Poa annua Is Starting To Get Nervous

By Larry Gilhuly, director, Northwest Region
August 27, 2012

Human beings have walked on the moon. Computers have taken over how we communicate and many other aspects of our lives. But selective control of Poa annua in bentgrass putting greens still does not exist – at least not yet.

Those who have read my article, FLOG - What Turfgrasses Would Call It If Given A Choice, know that I suspect turfgrass plants speak to each other. I’m convinced the main topic of discussion these days among Poa annua plants is a new chemical - methiozolin. So why is Poa annua nervous, even in the near ideal growing environment of the Pacific Northwest? Early experimental use of methiozolin indicates the future could be very interesting regarding Poa annua reduction on bentgrass putting surfaces.

There have been many products available for the reduction of Poa annua, but none have successfully and consistently removed this grass from bentgrass greens. Methiozolin, a new entry into the anti-Poa annua crowd, is being tested at several universities with tests going out at over a dozen golf courses in the Northwest Region. This product may have exactly what is desired for removing Poa annua from any established turfgrass surface.

Results at Washington State University were viewed earlier this year and recently confirmed by Todd Lupkes, superintendent of the Palouse Ridge Golf Course at WSU, and Charles Golob, research associate in the WSU turfgrass management program. The material appears to be very effective in removing Poa annua slowly from bentgrass greens with three applications spaced approximately two weeks apart. Very little turf discoloration and no bare areas were noted. How can that be? Apparently it has everything with how the chemical selectively interacts only with Poa annua by disrupting the cell wall biosynthesis. As a result, the Poa annua plants cannot compete with the actively growing bentgrass.

What about the Poa annua seeds lurking in the soil profile waiting to germinate? This is where this chemistry becomes very interesting. Based on greenhouse studies completed at WSU, methiozolin also has very distinct preemergence characteristics. For this reason, golf courses with high percentages of Poa annua are not good candidates for the trial use of this product. The sites granted EUP’s (Experimental Use Permits) beginning in the fall of 2013 or the spring of 2014 have very high bentgrass/fescue populations. However, there is at least one exception to this conservative approach. Wildhorse Resort in Pendleton, Oregon has as much as 40 percent Poa annua on their greens and Superintendent Sean Hoolehan is working with the product. Will it leave bare areas or slowly transition back to creeping bentgrass? Based on my personal observations after visiting Wildhorse in late July, I’m thinking the latter.

When the individual research plots on the practice green were first viewed at Wildhorse (whose greens were originally planted to Providence bentgrass) there was no discernible color difference between the plots. From the four check plots to the four with the highest rates, and every combination in between, there was no discernible color difference approximately one month after the last application. However, when we referred to the plot plan describing the location of each plot in the research study, there was a noticeable overall reduction in Poa annua in the four plots with the highest rate of methiozolin. This was easily noticeable since Sean has also instituted a Trimmit® program. The reduced growth and minor discoloration from the Trimmit® applications was the perfect visual comparison to the differences noted between the various methiozolin plots.

Even though all of the Poa annua had not been removed from the plots treated with the highest rate of methiozolin, the reduction in Poa annua was obvious when compared to the other plots. The question now is, “Will this occur as smoothly at other golf courses in the future?” While that remains to be seen at least in the Pacific Northwest the Poa annua is beginning to get nervous.

Larry Gilhuly has spent the last 29 years making Poa annua feel both comfortable and nervous at golf courses throughout the western states. He and his fellow agronomist Derf Soller would be happy to do the same at your golf course. Contact them at lgilhuly@usga.org or dsoller@usga.org on this or any other topic related to your golf course maintenance program.

Partner Links
AmEx image
AmEx image
AmEx image
AmEx image

The USGA and Chevron have committed to using the game of golf to encourage students in science, technology, engineering and math (STEM) disciplines. This commitment has led to the creation of extensive golf-focused STEM teaching tools, and has resulted in charitable contributions to support golf-related programs through Eagles for Education™

At U.S. Open Championships the Chevron STEM ZONE™ is an interactive experience highlighting the science and math behind the game of golf through a variety of hands-on exhibits and experiments.

The partnership has also produced educational materials such as the Science of Golf video series and a nationally-distributed newspaper insert which are provided to teachers as tools to enhance existing curriculum in schools. These lessons teach the science behind the USGA’s equipment testing, handicapping, and agronomy efforts.

For more interactive experiences featuring golf-focused STEM lessons, visit the partnership homepage.

Chevron image

Rolex has been a longtime supporter of the USGA and salutes the sportsmanship and great traditions unique to the game. This support includes the Rules of Golf where Rolex has partnered with the USGA to ensure golfers understand and appreciate the game.

As the official timekeeper of the USGA and its championships, they also provide clocks throughout host sites for spectator convenience.

For more information on Rolex and their celebration of the game, visit the Rolex and Golf homepage.

Rolex image

IBM has partnered with the USGA to bring the same technology, expertise, and innovation it provides to businesses all over the world to the USGA and golf's national championship.

IBM provides the information technology to develop and host the U.S. Open’s official website, www.usopen.com, as well as the mobile apps and scoring systems for the three U.S. Open championships. These real-time technology solutions provide an enhanced experience for fans following the championship onsite and online.

For more information on IBM and the technology that powers the U.S. Open and businesses worldwide, visit http://www.usopen.com/IBM

AmEx image

Lexus is committed to partnering with the USGA to deliver a best-in-class experience for the world’s best golfers by providing a fleet of courtesy luxury vehicles for all USGA Championships.

At each U.S. Open, Women’s Open and Senior Open, Lexus provides spectators with access to unique experiences ranging from the opportunity to have a picture taken with both the U.S. Open and U.S. Women’s Open trophies to autograph signings with legendary Lexus Golf Ambassadors in the Lexus Performance Drive Pavilion.

For more information on Lexus, visit http://www.lexus.com/

AmEx image
American Express

Together, American Express and the USGA have been providing world-class service to golf fans since 2006. By creating interactive U.S. Open experiences both onsite and online, American Express enhances the USGA’s effort to make the game more accessible and enjoyable for fans.

For more information on American Express visit www.americanexpress.com/entertainment

AmEx image