Lawn Disease Causing Light, Dollar-Size Spots

Manhattan, Kansas (September 22, 2006)– The best thing about dollar spot – a plant disease now active in an array of central U.S. lawns and golf courses – is that it usually doesn’t attack tall fescue, a Kansas lawn turf favorite. Dollar spot shows up, however, in everything from Kentucky bluegrass and perennial ryegrass (cool-season grasses) to bermuda and buffalograss (warm-season turfs).

“In lawns, dollar spot causes small, round patches that look bleached. In low-mowed golf-green-type turf, the disease causes tan patches that are about the size of a silver dollar,” said Megan Kennelly, plant pathologist with Kansas State University Research and Extension.

On individual grass blades, the disease also causes tan or yellow spots with brown margins.

“Cool, wet weather favors the development of this disease,” Kennelly said, “especially cool nights with heavy dew that remains on leaves into the morning.”

That makes early fall a prime time for dollar spot to appear, she said. Lawn turf owners may overlook the problem, however, amid the other color changes emerging as many lawn weeds decline and as warm-season grasses start to shut down for winter.

“If you go out on a dewy morning, though, and you look closely, you’ll see white, fuzzy fungal growth at the edge of the dollar-size spots with the disease,” Kennelly said.

Homeowners don’t have access to most dollar spot controls, she warned. Licensed commercial applicators can buy a range of such fungicides, but can’t legally apply many of them on home lawns.

“Fortunately, homeowners can do a lot to prevent the disease from coming back, year after year,” Kennelly said. “The first step is to fertilize, as recommended for your lawn. Dollar spot likes lawns with low nitrogen – low soil fertility.

“The second step is to avoid watering in late evening or at night. That way you won’t create long dew periods to add to those that nature provides.”

For more information on dollar spot, go to www.plantpath.ksu.edu. Click on Extension, then Factsheets.

Contact:

Megan Kennelly
785-532-1387