The Ohio State University

Home TurfNotes "Yellow Rings" are appearing again! Have received samples in the last several weeks, the first sample on April 24, and the pattern seems similar to previous years with the exception being this year symptoms started under slightly cooler conditions. The turfgrass affected is Poa annua and occurred on both push up greens and sand based constructed greens however more common on older greens. The symptoms are very similar to yellow patch. However, yellow patch occurs when temperatures are much lower. Temperatures in the mid 80s plus during the day often result in more dramatic symptom patterns. In past years the disease appeared to be wide spread around Memorial Day in the midwest. This is a rhizoctonia-like fungus and called Waitea circinata var circinata. The disease is called Waitea patch or brown ring patch. In Ohio the outer edge of the patch may turn brown but in many cases the predominate symptom pattern are yellow rings from several inches to over a foot in diameter.

Isolates from Ohio have been tested by the University of California Riverside, Dr. Frank Wong's lab, and verified as Waitea circinata var circinata. Isolate identity was confirmed using PCR-amplification and sequencing. In the past month or so, brown ring patch has been occurring in California and reported in the northeast.

Chemical control is still not completely understood and results of materials are somewhat variable. If Waitea Patch / Brown Ring Patch has already infected plants prior to an application, symptoms may linger or could reoccurrence. There are several fungicide trial reports available at Plant Disease Management Reports: 2009 volume, volume 3, click on Report by Section (left side tabs) and select turfgrass.

Posted by J. W. Rimelspach & M. J. Boehm