What is Large Patch Disease and How to Identify It?

You’ve invested time, money, and effort into creating a beautiful lawn. Then one morning, you notice something alarming—circular patches of dead or dying grass that seem to appear almost overnight. What you’re likely seeing is Large Patch disease, one of the most damaging lawn diseases affecting warm-season grasses in the Southeast. 

For Atlanta homeowners with Zoysia, Bermuda, or St. Augustine grass, understanding this common fungal disease can mean the difference between a quick recovery and a completely devastated lawn.

What Exactly is Large Patch Disease?

Large Patch disease (sometimes called “Brown Patch” when it affects cool-season grasses) is a fungal infection caused by Rhizoctonia Solani. This soil-borne fungus attacks the base of grass plants and can spread rapidly under the right conditions. 

Unlike many lawn problems that affect just the grass blades, Large Patch attacks the stems where they meet the soil. This makes it particularly devastating, as it can kill entire sections of your lawn down to the roots.

Why Atlanta Lawns Are Especially Vulnerable

Georgia’s climate creates perfect conditions for Large Patch: 

• Humidity levels regularly above 70% in spring and fall 
• Temperature fluctuations during seasonal transitions 
• Extended periods of leaf wetness from dew, rainfall, and irrigation 
• High nitrogen applications before dormancy periods 
• Predominance of susceptible warm-season grasses like Zoysia 

One Yardsy customer in Smyrna told us, “I thought I was taking good care of my Zoysia lawn with regular watering and fertilizing, but I was actually creating perfect conditions for fungus without realizing it.”

7 Key Symptoms: How to Identify Large Patch

Large Patch has distinctive characteristics that help distinguish it from other lawn problems: 

• Circular patches ranging from 2 feet to 10+ feet in diameter 
• Yellow or orange borders around affected areas (often called a “smoke ring”) 
• Patches that expand outward over days or weeks 
• Gray or tan discoloration of infected grass blades 
• Easy removal of infected grass (pulls up with minimal effort) 
• Rotting at the base of grass stems where they enter the soil 
• Faster progression in shaded, poorly draining areas 

Skip’s Tip: The yellow/orange ‘smoke ring’ border is the most distinctive feature of Large Patch. If you see circular dead patches with this characteristic border, you’re almost certainly dealing with Large Patch fungus.

When to Look for Large Patch in Georgia

Unlike some lawn diseases that strike during summer, Large Patch has a specific seasonal pattern: 

• Primary infection period: Fall (September-November) when temperatures range between 65-75°F 
• Secondary activity: Spring (March-May) as grass transitions out of dormancy 
• Dormant period: Summer months when temperatures consistently exceed 85°F 
• Most visible damage: Often appears during spring green-up when healthy grass grows, but infected areas remain dormant 

This timing often surprises homeowners, who mistake spring symptoms for winter kill, when the infection occurred months earlier. 

Common Conditions That Trigger Large Patch

Certain lawn care practices and environmental factors can increase your risk: 

• Excessive irrigation, especially in the evenings when grass remains wet overnight 
• High nitrogen fertilizer applications in late summer or early fall 
• Poor drainage creating consistently damp conditions 
• Excessive thatch (more than 1/2 inch) that harbors fungal spores 
• Soil compaction limiting air circulation to roots 
• Heavy shade preventing morning dew from drying quickly 
• Improper mowing height stressing the grass 

An Atlanta customer shared, “My automatic irrigation system was set for 10 PM watering. After learning this was contributing to my Large Patch problem, I switched to early morning watering and saw immediate improvement.”

Why Ignoring Large Patch Could Destroy Your Lawn

Unlike some lawn issues that resolve themselves, Large Patch requires intervention: 

• It spreads exponentially under favorable conditions 
• Affected areas may not fully recover for 2-3 growing seasons 
• Severe infections can kill large sections of lawn completely 
• Damaged areas become prime real estate for weeds 
• Each cycle of infection makes future outbreaks more likely 
• Treatment becomes more difficult and expensive as spread continues 
• The Large Patch Treatment Plan

The Large Patch Treatment Plan

Effective management requires a multi-faceted approach:

Immediate Response (Active Infection)

• Apply fungicide with active ingredients like azoxystrobin, propiconazole, or flutolanil
• Reduce irrigation frequency while maintaining adequate moisture
• Avoid nitrogen fertilization until disease is controlled
• Improve drainage in affected areas
• Bag clippings when mowing infected areas to prevent spread

Prevention Strategy

• Apply preventative fungicide in early fall (September) when soil temperatures drop below 70°F
• Schedule a second application 28 days later for continued protection
• Switch irrigation to morning hours (4-8 AM) to allow grass to dry during the day
• Maintain proper mowing height (2-2.5 inches for Zoysia and Bermuda)
• Improve air circulation by thinning the surrounding vegetation
• Reduce thatch through regular aerification
• Test the soil and correct imbalances that may stress the grass

Skip’s Tip: The key to Large Patch control is prevention. Once you can visibly see the disease, you’re playing catch-up. Before symptoms appear, a preventative application in early fall is your best defense.

DIY vs. Professional Treatment: What to Consider

Homeowners often start with DIY approaches, but should understand the limitations:

DIY Challenges

• Proper timing is critical and easily misjudged
• Fungicide selection requires specific knowledge
• Correct application rates are essential
• Commercial-grade products are often unavailable to homeowners
• Underlying issues may go unaddressed

Professional Advantage

• Precision timing based on soil temperature monitoring
• Access to professional-grade fungicides
• Equipment calibrated for precise application
• Comprehensive approach addressing cultural practices
• Regular monitoring for early detection

A homeowner in Charlotte told us, “I tried treating Large Patch myself for two years with limited success. The professional treatment from Yardsy not only cleared the existing patches but prevented new ones from forming.”

The Financial Impact of Large Patch

Considering the costs helps put prevention in perspective:

• DIY treatment: $50-150 per application, typically requiring multiple treatments
• Professional treatment: $75-200 per application, often more effective with fewer applications needed
• Lawn renovation: $2-4 per square foot if severe damage requires resodding
• Property value impact: Up to 5-10% reduction with visibly damaged lawn

Preventative measures cost significantly less than remediation of severely damaged turf.

5 Most Common Questions About Large Patch

Worried about Large Patch in your lawn? Skip and the Yardsy team can assess your lawn for early signs of Large Patch and create a customized prevention or treatment plan. Our professional evaluation can identify risk factors and address issues before they lead to major damage. [Request Lawn Disease Assessment Button]

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Written by Jonathan Gillespie, Director of Agronomy at Yardsy, with over 25 years of experience diagnosing lawn diseases throughout the Southeast.

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