Brown Patches on Lawn? Causes & Expert Lawn Treatment Tips

Brown Patch lawn disease is a common and widespread fungus that, like Dollar Spot, can infect a variety of common turfgrasses and cause brown patches on your lawn. Brown Patch thrives when hot weather and high humidity settle in during the summer months. Uncommon in arid regions such as Southern California and the Mountain States, Brown Patch is a problem for yard-lovers in every other part of the U.S.

Brown Patch lawn disease is a common and widespread problem caused by Rhizoctonia solani fungus. The disease can infect a variety of common turfgrasses, but the most susceptible grass species include perennial ryegrass, tall fescue and the bentgrasses.

Brown Patch can also become a problem to Kentucky bluegrasses in mid-to-late summer during extended periods of high temperature and humidity.

If you see spotting on your leaf blades—which can eventually bleed together to turn the entire leaf brown—suspect Brown Patch is invading your lawn.

More obvious signs to identify brown patch lawn fungus are circular areas of brown and dead grass surrounded by a narrow, dark ring. Patches are typically irregular and can be quite large, as this disease can spread fast.

This brown spotting can take on different appearances depending on the characteristics of the grass it infects. The following are signs of brown patch based on the type of grass you may have in your yard:

• Closely mown grasses: Any grass you should cut short, like some Zoysias, will show circular rings of brown patches and an expanding gray ring on the outer edge—most noticeable when the grass is damp, especially in the early morning hours.
• High-cut grasses: Grasses that are kept taller often exhibit circular or nearly circular brown areas, but without the visible details of gray exterior.
• Tall fescue: Tall fescue varieties often don't exhibit the characteristic circular patterns. Rather, the fungus will appear on scattered blades of grass, so that the whole lawn may seem a little “off,” with a tannish cast rather than the vibrant green you want to see.

Your yard can (and if you have it, most likely did) become infected during a period of cooler temperatures. The disease can take hold and develop well below 80 degrees Fahrenheit, but doesn’t spread and become apparent to the naked eye until temperatures and humidity levels rise. Dew, mist, or rain on leaf blades in these conditions can contribute to the rise of Brown Patch.

The fungus that causes Brown Patch lawn disease is present in many areas. Disease prevention is very difficult if the grass species is susceptible.

Proper watering in the morning to prevent wet grass at night may be of some, though limited, benefit. Proper mowing on a frequent basis to promote air movement and drying of the leaf blades may be of more benefit when preventing and battling Brown Patch.

More tips for treating brown patch:

• Use moderate amounts of nitrogen fertilizer.
• Fungicides can be effective if applied before the onset of the disease
• Don’t over- or under-fertilize your turf, as that can encourage Brown Patch.

TruGreen® certified specialists know exactly what your lawn needs and what changes you may need to make to achieve a lawn you’ll love. If you suspect your lawn is infected or you’re worried it may become so, give one of our specialists a call to set you up on a plan for a healthy lawn.

If you have more questions about brown patch lawn disease, give us a call today for more information. TruGreen can help you remedy that sad, brown lawn, and rebuild a healthy, green lawn you can enjoy day after day.