Researchers Testing a Better Way to Control Microdochium Patch on Putting Greens

Microdochium patch.

Microdochium patch, or Fusarium patch as it’s also known, is a problem for golf courses in cool-weather climates like the Pacific Northwest. The fungus creates dinner-plate-sized dead spots on putting greens that are both ugly and can send putts off course.

Control used to mean regular applications of synthetic fungicides – every three to four weeks nine month out of the year – or about 15,000 applications just in the Pacific Northwest alone. That costs the typical golf course about $20,000 a year.

However, new research conducted by Oregon State University’s Alexander Kowalewski and funded by the Western IPM Center is developing ways to manage Microdochium patch that are both better for the environment and far cheaper for course managers.

Kowalewski and graduate research assistant Clint Mattox found that combining a commercial crop oil developed for turfgrass disease and insect suppression, Civitas One, with sulfur or potassium phosphite was very effective at controlling Microdochium patch. They also determined that applications of iron sulfate plus light rates of nitrogen were equally effective.

“Our untreated test plots had about 40 percent disease,” Mattox explained. “The plots treated with Civitas One and sulfur, many of them had no disease, and some had just one percent disease. It’s as effective as synthetic fungicides.”

The research is being successfully replicated at Washington State University, as well.
Kowalewski said the research also showed a surprising finding – that nitrogen applications to greens through the winter can be good.

“The traditional recommendation is to stop nitrogen applications through the winter,” he explained. “What we’re seeing is that the turf is better off with some additional nitrogen.”

Further, the researchers estimate these treatments would save the typical golf course more than $14,000 a year, which translates to a savings of $4.5 million in Oregon, Washington and Northern California alone.

One part of Mattox’s research is recreating the foot traffic a typical putting green sees during the week, so for five days a week, he’s out walking over particular test plots in his golf shoes.

“One day I’m out for 86 minutes, one day 20 minutes, one day 10 minutes, one day six minutes and one day five,” he said. “It simulates 73 rounds of golf.”

Mattox, who came to Oregon State after several years as a golf course manager in Europe, said a non-synthetic management option is especially important there.

“Europe is really tightening down on pesticides,” he said. “We’re starting to see those pressures in the States as well, so another IPM option will be welcomed.”

Both Civitas One and the sulfur being used in the tests are approved for organic production. Potassium phosphite is labeled as a synthetic fertilizer, so is not organically approved.

Over time, the sulfur, potassium or iron would increase the acidity of the soil and eventually damage the greens as well, so the next step in the research will be to test ways to buffer the acidity of the treatments with various calcium sources and to make sure that these treatments for a winter disease don’t cause unexpected problems in the summer.