Surprising research results on gray leaf spot on turf and a new annual bluegrass disease were discussed at the PACE Turfgrass Research Institute’s 10th Annual Turfgrass Research Seminar held April 7 in San Diego.
Dr. Frank Wong of the University of California addressed 145 turf managers in a presentation update on disease management. He said there were several areas in which his research yielded some unexpected results:
- The genetic diversity of gray leaf spot isolates from the western U.S. is much higher than had been expected, possibly indicating that the disease has either been introduced many different times, or that it has been present in the West longer than previously believed.
- Gray leaf spot resistance to QoI fungicides has been detected in the West, though it is not yet widespread.
- For optimal control of gray leaf spot, Wong saw the best results when planting resistant varieties of perennial ryegrass (such as the variety Paragon), as well as tank mixes of contact fungicides (such as chlorothalonil or mancozeb) with systemics.
- A new Rhizoctonia-like disease has been causing problems on annual bluegrass in the West recently. The symptoms are similar to those caused by yellow patch, but unlike yellow patch, this disease occurs during warm weather. Genetic analysis indicates that the disease may be caused by Waitea circinata, a fungus that is closely related to Rhizoctonia. In preliminary lab tests, it was controlled by some fungicides.
PACE Turfgrass Research Institute (PACE) is a membership organization that provides research, education and information services to the turf management community.
Findings, presentations and handouts from the seminar are available on the PACE Member Edition’s website. Non-members may sample the website through a free three-week trial membership available at www.paceturf.org.