Paul Peterson, left, and Bruce Martin looks over a greenhouse table filled with turf samples, some diseased and some not.

DATE: 4/27/2006

CONTACT: Dr. Bruce Martin, (843) 662-3526, ext. 234; sbmrtn@clemson.edu

WRITER: Tom Lollis, (803) 284-3343, ext. 241; tlollis@clemson.edu

Clemson turf pathologist helps coastal golf courses fight blight

FLORENCE – This is the tale of how a mystery disease known as rapid blight threatened golf tourism along South Carolina’s coast and how a Clemson University scientist helped find out what it was and how to control it.

Early in 2000 brown patches from 6 inches to a foot across on putting greens sent the superintendent at the Ocean Course on Kiawah Island to the phone to call Bruce Martin, turf plant pathologist at Clemson University’s Pee Dee Research and Education Center.

“A bit of a border surrounded the patches. It looked like a disease caused by a fungus,” said Martin. Appearances can be deceiving, however.

He and a colleague checked samples under the microscope.

“We couldn’t find a clue. We saw no mycelium or any spores that we would typically see with a fungus,” said Martin. The course superintendent could not control the problem with fungicides. Fortunately the problem was not severe. Cool season rough bluegrass was affected but not the underlying Bermuda grass.

Irrigation water quality was poor, high in salts.

The following spring the problem was reported at a golf course at North Myrtle Beach. It was much worse than what Martin had seen in 2000. Clues were still scarce, but he found out about a turfgrass pathologist named Larry Stowell, who had reported similar problems on putting greens in Southern California.

“They were calling the disease Chytrid, for a type of primitive fungus,” said Martin. “They were seeing a tiny football-shaped organism in bluegrass leaves under the microscope. We looked for them here and found them.”

That fall he put out tests of several different grasses at the North Myrtle Beach course. The disease took out all except for colonial bentgrass and a creeping red fescue.

“By this time the superintendent was desperate. Seed costs were $1.50 a pound. They were overseeding 10-15 pounds per thousand square feet over the whole greens complex, and they were losing it,” said Martin. “It’s a resort, and nobody is going to pay to putt on brown grass.”

Tourists pay well to putt in South Carolina. Golf-related expenditures generate an economic impact estimated at $1.55 billion annually. In the Grand Strand alone, a 60-mile stretch from the Myrtle Beach area to Georgetown County, 4.3 million rounds of golf are played on 120 golf courses each year.

By the time the course had put out an emergency order of bentgrass, Martin noticed that the disease had started taking it out in test plots.

“The disease had killed everything on the other side of the green away from our overseeding trials, so they overseeded again and we put down tests of as many fungicides as we could get,” he said. The goal was to find something active against Chytrid type organisms. A 1940s fungicide called mancozeb showed some promise.

A superintendent in California, where golf courses were having an epidemic of the new disease, mentioned to Martin that he thought he was seeing results from a new product called Compass.

“We put that down, plus an experimental from BASF and one other and ‘Bingo!,’” said Martin. “That gave us something to plug the holes in the dam.” The BASF product has since been labeled as Insignia and shows the most activity for rapid blight. More and more golf courses from the North Carolina line to Hilton Head began reporting the same disease. The further away from the coast, the fewer the problems.

Clemson scientists applied for a $30,000 grant with the U.S. Golf Asociation and got it. That and chemical company funding enabled him to hire Paul Peterson in a post-doctoral position to work on the disease. The organism causing the problem had still not been identified. A literature search had shown the organism found in South Carolina did not resemble any Chytrid.

“In the spring of 2002 I was on the phone with Larry Stowell discussing what to call the disease,” said Martin. “We decided to call it something other than Chytrid, since we didn’t want that hanging around after a proper diagnosis. I suggested quick disease or something like that. We came up with rapid blight, even though we didn’t know what the organism was.”

Several people were trying to figure that out when a pathologist in Arizona, Mary Olsen, showed the organism to an old-time mycologist named Bob Gilbertson, who thought it looked like Labyrinthula zorastae, a salt-loving ocean-dwelling slime mold.

“That had never been associated with a disease of terrestrial plants, but it had been identified as causing a disease of eel grass, which grows in estuaries,” said Martin.

After finding out how to culture the marine slime mold in the laboratory, California pathologists inoculated plants, then treated with saline irrigation water and reproduced the disease. Paul Peterson visited the lab to get pointers on culturing the organism, then he and Martin were able to isolate the organism from the east coast.

DNA analysis of samples from Martin’s lab shows that the organism isolated in South Carolina and 10 other states is genetically different from its marine cousin and has been named L. terrestris.

“Rapid blight first showed up after a lengthy drought,” said Martin. “That concentrated the salts in irrigation water. It hasn’t been as much of a problem in the past two years because we’ve had more rain. It will be back, however, as soon as we have another drought.”

L. terrestris has been identified on 15 courses, but Martin suspects it is on more. Clemson’s advice on fungicides, choice of grasses and water management has helped keep the disease in check.

Martin has helped golf courses with sodium management by recommending the use of gypsum, which is applied to greens and fairways and flushed through the soil profile. That removes sodium from the root zone. Then, nutrients like potassium and magnesium, which also get stripped out, must be reapplied.

“The procedure is hard to do in a drought, but if you get a little rain, it works,” said Martin. “A lot of courses do this routinely now.”

Research on L. terrestris will continue since there is a chance that it could become a problem on other plants and because diminished water quality and quantity is expected to be more of an issue as the population increases.

“Lawns could eventually be affected as well as golf courses,” he said.

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