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For some, pythium blight is a job-killer

In today’s lesson in golf science we pay a visit to Gwen Stahnke, for whom a normal day’s work might include waiting on Koch’s postulates to play out.

Koch’s postulates, as we all know, are four criteria designed to establish a causal relationship between a microbe and a disease. In this case, the microbe is pythium, and the test subject is healthy grass from a local putting green.

In a nutshell (or petri dish, if you prefer), if the pythium infects the healthy grass, then Stahnke, a turfgrass scientist at the WSU Extension in Puyallup, will know it’s a strain of cool-weather pythium that’s been damaging the poa annua greens around the region.

In all seriousness, this obscure terminology represents serious science. And pythium blight is a deadly serious subject in the world of golf course superintendents.

“Pythium is known as a warm-weather disease, but over the past couple years a (once) weak strain of pythium is now fairly destructive,” Justin Ruiz, superintendent at Olympia’s Indian Summer Golf and Country Club, wrote in an email recently.

Ruiz estimates some 24 golf course superintendents are dealing with pythium blight.

“Some have lost their jobs, and others are hanging on,” Ruiz wrote.

Ruiz and Indian Summer are taking part in a wetting agent study to see if “moving the water through the profile” (science talk again) will help with the infection.

What’s happening, according to WSU’s Stahnke, is a perfect storm of plant pathology.

The extended hot summer of 2009, when temperatures stayed near 100 degrees Fahrenheit much longer than typical west of the Cascades, then stayed warmer at night, caused supers to water more than usual just to keep the greens going.

The hot summer gave way to a cold 2010 winter, which did its own damage.

This winter was cold and wet, and the extended wet spring has done its part. Stahnke and her clients in superintendents’ offices at first didn’t recognize the yellowish fungal blooms on the greens as pythium.

Not every fungicide works on every fungus, so it was not as simple as point-and-shoot.

“What happened was it just hung in there,” Stahnke said. “It had nothing to do with what any one superintendent did.”

At clubs where the members are particularly demanding, pythium has become less a question of horticultural science than job security.

Particularly at private courses, club members are more demanding than ever of superintendents. Members see tournaments on TV where the Stimpmeter rolls at 12 or 13 feet, and they want their greens that fast all the time, Stahnke said.

Grass isn’t designed to be kept that short, and that puts extra stress on greens that are already compromised.

So the challenge, for Stahnke and her clientele, is to show that this is a virulent infectious disease and not neglect by superintendents.

Which brings us back to Koch’s postulates, first published by Robert Koch in 1890. He used the test to determine the causes of anthrax and tuberculosis, and the postulates have since been applied to many other diseases.

Including, in 2011, pythium blight.

Source: www.theolympian.com

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