You've waited all summer for the heat to break, the mornings to cool off, and your lawn to finally relax. Then you step outside one October morning and spot it: a big, ugly brown circle right in the middle of your yard. Did the dog do it? Did the mower leak? Nope. Odds are you're meeting large patch fungus, one of the most common fall lawn diseases across the South.
The good news? It looks far worse than it usually is, and there's plenty you can do about it.
Large patch is a fungal disease (caused by a soil-dwelling fungus called Rhizoctonia solani) that attacks warm-season grasses. If you have zoysia, it's the one you most need to watch for. Bermuda, St. Augustine, and centipede lawns can get it too.
The telltale sign is a roughly circular patch that can be anywhere from a couple of feet to 20 feet across. Patches often start tan or yellow, then fade to brown. Look closely at the outer edge and you may see an orange-ish or dark "smoky" ring, especially in the early morning when the grass is still damp. If you tug on an affected blade, it will often pull right off at the base, because the fungus rots the leaf sheath where the blade meets the stem.
Here's the part that surprises people: the fungus mostly attacks the leaves and sheaths, not the roots. That means your grass can often recover. It just takes patience, and some smart changes.
Large patch is a cool-weather disease with a very specific sweet spot. It gets active when soil temperatures settle into roughly the 50s and 60s and the weather turns damp. In Nashville, Charlotte, Greenville-Spartanburg, and Atlanta, that typically means October through November, and again in spring as lawns wake up. In the Dallas-Fort Worth area, the same window shows up a bit later in fall.
Why now? Your warm-season grass is slowing down as the days shorten. It's growing less, so it can't outgrow the damage. Add cool nights, heavy dew, and a few rainy stretches, and the fungus has exactly what it wants.
Then the grass goes dormant for winter, and those brown circles can sit there looking dreadful until spring. Many homeowners don't realize the damage started in the fall.
Large patch loves a stressed, soggy lawn. These are the usual culprits:
- Excess moisture. Watering in the evening, running sprinklers on a summer schedule in October, or poor drainage keeps the grass wet for hours.
- Thick thatch. A spongy layer of thatch holds moisture right at the base of the grass, which is exactly where the fungus lives.
- Compacted soil. Hard clay (hello, Atlanta and Charlotte) drains slowly and stresses roots.
- Shade and poor airflow. Spots under trees or along fences dry out slowly and tend to get hit first.
- A repeat visitor. The fungus survives in the soil and thatch, so patches often return in the same spots year after year.
You can't dry up the whole South, but you can tilt the odds in your favor.
Fix your watering. Water early in the morning so the lawn dries during the day, and cut back as temperatures drop. Most fall lawns need far less water than they did in July. If your irrigation system is still running on a summer schedule, it's time to adjust it.
See more: Watering Instructions (How Much To Water Your Lawn)
Keep the mower blades sharp. Dull blades tear grass and leave ragged wounds that fungus can slip into. If you've got an active patch, bag those clippings or mow it last so you don't spread the problem around the yard.
Don't let leaves pile up. A blanket of wet leaves is basically a fungus sleeping bag. Keep them raked so the turf can breathe.
Aerate and dethatch when the time is right. Core aeration in late spring or early summer, when warm-season grass is growing strongly, helps with drainage, compaction, and thatch buildup. It's one of the best long-term moves for lawns that get large patch year after year.
Consider a preventive fungicide. For lawns with a history of large patch, timing is everything. Preventive fungicide applications work best when put down in the fall as soil temperatures start dropping, before you see symptoms. Once the brown circles appear, a treatment can help stop the spread, but it won't magically turn the grass green again in the middle of winter.
In most cases, yes. Since the roots and crowns usually survive, healthy zoysia and Bermuda will fill back in once the weather warms and growth kicks in next spring. Spring is also a good time to feed the lawn, keep an eye on moisture, and give those recovering spots a little extra attention.
If a patch hasn't recovered by early summer, it may need a bit of patching with sod or plugs, but that's the exception rather than the rule.
Lawn problems can be tricky to diagnose. Brown patches can also come from grubs, chinch bugs, drought, dog spots, or simple dormancy, and each one needs a different fix. Treating the wrong problem wastes time and money.
That’s where Top Turf comes in. Our lawn care technicians know what fall disease pressure looks like in Nashville, Charlotte, Greenville-Spartanburg, Atlanta, and Dallas-Fort Worth, and our Lawn Fungus Program is built to stop it. We’ll identify what’s affecting your turf and apply targeted fungicide treatments to control active disease and protect against new outbreaks, so your grass heads into winter healthy and ready to rebound in spring. Our fungus program is separate from our Fertilization and Weed Control Program, so you can add it on to your current service or sign up on its own. We also offer core aeration to relieve the compaction that traps moisture and feeds fungus in the first place.
Spotted a mysterious brown circle in your yard? Reach out to your local Top Turf team and we'll help you figure out what's going on. Your lawn will thank you come spring.