How to Identify, Control, and Prevent Brown Patch

Brown patch on lawn

In summer, your healthy lawn serves as the welcome mat for pool parties, barbecues, and Fourth of July celebrations, but brown patch can be a party pooper. How do you identify, control, and prevent brown patch? It’s easier than you think.

Whether you’re a beginner to lawn care or a seasoned expert, brown patch can happen to anyone. Here’s how to stop brown patch in its tracks to get your home lawn back to its gloriously green best.

What is Brown Patch?

“I kind of jokingly tell people when you wake up in the morning and go out, and all you hear is the hum of your neighbor’s air conditioning…that’s perfect brown patch weather,” says Dennis Patton. He’s the ornamentals, turf, and Extension master gardeners agent for the Kansas State Extension in Johnson County, where brown patch is a common headache.

“Brown patch can invade rapidly,” Patton says. “You can come home at 5 in the afternoon, walk through a perfectly green front lawn and wake up to brown patch taking hold.” That’s because a foliar disease, caused by the fungus Rhizoctonia solani, started coloring your grass blades with brown leaf spots while you were sleeping.

When brown patch thrives: Brown patch is a summer disease, and thrives in hot, humid weather. It survives the winter, dormant, in your lawn’s thatch. Then it turns active when dew periods exceed 10 hours and nighttime temperatures climb above 65. 

When you’ll see symptoms of brown patch: It depends on the type of grass you have: 

  • Cool-season grasses like tall fescue, perennial ryegrass, Kentucky bluegrass, and bentgrass usually start showing symptoms in late spring. 
  • Warm-season species like St. Augustinegrass, Zoysiagrass, Bermudagrass, and centipedegrass show symptoms twice during the year: early spring and late fall.

How to Identify Brown Patch

dead brown grass next to bright green grass
Photo Credit: pornpra / Canva Pro / License

Brown patches can form on your lawn for many reasons, but brown patch disease has a few tell-tale features.

  • A big brown circle: seeing these circular patches is the disease spreading from grass blade to grass blade. They turn brown and brittle and create the spots that give the brown patch its name.
  • Lesions: Most times, the entire blade of grass won’t be brown. Instead, there will be an abundance of brown and copper lesions.
  • Green center: Often, the center of the circle will recover, creating a donut-like pattern.
  • Smoke ring: The perimeter is a gray-white band called a “smoke ring.”
  • White mycelium: In the early morning on dew-covered turf, white mycelium can often be seen on and between grass leaves of the affected areas. White mycelium’s appearance is thin, white, and spider-web-like.
  • Rotted sheathes: tug on the often still green grass. If it separates easily, this is a tell-tale sign of brown patch.

It’s important to keep in mind that, like most diseases, you may not see all the symptoms. However, these should give you a good indication if your grass has succumbed to the frustrating fungus.

How to Control Brown Patch

Brown patch can lay dormant for quite some time before it makes an appearance on your lawn. But how do we get rid of this funky fungus?

Control Brown Patch Naturally

You’ve identified brown patch, and now you need it gone. Here are some ways to get rid of brown patch without using chemicals.

  • Aerate: Increasing air circulation in your lawn can sometimes dry out and cure your brown patch problem. If nothing else, it often causes the fungus to return to its dormant state.
  • Dethatch: Like aerating, dethatching will increase air movement and dry out the fungus, leading to dormancy or elimination altogether.
  • Change your lawn care practices: Brown patch thrives in warm, wet, fertile lawns. Reduce your watering and avoid excessive nitrogen fertilizer in high growth times. Avoid watering in the evenings, which increases the risk of fungal growth.
  • Increase drainage: Improper drainage increases moisture, making brown patch thrive. With good drainage, diseased lawns will dry out easier, reducing and even eliminating the problem.
  • Don’t mow: Mowing a diseased lawn is like coughing without covering your mouth. You’ll fling the disease everywhere, increasing the risk of infection in healthy areas.

Control Brown Patch Chemically

Chemical treatment is typically needed in severe cases or on high-value or high-resistant grasses. First and foremost, be sure to read the label. You want to be sure that you’re treating the right disease and applying it properly.

Clemson’s HGIC guide also provides a table of active fungicide ingredients and their effectiveness on brown patch fungus.

Consider using products with these active ingredients to help control brown patch in your lawn:

  • Pyraclostrobin in Pillar G Intrinsic Fungicide
  • Fluoxastrobin in Disarm 0.25
  • Azoxystrobin, both with and without Propiconazole

It’s a good idea to go ahead and pick up two different fungicides. Alternating which ones you use can help prevent a buildup of resistance to any certain fungicide.

To apply fungicide, follow these tips for the best results.

  • Follow directions: Read the label and apply as directed.
  • Dry or wet application: Pay particular attention to whether to apply them when grass blades are wet so the product will stick, or whether to apply a granular fungicide when dry and water it in. 
  • Calculate the amount needed: The first step is to gauge the size of your lawn to see how much you’ll need.
  • Spreader dial: Check the back of the package to see how much to use and what you should set your spreader’s dial to for best results. 
  • Start with the perimeter: Once the spreader is filled, first spread the fungicide around the perimeter of the lawn and then use rows to completely fill in the interior of the lawn the same way you would if you were walking behind your mower.

Regular applications every 14-28 days will make sure your lawn is free of fungus and stays looking healthy and green through the summer. Here are some regular application recommendations.

  • For liquid fungicides, check your sprayer: It’s important to have the appropriate type of sprayer and to calibrate it for the product you’re using, explains the Michigan State University Extension.
  • Adjust the sprayer nozzle: Adjust as needed for the best coverage and apply the fungicide in a sufficient volume of water to obtain thorough coverage, but not produce runoff. 
  • Avoid bad spraying practices: Spray at a sufficient height from the grass and in appropriate weather conditions to avoid drift, or the product flowing out to plants you’re not trying to treat. 
  • Be safe: Be sure to follow instructions on the label for that particular product when it comes to mixing, spraying, and personal protective equipment. 

When you have a spot of brown patch, there’s also the question when applying fungicide of whether to spot-treat or spray the whole lawn. That depends on several factors.

  • The size of the lawn.
  • If the homeowner is working to reduce chemical usage. Homeowners should look at places in their yard where brown patch has historically been a problem and start there. 
  • Look at some of those locations and how you target your sprays and applications and decide whether you need to treat the entire lawn. 

In any case, the best way to deal with brown patch is to get ahead of it. “The idea is to prevent the outbreak,” Patton said. Once you already see the damage, you’re working to prevent new outbreaks.

Pro Tip: Spraying fungicides with a light breeze, between 2 and 6 mph, is better than spraying during completely still conditions, the MSU Extension explains. That’s because even without wind, there can be updrafts and eddies that cause the fungicide to fall off target. A little wind will give consistent movement to allow you to adjust accordingly. 

Brown patch on grass
Photo Credit: Scot Nelson / Flickr / CC0 1.0

How to Prevent Brown Patch

One of the most important tips for preventing brown patch is to keep your lawn healthy and happy. Here are some more often used preventative measures to keep brown patch at bay.

Prevent Brown Patch Naturally

Grass types are affected by brown patch differently. Here are some additional lawn care tips that will help you prevent a brown patch outbreak naturally.

  • Introduce disease-resistant turfgrass: Research your grass type. If it’s not typically disease-resistant, consider adding a disease-resistant type to reduce the percentage of susceptible grass in your lawn.

Here are the species that are most and least resistant to brown patch:

  • Grass types that are resistant to brown patch: Kentucky-31 tall fescue
  • Grass types that are susceptible to brown patch: Bentgrasses, tall fescue, and perennial ryegrass. With high temperatures and high humidity, Kentucky bluegrass is also susceptible.

Note: Kentucky-31 may be resistant to brown patch, but other, turf-type tall fescue varieties are now more commonly recommended for home lawns.

  • Control Irrigation: Water in the early morning hours. This allows the grass to soak up the water, and then evaporation takes care of any excess moisture. Watering in the evening creates a warm damp climate ideal for funguses like brown patch. If your lawn doesn’t need moisture, don’t irrigate.
  • Fertilize smartly: Avoid high-nitrogen fertilization during times of high growth. For cool-season grasses, this is late spring or summer. For warm-season grasses, this is mid-to-late fall or early spring. Avoid fast-release forms of nitrogen fertilizer altogether.
  • Mow Regularly: Mow in the morning. Keep lawns mowed on a regular basis to the proper height for your grass species. Lower than optimum mowing height can increase disease risks.
  • Provide good drainage: For both surface and subsurface areas, be sure to use proper drainage techniques. Correct soil compaction with core aeration.
  • Use soil test kits: Test your soil and make recommended adjustments. Apply lime according to test recommendations. A pH less than 6.0 may increase the severity of the disease.
  • Utilize pest control: Whether you choose natural pest control or chemical, be sure to use it. Pests can eat grasses, damaging them and making them more susceptible to diseases.

Whether you choose to replace grass types that are susceptible to brown patch, change your irrigation schedule, or aerate the lawn for better drainage (or a combination of several of these techniques), you’ll be well on your way to controlling this frustrating fungus in your lawn.

Prevent Brown Patch Chemically

If you’re looking for a different, often more aggressive method of brown patch prevention, try a chemical fungicide. Here are a few tips: 

  • Don’t wait: Fungal diseases usually start in the summer, so treat your lawn with fungicide starting in the spring. 
  • Do some investigating: Not all fungicides are created equal. Some treat only certain pathogens, so make sure you’ve identified the fungus affecting your lawn before you head to the store. 
  • Fungicides can be expensive: Like most non-natural lawn care methods, they can be pricey, so expect a little sticker shock. 
  • Read the label: Read the labels to be sure it treats brown patch, and how the herbicide should be safely applied.
  • Fungicides won’t solve all your problems: If you’re already seeing brown spots in your grass, begin treatment plans instead of prevention methods.
  • Regular application: Although no method is guaranteed, regular application will increase your ability to prevent brown patch.
Normal Grass in Lawn
Normal Grass in a Lawn
Photo Credit: Shadowmeld Photography / Wikimedia Commons / CC BY-SA 4.0

FAQ About Brown Patch

What are Common Mistakes When Dealing With Brown Patch?

The biggest mistake is waiting too late to start getting a handle on a fungicide regimen. 

Homeowners may want to go ahead and get a preventive schedule of fungicide applications in place before the weather turns because it just takes one change in the weather and it’s too late. 

Normal fungicide only lasts about three to four weeks depending on the product, so your fungicide application schedule could stretch into July or even August. It won’t be just a one-and-done.

What are Other Common Summer Lawn Fungus Diseases?

Here are some of the more common lawn diseases:

Large Patch: Very similar to brown patch, caused by another strain of the Rhizoctonia solani fungus, the Clemson HGIC says. Affected grass will show the same symptoms — thinning patches of light brown grass. Symptoms will vary greatly depending on soil conditions and grass types.

Dollar spot: It is also caused by a fungal pathogen, presenting smaller brown spots.

Red thread: It thrives in cool, humid conditions such as the Pacific Northwest, mostly in nutrient-poor soils, according to a guide from manufacturer Scotts. You’ll know you’ve got it if you see thin red hairs or strands extending from the grass blades themselves.

Rust diseases: It appears as irregular light-green or yellow patches on the lawn, but looking closely will reveal orange-yellow rust spores on individual grass blades. Proper fertilization in the spring can help prevent it.

Summer patch: It usually appears between June and September, during periods of high humidity when daytime temperatures climb above 85, showing up in the form of irregular brown patches, rings, and crescent shapes.

How Long Does it Take for Brown Patch to Go Away?

It depends on the method. 

If you’re using a natural technique, it could go away as soon as the fungus has dried up and died, or it could last for years, laying in dormancy for the right conditions to reemerge.

If you choose a chemical method, the application of fungicide lasts about 14-28 days. Severe cases will likely need more than one application.

Fungus Freedom

Keeping your lawn free of diseases isn’t typically labor-intensive, but it does take a good deal of time. Being fungus-free requires you to stay vigilant, stay on top of your routine lawn care, and stay up to date on lawn care information.

Would you rather devote your weekends to family, hobbies, or your side-gig? You’re not alone. Millions of Americans reach out to professionals to keep them fungus free. In fact, there are quite a few local, experienced, highly rating professionals in your area. 

Whether you’re just looking at options or looking to hire a professional today, a free and easy quote is a simple click or call away.

Main Image Credit: Scot Nelson / Flickr / CC0 1.0

Derek Lacey

Derek Lacey

Formerly the agriculture writer for the Hendersonville Times-News, Derek Lacey’s articles have appeared in U.S. News & World Report, The Charlotte Observer, News & Observer, and The State. He has won 15 awards from the North Carolina Press Association and GateHouse Media, for pieces ranging from news features and investigative reporting to photography and multimedia projects.