Lawn turning brown

Asked June 24, 2014, 8:57 AM EDT

My lawn has developed large patches of brown or dying grass. I have owned my home for 3 years, and throughout this time the patches have been present but really seem to be getting progressively worse and worse. The grass is centipede as are most in the neighborhood. Many, if not most, of the other lawns seem to be similarly affected. I am not sure if it is Brown Patch or Large Patch fungus, Cinch Bugs or something entirely different. Hopefully you can diagnose the problem as well as offer some treatment before I lose my lawn. I have included some pics which I hope can provide some additional info. Thanks for your help.

Charleston County South Carolina

1 Response

Large patch is a new name for an old disease of warm-season turfgrasses. This disease was formerly called brown patch, the same disease that affects cool-season grasses during hot weather. Other than the fact that they affect different grasses, there are several important differences between brown patch and large patch that necessitated a name change: they occur at different times of the year, produce distinct symptoms, are caused by different strains of the fungus Rhizoctonia solani, and require very different control strategies.
Large patch appears in roughly circular patches that are yellow, tan, or straw-brown. The patches are initially 2 to 3 feet in diameter, but can expand in size rapidly up to 10 feet or more in diameter, hence the name “large patch”. Multiple patches may coalesce to encompass even larger areas of turf. When the disease is actively developing, the outer edge of the patches are often red, orange, or bronze in color. Close examination of individual plants reveals the presence of reddish-brown or gray lesions on the leaf sheaths.

Large patch begins to develop when soil temperatures decline to 70°F in the fall, but the symptoms do not necessarily appear at this time. The symptoms of large patch are most evident during periods of cool, wet weather in the fall and spring. In many cases, symptoms may not become evident until early spring when the warm season grasses are greening up.
Large patch is favored by excessive nitrogen in the fall and spring, poor soil drainage, over-irrigation, excessive thatch accumulations, and low mowing heights. Centipedegrass and seashore paspalum are most susceptible to large patch, followed by zoysiagrass, and then St. Augustinegrass. Bermudagrass, rarely affected by large patch, recovers very quickly when the disease does occur.
Fungicides are available for large patch control, but must be applied on a preventative basis. Applications should be initiated in the fall when soil temperatures decline to 70°F, regardless of when symptoms have appeared in the past. One or two well-timed applications provide season-long control of large patch in many situations. In severely affected sites, repeat applications should be made on 4 to 6 week intervals as long as soil temperatures are between 40°F and 70°F. Mapping of affected areas in the spring for spot-treatment in the fall can substantially reduce fungicide expenditures.