Zoysia patch - photo by B. Fresenburg
Bob, our manager in Huntsville, AL, says that almost every zoysia lawn he’s seen is infected with Zoysia Patch. J.D. in Ft. Smith, AR, is also seeing patch disease in his zoysia lawns. Zoysia Patch, also called Brown Patch or Large Patch, is a fungal disease of the Rhizoctonia family. It actually infects the grass in the fall, is inactive in the winter, and then becomes most evident during spring green up in moist, mild conditions.
Symptoms are circular or irregular patches of brown or orange grass from several inches in diameter to several yards, depending on the severity. There may be a brighter orange color around the edges, signifying that the disease is still active. If infected in the fall, the grass may also be more susceptible to winter damage. The fungal disease may appear in the same place, year after year.
Zoysia patch kills the new grass shoots, leaving the area open for weed invasion. It does not kill stolons or roots. (Stolons are the above ground runners that make the grass spread.) As the weather heats up, the disease will become inactive, and the grass shoots will grow back, but the disease is still there.
Some things you can do:
Be very careful not to infect other areas while this disease is active. Bag your grass clippings. Do not aerate or dethatch during this time. Do not mow while wet.
Do not overwater. Water adequately, but not frequently. Improve your drainage if that’s an issue.
Mow as tall as possible. I know we’re always telling you to mow short, but zoysia patch disease seems worse on zoysia mowed under 1”.
Call us if you see symptoms. There are no over-the-counter fungicides that you can buy for zoysia patch – you must have a professional do it. Your lawn tech can determine if you need a fungicide application.
Rhizoctonia Large Patch Disease of Zoysiagrass & Bermudagrass - from University of Arkansas
Controlling Brown Patch on Warm-Season Turfgrasses in Home Lawns - Alabama Cooperative Extension