Summer: Jun–SepTall fescueHumidity-drivenFungal (Rhizoctonia)

Brown Patch Disease in Nashville Lawns

If circular tan-brown patches appear in your lawn overnight in the heat of summer, it's almost certainly brown patch — the signature disease of Nashville's tall fescue. Our hot, humid nights are exactly what the fungus loves. Here's how to spot it, stop it, and recover.
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How to spot brown patch

Brown patch shows up fast — often overnight after a hot, muggy night. Look for:

  • Roughly circular brown/tan patches, from a few inches to several feet across, that seem to appear from nowhere.
  • A faint darker “smoke ring” around the edge in early morning while the grass is still wet.
  • Individual blades with tan, irregular lesions (often with a thin brown border) rather than the whole plant dying at the root.
  • It hits tall fescue hardest — Bermuda and Zoysia rarely get it badly here.

Not sure if it's disease, drought, or grubs? Brown patch is circular and appears in humid heat; drought stress is broader and follows sun/slope; grub damage pulls up like loose carpet. (Pests are a separate issue — watch for them too.)

Why Nashville fescue gets brown patch

The culprit is a fungus (Rhizoctonia) that explodes when nights stay above ~68°F, humidity is high, and the grass stays wet — a perfect description of a Middle Tennessee June through August.

Three things make it worse on Nashville lawns:

  • Too much spring/summer nitrogen — lush, fast growth is exactly what the fungus feeds on. This is the #1 mistake.
  • Evening watering — leaving blades wet overnight gives the fungus the moisture it needs.
  • Heavy clay + poor airflow — water sits, humidity lingers around the turf.

How to prevent it (the real fix)

Brown patch is far easier to prevent than cure, and the fixes are cultural, not chemical:

  • Water early morning, never evening — so blades dry by midday. Water deeply but infrequently.
  • Don't fertilize fescue in summer — hold the nitrogen until fall (see the Nashville fertilizing schedule).
  • Mow high (3.5–4″) with a sharp blade — taller grass and clean cuts resist disease; bag clippings while it's active.
  • Improve drainage and airflow — fall core aeration helps the clay drain.

Treating an active outbreak

Tighten up the cultural steps above first — they stop it spreading. If a valuable lawn is being overrun, a fungicide (look for azoxystrobin or propiconazole) will halt it; rotate products and follow the label. The good news: fescue usually recovers on its own as nights cool in September, and any thin spots are easily filled by fall aeration & overseeding.

🛒 Recommended gear

Brown-patch fungicides

For a serious outbreak — azoxystrobin / propiconazole lawn fungicides. Fix the watering and mowing first.

Spectracide Immunox Fungus Plus Insect Control for Lawns

Beginner friendly

Ready-to-spray hose-end; also controls listed insects

Myclobutanil 1.55%liquidcovers ~5,000 sq ft$15–$22 (32 oz ready-to-spray)
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BioAdvanced Fungus Control for Lawns (Primary Liquid Fungicide)

Beginner friendly

Propiconazole 2.42%liquidcovers ~5,000 sq ft$18–$24 (32 oz spray, covers 5,000 sq ft)
View on Amazon

As an Amazon Associate, Measure Lawn earns from qualifying purchases.

Frequently asked questions

What causes brown patch in Nashville lawns?

A fungus (Rhizoctonia) that thrives when summer nights stay warm and humid and the grass stays wet — typical of Middle Tennessee from June through August. It hits tall fescue hardest, and too much spring/summer nitrogen plus evening watering make it much worse.

How do I get rid of brown patch?

Start with culture, not chemicals: water only in early morning, stop fertilizing until fall, mow high with a sharp blade, and improve drainage. For a severe outbreak on a valued lawn, apply a lawn fungicide containing azoxystrobin or propiconazole per the label. Fescue usually recovers on its own once nights cool in September.

Will my lawn recover from brown patch?

Usually yes. Brown patch typically damages the leaf blades rather than killing the crown, so tall fescue greens back up as the weather cools. Any patches that stay thin are easily repaired by aerating and overseeding in the fall.

When does brown patch happen in Tennessee?

Summer — roughly June through September, peaking in the hottest, most humid stretches when nighttime temperatures stay above about 68°F. It can flare up within a single muggy night.

Does brown patch come back every year?

It can, because Nashville summers are reliably hot and humid. But lawns that are watered in the morning, mowed high, and not over-fertilized in summer get it far less. Prevention each year matters more than treatment.

Reseeding the damage this fall? Know your size

Measure your Nashville lawn free in ~2 minutes so you buy the right amount of fungicide, seed, and fertilizer — and can get accurate quotes.

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🧪 Nashville fertilizing schedule🔁 Fall aeration & overseeding🔍 Identify a lawn problem📍 Nashville lawn care guide🛰️ Measure your lawn free