This email just was sent out via Golfdom's "Putting Down Roots" e-newsletter. Karl Danneberger, Ph.D., talks a little Yellow Patch:
The appearance of yellow to reddish brown rings is a common springtime occurrence on golf course turf. Yellow Patch, or cool temperature brown patch, is often associated with these rings. They occur on creeping bentgrass (Agrostis stolonifera) and perennial ryegrass (Lolium perenne), but the symptoms are most widespread on Poa annua. The patches can range from circular to irregular or scallop shaped, ranging from 1 to 3 feet in diameter. The yellow ring along the circumference of the patch ranges from one-half an inch to an inch in width. Yellow patch, caused by the pathogen Rhizoctonia cerealis , occurs under cool (50 to 65 F), wet, cloudy conditions. The disease is normally considered a minor problem, because with the arrival of warmer sunny conditions, the symptoms disappeared.
If daytime temperature increases (80s) and the yellow rings persist, the likelihood that brown ring patch is the culprit increases. The brown ring patch pathogen was initially described as "Rhizoctonia-like." Researchers at the University of California, Riverside identified the pathogen as Waitea circinata. Previously, researchers in Japan identified the same pathogen as causing similar symptoms on creeping bentgrass and named the disease "brown ring patch."
Fungicides are available for the control of brown ring patch and, should you decide to treat, contact your local extension specialist or company representative for recommendations.
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