PoaCure may be the silver bullet that superintendents have been wanting for Poa annual control on putting greens
In 2004, Suk-Jin Koo, a South Korean researcher who received his doctorate from Cornell University, decided to see if the chemical methiozolin had a role in the turfgrass industry.
Originally produced for the rice production market, methiozolin had proven too expensive and was shelved. But for golf courses, early indications are that methiozolin – with the trade name PoaCure in the U.S. – could have a profound impact for those looking to reduce or eliminate Poa annua and Poa trivialis.
PoaCure is produced by Moghu, a South Korean-based company founded by Koo. It should receive Environmental Protection Agency (EPA) approval in time for the 2016 golf season.
According to American superintendents who have tested it on their courses, PoaCure is the type of product that golf course superintendents with Poa problems dream about.
“This is a silver bullet. Yes, this is a game-changer,” said Shawn Askew, extension specialist and associate professor of turfgrass weed science at Virginia Tech University, who was the first person to spray PoaCure in the U.S. when he applied it to a research plot in 2009.
According to Askew, the eradication rate of PoaCure is astounding, but the process is accomplished slowly, so bentgrass can fill in as the Poa declines. The Poa yellows about 25 days after the first application and is dead by about the 50th day.
Askew said that balance was a serious issue with prior products. “If we get slow action we don’t get control; we get fast action and we lose our jobs,” he said.
With PoaCure, Askew said it appears that almost every healthy, mature variety of bentgrass is safe. Damage, though, has been seen on areas of heavily shaded bentgrass, in Colonial and Velvet bents, and Providence bent. PoaCure also affects seedlings less than 6 to 7 weeks old of all turf varieties.
For the past three years, golf courses throughout South Korea have been applying it, with nearly half of the 400-plus layouts now using it, according to the company. This number is more notable because of the fact that roughly 50 percent of the courses in South Korea are turfed with bermudagrass or zoysiagrass and can reduce Poa with existing products. The product is sold as PoaBaksa in South Korea.
According to Askew, the pesticide registration process in South Korea and Japan, where the product is scheduled to make it to the market in 2014, is more stringent than in the U.S. He said that about one-third of the toxicology work for the Korean permit will be accepted by the EPA. Methiozolin is a new class of chemistry.
Under trial
This spring, a two-year Experimental Use Permit (EUP) trial is scheduled to get underway on 164 courses that will be allowed to treat up to 6 acres with PoaCure. It will cost each course $1,000 to participate in the program, but, according to the company, the money will be donated to the turf program of a state university where the golf course is located.
Askew said the EUP trials are unnecessary, and he believes unprecedented in the registration process of a turf or ornamental herbicide. According to Askew, Koo wants to conduct the EUP to prove PoaCure’s overall safety. Askew said Moghu will lose about $250,000 by conducting the trials. After the disaster DuPont had with Imprelis, it’s easy to understand why Koo would want to take such a step.
“There has been nothing to suggest it is harmful to the environment,” Askew stated. “All it is is a benefit to the end user.”
Although the primary mode of action for methiozolin has not been determined, Askew and other researchers are sure that it inhibits biosynthesis in the plant cell wall. It also appears to have pre-emergent and postemergent action.
Positive response
What U.S. superintendents have seen on their courses has them touting PoaCure. Some courses participating in the EUP were given enough chemical to treat 2,000 square feet in 2013.
At Oconomowoc (Wis.) Golf Club, superintendent Dustin Riley manages a course that has 17 original greens dating back to 1916, and three sand-based greens, two for practicing. The older greens, designed by Donald Ross, are an amalgamation of turf. The newer greens have Providence bent. He noted that there’s about 5 to 15 percent Poa on his putting surfaces.
On Oct. 1, 2012, Riley applied PoaCure at the recommended rate of 0.6 ounces per 1,000 square feet to a strip through the center of one of the original greens. Within the test swath, he placed a floor mat to act as a control area. PoaCure was put down on Oct. 14 and Nov. 1 at the same rate.
Riley said he first saw discoloration of the Poa at the end of November, but it still appeared healthy. In the spring, though, Riley was stunned by the results.
“Anything we treated was gone, like it melted away,” he said. “It’s ridiculous.”
Not only was the Poa dead, but the bent had filled in so there were no bare spots. According to Riley, the Poa didn’t return over the course of the season, but where the mat had been the Poa thrived. The control lasted into the winter. “We didn’t see any fall germination,” Riley added.
He had some of the chemical leftover from the original trial and applied it to another green three times in the spring. This time it didn’t seem to have any effect on the Poa, he said. Other superintendents, however, saw control after a spring application.
The only hint of a downside with the product, according to Riley, came when representatives of the University of Wisconsin applied PoaCure with a walk-behind sprayer and some yellowing of bentgrass occurred, possibly a variety of Velvet seeded in the green decades ago. But the bent recovered.
“It did not deter my belief in the product,” said Riley, who’s scheduled to be part of the EUP.
Scott Niven, superintendent at The Stanwich Club in Greenwich, Conn., will also be participating in the trial. Niven also had a trial sample of PoaCure and found three spring applications to be highly effective on greens that have about 5 percent Poa. He initially applied it to “hot spots,” and then on the putting green, applying with a Spray Hawk.
According to Niven, on the areas that received PoaCure, the intended target was “100 percent gone. You think you see something and it’s gone,” he said.
There was also no adverse effect on the bent.
“It’s like putting water on bentgrass, you can’t see anything. We couldn’t even see a line,” Niven said.
Moghu’s only representative in the U.S. is Development Manager Kyung-min Han, who graduated from Rutgers University in 2008 with a bachelor’s degree in turf and a master’s degree in agronomy. Part of his master’s thesis involved running trials with methiozolin.
After graduation, Han was an assistant superintendent at White Beeches Golf and Country Club in Haworth, N.J. He’s now based in Palisades Park, N.J.
Han has been traveling around the U.S. to courses that have been able to test PoaCure and will oversee the EUP trials.
“We want to customize a program for each golf course,” Han said, which is something the company intends to do when the product comes to market.
According to Han, it will take three to five years of applications to get the desired results. “We want to make sure we don’t build resistance quickly,” he added.
Han also hinted that there are other products being developed by Moghu that will complement PoaCure and stave off resistance.
“That’s the right way to do it … tailor it to every golf course,” said Pat Finlen, general manager at the Olympic Club in San Francisco, Calif., and past president of the Golf Course Superintendents Association of America (GCSAA). “If you’ve got 30 percent [Poa], you have to be careful because you will end up with 30 percent bare ground.”
Since 2011, Jim Baird, turfgrass specialist at the University of California/Riverside, has been testing PoaCure on all three courses at the Olympic Club: the Lake, which was sodded to bent in 2009; the Ocean, which was sodded with bent in 2012; and the Cliffs course, which still has Poa greens.
PoaCure was first applied on the Lake Course in 2011. “It took out every bit of Poa out there,” Finlen noted. He estimated that Poa made up about 5 percent or less of the stand.
According to Finlen, PoaCure could have a ripple effect across the golf maintenance industry. Environmentalists may be opposed to a new class of pesticides, but the use of methiozolin might reduce other inputs, such as water, fertilizer and pesticides, that are needed to keep Poa alive during stressful periods, such as the height of summer heat and humidity. Even if the annual cost per golf course was in the range of $10,000 to $15,000, much of that could be offset by the reduction of other inputs.
As impressed as he is, Finlen is not ready to pronounce PoaCure the be all and end all of annual bluegrass control. He wants to see the results of the two-year EUP trials. However, he is optimistic it could have a significant effect on the industry.
“I think it’s got the potential,” Finlen said. “We have seen so many great products, from growth regulators to herbicides and fungicides, that have allowed us to manage golf courses in a much better way environmentally; this could be another one of those. I think it’s got the potential.”