PACE Turf - Turfgrass Information Center

A New Disease of Annual Bluegrass, Ryegrass and Poa trivialis

Bottom line: A new disease of cool season turf was first diagnosed in California, in 1995 from Poa annua greens. Since that time, the disease has been observed in 7 different states, and in addition to Poa annua, it has caused serious damage to Poa trivialis and Lolium perenne (perennial ryegrass) used to overseed greens, tees, fairways and roughs. The disease, which is caused by an unusual, single-celled organism that grows inside the leaf cells of turf plants, has tentatively been identified as a chytridiomycete fungus. The frequency with which this disease occurs seems to have escalated in the past few years, causing severe yellowing and death of acres of overseeded turf, and increasingly severe damage to Poa annua greens. Because this disease has not been studied in the past, it’s management is an unsolved question, although the fungicide mancozeb appears to have at least ome ability to prevent widespread damage. And preliminary data from Clemson University suggests that products such as trifloxystrobin (Compass) and the yet to be registered product pyraclostrobin (Insignia) can actually control the disease curatively. A more comprehensive management program will be developed during the next ear, based on a collaboration between Clemson University and the PACE Turfgrass Research Institute.

The common name for this disease is rapid blight.

Printable version of full report PACE Insights Vol. 7 No.11

by Larry J. Stowell, Ph.D. and Wendy Gelernter, Ph.D.

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