Summer Patch and Other Lawn Diseases?

Brown patch is very similar to summer patch and sometimes mistaken for it. Summer patch attacks the roots of the grass, while brown patch attacks the leaf blades. Treatments for each are very different. 

You need to determine if your yard is suffering from summer patch, brown patch or some other lawn disease before beginning a treatment plan. Below is a chart of some of the most common lawn diseases and the patterns they create on your grass.

Summer Patch Brown Patch  Dollar Spot Necrotic Ring Spot  
Develops a circular formation on your lawn that’s yellow or orange.Similar to summer patch but forms brown circular patches.Develops circles that look like drops of bleach on your lawn. Forms full ovals. 

If you can’t determine which pathogen is infecting your lawn, don’t resort to a spray and pray method. The wrong treatment won’t fix the disease and could make it worse. 

Instead, send a sample of your grass to your county extension office to have them determine what disease is present, so you’ll know how to treat it.

How to Get Rid of Summer Patch

Left untreated, summer patch disease can destroy the root system of your entire lawn. Here are a few ways to eliminate this lawn fungus.

  • Use a penetrant fungicide such as Fungo 50, Rubigan, or Cleary’s 3336
  • Limit foot traffic.
  • Adjust watering habits by watering deeply and infrequently. Watering three times a week for 20 minutes will give your lawn an inch of water per week, exactly what it needs.
  • Overseed your lawn with fungus-resistant grasses like perennial ryegrass, bentgrass, or tall fescue.

How to Prevent Summer Patch

Here are some ways to prevent summer patch from infecting your lawn:

  • Dethatch your lawn: Buildup around the grass roots prevents the soil from getting the air, water, and sunlight it needs, making conditions ripe for fungus growth. Dethatching will allow your grass to get the necessary nutrients to fight off summer patch.
  • Avoid overwatering your lawn: Disease loves darkness, heat, moisture, and lack of air. Water deeply but infrequently to prevent summer patch.
  • Don’t cut your grass too low: Short grass is vulnerable to diseases. Only cut off about a third of the height of your grass blades.
  • Take care of your lawn: Regular lawn care includes mowing, aerating, and fertilizing to make your grass strong enough to fight off disease.  

 FAQ About Summer Patch

1. Is summer patch more common in warmer climates?

Yes. Summer patch is much more common in regions with temperatures between 70 and 80 degrees.  

2. Can I just spray the area with a treatment to get rid of summer patch?

Yes. Spraying a proper fungicide two to three times over the course of 28 days should eliminate the summer patch. Then you can refill the missing or dead areas of grass with fungus-resistant grass seed.

3. Will fertilizing the lawn help get rid of summer patch?

No. In fact, adding a nitrogen-based fertilizer in the heat of summer will only encourage the summer patch to spread.

When you fertilize in September or October, use a phosphorus- and potassium-based fertilizer that will lower the pH level of your soil.

Not sure if your lawn is suffering from summer patch or another lawn disease? We can help you find a lawn care professional near you who can bring your grass back to life.

Main photo credit: Scot Nelson | Flickr | Public Domain

About Wikilawn

Wikilawn’s mission is to provide the best resources and information to help you enjoy your outdoor spaces the way you want. Whether you are a DIY, lawn-loving, gardening guru, or someone who wants help in picking a local lawn care professional, we can smooth your path to a beautiful backyard!

About Wikilawn

Wikilawn’s mission is to provide the best resources and information to help you enjoy your outdoor spaces the way you want. Whether you are a DIY, lawn-loving, gardening guru, or someone who wants help in picking a local lawn care professional, we can smooth your path to a beautiful backyard!