---
title: "Brown Patch Fungus in St. Augustine Grass: A Central Florida Guide"
canonical: "https://provlawncare.com/blog/brown-patch-fungus-st-augustine-florida"
business: "ProV Lawn Care & Landscape"
type: "guide"
category: "Florida Tips"
author: "ProV Lawn Care & Landscape Team"
published: "2026-08-29"
phone: "+1-407-594-7622"
last_updated: "2026-08-29"
---

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# Brown Patch Fungus in St. Augustine Grass: A Central Florida Guide

Brown patch (large patch) fungus hits Central Florida St. Augustine lawns November through May. Learn the pull test, treatment, and prevention that works.

Brown patch, properly called large patch, is a cool-season lawn fungus (*Rhizoctonia solani*) that attacks St. Augustine grass from **November through May**, whenever temperatures sit below 80°F and the grass stays damp for long stretches. To get rid of it: confirm the disease with the two-minute pull test, switch to morning-only watering, apply a labeled fungicide to active patches plus a buffer around them, and let the lawn fill back in as growth resumes. Here's the complete playbook for Central Florida.

Every fall, right around the first stretch of cool nights, the same thing shows up across St. Cloud, Kissimmee, and Lake Nona: yellow circles blooming in lawns that looked perfect in September. If that's your yard, this guide walks you through confirming large patch, treating it without wasting money, and, just as important, the watering and fertilizing habits that decide whether it comes back next year.

## What is brown patch fungus, and why does it hit Florida lawns in fall?

Brown patch and large patch are two names for the same homeowner problem: a disease caused by the soil fungus *Rhizoctonia solani*. Turf scientists at the University of Florida's IFAS Extension (UF/IFAS) use **large patch** for the version that attacks warm-season grasses like ours, and that's the name you'll see on fungicide labels, but most Central Florida homeowners still call it brown patch. Either way, it's the region's signature cool-season lawn disease.

The fungus lives quietly in the soil and thatch all year. It wakes up when three conditions line up:

- **Cool temperatures.** Large patch is active when air temperatures run below 80°F, in Central Florida, roughly **November through May**. UF/IFAS notes it is essentially never seen in the summer months, so circles in July point to something else entirely (see our [summer brown-grass triage guide](https://provlawncare.com/blog/grass-turning-brown-florida-summer)).
- **Mild soil.** The pathogen is most aggressive when soil temperatures sit in the **65-75°F** range, exactly where Central Florida soils land in late fall and again in late winter.
- **Wet grass.** Long periods of leaf wetness are the trigger. Cool nights, morning dew, and an irrigation timer still running on its summer schedule create precisely the damp canopy the fungus needs.

It attacks all warm-season turfgrasses but is hardest on **St. Augustine and zoysia**: which covers the overwhelming majority of lawns around here, from Floratam St. Augustine in established neighborhoods to the zoysia going into newer builds.

## What does large patch look like?

The disease earns its name. Damage starts as roughly circular discolored patches **about a foot across**, which expand over weeks to **several feet in diameter**. As a patch develops:

- Grass turns **yellow first, then reddish-brown to straw colored** as leaves die.
- The **outer edge of the ring is the active zone**: it often looks darker, sometimes with an orange cast, where the fungus is currently feeding.
- Older patches can develop a **doughnut shape**: the center recovers and greens up while the ring keeps pushing outward.
- Patches show up first in the **dampest parts of the yard**: shady corners, low spots, poorly drained areas, and zones that get hit by irrigation overspray.

## The pull test: confirm large patch in two minutes

Before you buy anything, confirm the diagnosis. Large patch has a tell that drought, dormancy, and insects don't, and checking costs nothing:

1. Walk to the **edge of a patch**, where yellowing grass meets green.
2. Grab a few grass blades and **tug gently**.
3. With large patch, the leaves **slip off the stem with almost no resistance**, because the fungus rots the leaf base. Look closely: the bottom of a pulled leaf is **dark, soft, and slimy**, and it has a distinctly **rotted smell**.
4. Now tug in a healthy area for comparison, leaves should hold firm.

If blades resist pulling and the roots are anchored, you're probably looking at drought stress or normal winter color, not disease. If the grass lifts like loose carpet in hot sunny areas in summer, think chinch bugs instead.

## Brown patch, gray leaf spot, chinch bugs, or just winter color?

Cool-season browning gets misdiagnosed constantly, and treating the wrong problem wastes money. Here's how the usual suspects separate:

| Clue | Large patch (brown patch) | Gray leaf spot | Chinch bugs | Winter dormancy |
| --- | --- | --- | --- | --- |
| **Season** | Nov-May, below 80°F | Hot, wet summer | Late May-Sep | After the first real cold snaps |
| **Pattern** | Circles and rings, often in damp or shady spots | General thinning; gray-brown lesions on blades | Expanding patches at hot, sunny edges | Uniform across the whole lawn |
| **Blade test** | Leaves pull free easily; rotted, smelly base | Spots and lesions on the blade itself | Live bugs float up in a coffee-can flush | Blades intact, crown firm |
| **The fix** | Morning watering + labeled fungicide | Stop night watering | Targeted insecticide | Nothing, it greens up in spring |

One more reassurance: St. Augustine in Central Florida goes off-color in a cold winter without being sick. If the whole lawn faded evenly after a cold front, no rings, no rot, no smell, that's dormancy, and spring fixes it for free.

## How do I get rid of brown patch in St. Augustine grass?

Treatment is a sequence, and the order matters. Fungicide applied over bad watering habits is a subscription, not a cure.

1. **Fix the watering first, it's the biggest lever.** Water only in the **early morning** (UF/IFAS recommends between 2:00 and 8:00 a.m.) so blades dry quickly after sunrise. Never water in the evening during large patch season. And honor the seasonal cutback: most of Central Florida drops to **one watering day per week from the first Sunday of November**, which is genuinely all a cool-season St. Augustine lawn needs. Extra water in December is fungus food. Our [Central Florida watering days guide](https://provlawncare.com/blog/central-florida-watering-days-2026) has the full schedule.
2. **Mow diseased areas last, then rinse the mower.** *Rhizoctonia* can hitch a ride on wet clippings and equipment, so UF/IFAS advises cutting infected patches at the end of the route and washing the deck afterward before it touches healthy turf.
3. **Apply a labeled fungicide if patches are spreading.** Homeowner products built on **azoxystrobin, propiconazole, myclobutanil, or thiophanate-methyl** are the commonly recommended actives for large patch, sold as granules or hose-end sprays. Treat the visible patch **plus a buffer of a few feet of green grass around it**: the active edge extends beyond what you can see, and repeat exactly as the label directs. Always follow the label; it's the law and it's what makes the product work.
4. **Skip the nitrogen.** The instinct to "feed it back to health" backfires badly with large patch, readily available nitrogen during the disease window feeds the fungus more than the grass. Your last feeding of the year should be a **slow-release application in early October**, then nothing until spring. Our guide on [when to fertilize a Florida lawn](https://provlawncare.com/blog/when-fertilize-florida-lawn) lays out the calendar.
5. **Reduce the moisture load.** Chronic patches usually map to a micro-site problem: compacted or poorly drained soil, heavy thatch holding water at the crown, or a corner that never sees sun. Fixing drainage and airflow does more for next year than any spray does for this one.

## Should I apply a preventive fungicide in October?

If your lawn had large patch last year, there's a strong case for prevention, the fungus persists in the soil, so it almost always returns to **the same spots** when conditions come back. UF/IFAS is direct about this: fungicides for large patch work best **applied before symptoms appear**, because they stop the disease from spreading but can't bring back tissue that's already rotted.

The preventive window in Central Florida is **late October to early November**, as soil temperatures fall into that 65-75°F activity range. One well-timed preventive application on a lawn with a history, combined with morning-only watering, usually beats chasing expanding rings across the yard in January.

If your lawn has never had large patch, you likely don't need preventive fungicide at all. Good watering habits and a proper fall fertilization schedule are the real prevention.

## Will my grass grow back after brown patch?

Usually, yes, with patience. Large patch rots the **leaf bases**, but the stolons (runners) and roots frequently survive, especially when the disease is caught before rings merge into big dead zones.

The catch is timing. The disease is active precisely when St. Augustine has nearly stopped growing, so UF/IFAS warns that recovery **may be very slow**: damaged patches often look thin all winter no matter what you do. Real recovery arrives with **spring green-up in March and April**, when surviving runners start creeping back across the thin spots. Resist the urge to speed it up with fertilizer in January; that helps the fungus, not the lawn.

Give recovery a fair chance before replacing anything. If bare areas larger than a dinner plate still show no new runners by **mid-spring**, spot-sodding is the fix, spring is an excellent installation window here, and our guide to the [best time to lay sod in Florida](https://provlawncare.com/blog/best-time-to-lay-sod-in-florida) covers timing and establishment watering. Just fix the drainage and watering problem first, or the new [sod](https://provlawncare.com/services/sod-installation) inherits the old disease.

## How do we keep it from coming back?

Large patch prevention is mostly about denying the fungus its damp canopy from November through May:

- **Water in the early morning only**, year-round, never in the evening.
- **Respect the winter schedule.** One day a week after the first Sunday of November is enough; check your county or utility for your assigned day.
- **Make the season's final fertilization early October, slow-release**: no late-fall nitrogen.
- **Keep mowing right through the cool season**: St. Augustine at 3.5-4 inches with a sharp blade, on the slower winter cadence. Our [mowing frequency guide](https://provlawncare.com/blog/how-often-mow-florida-lawn) covers the seasonal rhythm.
- **Clear fallen leaves promptly.** Central Florida's leaf drop runs mid-October through November, and a mat of wet leaves is a fungus incubator.
- **Fix chronic wet spots**: drainage, compaction, irrigation overspray, in the corners where rings reappear every year.

## Frequently asked questions

### Is large patch the same as brown patch?

For a Florida homeowner, yes. Brown patch is the long-standing common name; large patch is the technically correct name UF/IFAS uses for the *Rhizoctonia* disease of warm-season grasses like St. Augustine and zoysia. Same fungus family, same treatment.

### Does brown patch go away on its own?

The season ends it, activity stops once temperatures hold above 80°F in late spring. But an untreated infection can keep expanding all winter, and rings that merge leave large dead areas that take far longer to fill in. Minor cases sometimes stall out when you correct the watering; spreading cases deserve a fungicide.

### Can I rake out the dead grass and reseed?

Raking out loose dead material is fine, but St. Augustine isn't established from seed, it comes back from surviving runners, plugs, or sod. Clear the debris, wait for spring green-up, and patch with plugs or sod only where nothing recovers.

### Can brown patch spread on mower equipment?

Yes, the fungus can move on wet clippings and mower decks. Mow infected areas last and rinse the deck afterward. If a crew maintains your lawn, it's a fair question to ask how they handle it.

### Why does it come back in the same spot every year?

Because the fungus never left. *Rhizoctonia* survives in the soil and thatch between seasons, and the spots that stay dampest, shade, low drainage, overspray, re-trigger it every fall. Fixing the micro-site breaks the cycle in a way fungicide alone can't.

## Get a second set of eyes on it

The hardest part of large patch is catching it early, by the time a ring is obvious from the porch, it's been active for weeks. A crew that walks your lawn every week notices the first discolored circle and the soggy corner that caused it. ProV Lawn Care & Landscape has served Central Florida since 2018 with the **same crew every visit**, transparent pricing, and no contracts, across St. Cloud, Kissimmee, Lake Nona, Southeast Orlando, and Apopka. If your lawn is showing rings and you'd rather have an honest diagnosis than a guess, [request a free estimate](https://provlawncare.com/get-estimate): we'll tell you straight whether it needs a treatment or just a better watering schedule.

## Related Guides

- [Why Is My Grass Turning Brown in Florida Summer? A Homeowner's Triage Guide](https://provlawncare.com/blog/grass-turning-brown-florida-summer)
- [Orange County Watering Days 2026: Central Florida Irrigation Rules](https://provlawncare.com/blog/central-florida-watering-days-2026)
- [When to Fertilize Your Florida Lawn: A Seasonal Guide](https://provlawncare.com/blog/when-fertilize-florida-lawn)

## About the Author

ProV Lawn Care & Landscape Team. Local, family-owned lawn care and landscaping company based in Saint Cloud, Florida, serving Central Florida since 2018. Services: https://provlawncare.com/services. Pricing: https://provlawncare.com/pricing.

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