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Identifying Large Patch Disease on North Carolina Warm-Season Grasses and How to Protect Your Lawn

Just when fall hits and you think the danger of turf disease is over, lo and behold, here comes Large Patch disease. Suitably named, Large Patch can infect and spread in North Carolina lawns to a size of 10 feet or more. Homeowners become frustrated due to the discoloration of the grass. Untreated, it can lead to severe damage or ultimately kill the turf.

What is Large Patch Disease?

Large Patch disease is caused by a different strain of the fungus (Rhizoctonia solani) that also causes Brown Patch disease in cool season turf. It starts out as a small circular area, measuring 2-3 feet in diameter, and can rapidly spread from there.

 

Large Patch disease needs to meet the three factors that make up the “disease triangle.” These factors are:

 
  • Host (the susceptible species of grass)

  • Pathogen (the fungus, found in all soils)

  • Environment (factors such as overcast, cool, wet days)

Diagnosing Large Patch Disease in North Carolina

Large Patch appears in the late fall as the soil temperatures cool down below 70 degrees and there is  excessive moisture in the soil. It is particularly prevalent after periods of excessive rain with heavy cloud cover and little sunlight. The disease is common in coastal areas of North Carolina such as Wilmington, but it can also appear in areas farther inland, such as Raleigh.

 

In its different stages of growth, Large Patch disease retains a circular shape. In early stages, activity may cause blades to appear a bronze, orange, or red color. If the disease remains untreated, it will kill the grass blades, leaving large circular brown areas in the lawn.

 

Because the disease is active in the fall, as the turf transitions into dormancy, the symptoms may not be visible until the following spring as the grass starts to green up.  Recovery may take well into the growing season, depending upon the level of damage.

Types of Grass Affected by Large Patch Disease in North Carolina

It is common to find Large Patch disease on Centipede Grass, as this grass type is more susceptible to it than any other turf. You can also often find this turf disease on Zoysia, St. Augustine, and occasionally in Bermuda.

 

In Wilmington and the Coastal Plains, warm season grasses are common. Farther inland, for instance Raleigh, warms season grasses are still susceptible to Large Patch disease.

Proven Methods for Large Patch Disease Control

Mowing at the recommended height, limiting excessive fertilization and irrigation, are key steps to achieving Large Patch disease control.