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Solving a Moldy Mystery of Turfgrass Decline in the Pacific Northwest

Posted by struscott | September 10, 2011

In early 2010, Sara Paz, then grounds maintenance manager at Pacific Lutheran University in Tacoma, learned that the baseball and softball teams’ grass infield was looking weak and off-color—two weeks away from the beginning of season play. Usually covered by a tarp for several days at a time with a break for light and air, the grass field appeared to have fertilizer burn, only no fertilizer had been applied. PLU’s golf course gardener, more knowledgeable about turfgrass problems, told Paz a disease had damaged the field. Paz consulted the Washington State University Plant Diagnostic Clinic and Dr. Gwen Stahnke in Puyallup for answers and advice.
“I talked with her, got the procedure of how to take samples, and took them right down to the lab, plus I sent pictures of the affected area so they could look for patterns or margins,” Paz said. “They sent me an answer within 48 hours of what I was dealing with.”

WSU Extension Turfgrass Specialist Gwen Stahnke

The culprit was Pythium, and PLU was not the only place battling the familiar water mold with an elegant name. Two years ago, yellow, orange, and bronze circular patches began mysteriously marring the emerald-green turf of numerous putting greens on golf courses in western Washington, Oregon, and British Columbia. All told, the courses lost $500,000 in grass and greens from Everett, Washington, to Portland, Oregon. PLU turf managers treated their Pythium-infected baseball infield with a fungicide first, seeded the damaged portions, then finally replaced the entire area with new grass sod to have a playable field for the remainder of the baseball season, spending $7,500 in total.
In PLU’s case, poor drainage in the infield combined with sunny, cold days in January caused the turf to heat up under the tarp and condensation to collect, creating the perfect incubator for Pythium. Elsewhere, higher-than-average precipitation gave the mold the extra moisture it needed to flourish. But determining which Pythium species was responsible for the turfgrass degradation in such a large geographic area would be a challenge.

WSU Turfgrass Science Graduate Student Nathan Stacey

“The presence of Pythium hasn’t really changed; it exists in the soil in some unknown quantity,” said WSU turfgrass science graduate student Nathan Stacey. “From a diagnostic perspective, Pythium spores in samples would indicate Pythium activity. The problem is that there are more than 150 Pythium species. We’re trying to isolate the species of Pythium that caused the decline in turfgrass.”
Last October, the WSU Puyallup Research and Extension Center, Northwest Turfgrass Association, and Washington State Commission on Pesticide Registration teamed up to investigate the problem. Stacey, diagnostician Jenny Glass, Drs. Marianne Elliott and Gwen Stahnke, and scientific assistant Katie Coats collected 50 samples from 27 Pacific Northwest golf courses during the fall, winter, and early spring. Most of the samples were isolated from annual bluegrass, the predominant putting-surface turfgrass species. The researchers presented their initial findings during the 2011 WSU Turfgrass Field Day July 19 in Puyallup.
So far, Pythium torulosum, Pythium vanterpoolii, and Pythium volutum have been identified as the most common species in the golf course samples. Stacey and the team will continue to culture and sequence all samples, then determine if the pathogens are infectious by reinfecting turfgrass under varying conditions, such as shade, moisture, and soil temperature.
“Why did it happen? I think that question will be answered once we determine what we’re dealing with,” Stacey said.
The larger mystery of Pythium infestation in the Pacific Northwest may yet remain to be solved, but Paz is more than satisfied with the information the WSU turfgrass specialists in Puyallup provided for PLU. She said she would consult them anytime she has a problem in the future. “This is such a great resource for us on the west side. If you want to know anything, this place is set up to give you the answers.”

Pythium Puzzlement Keeps Turfgrass Managers Sleepless

Jim Kerns, University of Wisconsin-Madison Extension specialist of turfgrass pathology, was the featured speaker at the 2011 WSU Turfgrass Field Day July 19

Diseases caused by Pythium are as effective as NO-DOZ® for keeping golf course supervisors awake at night, according to Jim Kerns, the field day’s featured speaker. Some have even blamed this kissing cousin to a fungus for wiping out entire fairways overnight.
Kerns, an assistant professor and Extension specialist of turfgrass pathology at the University of Wisconsin at Madison, broke down three main Pythium diseases for 50 to 60 attendees. The species that causes Pythium blight attacks above-ground foliage; those responsible for Pythium root rot destroy the root system. Still other species cause Pythium root dysfunction, another disease similar to root rot. Control measures are different for each species; a fungicide that works well to treat blight won’t work with root rot, making disease management a challenge. Since Pythium likes warm, wet conditions, cultural practices are also effective in fighting it, including limiting irrigation and increasing mowing height.
Above all, get help from the experts. WSU’s Plant Diagnostic Clinic provides sample processing as well as research and extension information on turfgrass in the Pacific Northwest, primarily west of the Cascade Mountains. For more information, visit
Pythium diseases, especially those that affect the roots, can be very difficult to diagnose in the field,” Kerns said. “Therefore, if symptoms or signs develop that are characteristic of these three diseases, submit samples to a local diagnostic clinic immediately. The best way to combat these diseases is to know which one you are dealing with.”
By Nella Letizia

More than 50 Years of Turfgrass Expertise

One well-known attendee at the July 19 WSU Turfgrass Field Day was Dr. Roy Goss, for whom the research farm that hosted the event was named. The agronomist worked at WSU for 30 years and started the university’s turfgrass science program in 1958. He’s hardly missed a field day since they started in 1959 and was hard to miss among the participants, wearing a white sweatshirt with the WSU Cougar head logo and a crimson baseball hat proclaiming his diamond grad status.

Roy Goss, longtime WSU agronomist and Extension educator for whom the Puyallup turfgrass research farm is named, started the university’s turfgrass science program in 1958.

Goss recalled research highlights easily: how the turfgrass science program contributed to an understanding of nutritional requirements, conducted sand-based rooting profiles that dovetailed with plant pathology work, and identified water use factors. Research expanded to include soil problems resulting from irrigation practices, solutions for soil compaction, and an investigation of sulfur and its relationship with turfgrass quality and diseases.
“Any phase of turfgrass research, we were involved with it,” he said. “School grounds, parks, golf courses, highway greenways, cemeteries, home lawns…”
Because of these contributions, the turfgrass industry in turn supports the WSU program very well by providing grants, equipment, products, and more, Goss added. The Northwest Turfgrass Association, a major program supporter, was instrumental in creating the first WSU researcher position in Puyallup in 1957. Golf course managers are particularly vested in turfgrass studies because this field is very complex and requires a lot of research.
And in those 50 years of doing research and making industry connections, Goss has come to know a lot of people—and friends. “It’s been a good ride,” he said.