Promising Poa Products On The Horizon

By Jim Ross, Prairie Turfgrass Research Centre

Research at a number of universities in the United States on a new product for the reduction of annual bluegrass (Poa annua) in creeping bentgrass is causing quite a bit of excitement for golf course Superintendents.

Studies on the new herbicide, PoaCure (active ingredient methiozolin 25%), has shown to have great effectiveness in the reduction of annual bluegrass without injuring creeping bentgrass.  This is a relatively new herbicide that was originally developed in South Korea for weed control in rice.  It was registered in that country in 2010 for annual bluegrass control in creeping bentgrass greens, and Kentucky bluegrass and perennial ryegrass fairways.

An internet search reveals considerable information on testing that has been conducted in the United States.  At this point, there is no testing being conducted in Canada.  However, according to Kyung-min Han, PoaCure Development Manager, they are working to get an experimental permit and that testing should commence either later this year or next.

The search showed that much of the testing is demonstration testing at various golf clubs.  However, there are a couple of important studies where actual data as collected and the results appear to be quite promising.

Dr. Bill Johnston and Charles Golob, from Washington State University, began their studies in the fall of 2010 to assess the product at two local golf clubs.  Single and multiple applications were applied three weeks apart at either 7.5 or 15 grams active ingredient per 100m2.  The first application was made in mid-September.  Initially, the first putting green had an annual bluegrass population of 2-3%, while the second had a population of 25-30%.

Results showed that there was a 90% reduction at both sites when assessed the following year on three rating dates in May, July and September.   Just as importantly, there appeared to be no noticeable bentgrass injury the following spring and summer.  The late fall application at the high rate did show slight discolouration and thinning of the bentgrass, however, the green recovered quickly.

Another study conducted at the University of Maryland also showed very good results.  Two separate tests were conducted:  one that tested the postemergent properties of the herbicide, while the other study looked at both preemergent and postemergernt applications.  Dr. Peter Dernoeden wrote a very informative article a few years ago that discussed annual bluegrass germination and that it occurred mainly in late summer or early fall.  He felt that if an application was made in the fall prior to germination and then again in the spring that the best possible scenario for control would be examined.

In the pre/post emergent study, a single application was made in early September and then successive applications were made the following spring three weeks apart.  When rated June 1, PoaCure, at 10g a.i. 100m2, had reduced populations by 90% while those plots that were left untreated had an increase in annual bluegrass of 68% .  In the postemergent study, two early season applications reduced annual bluegrass 75% in year one and 95% in year two.  These applications were made without causing significant injury to the creeping bentgrass.

In the postemergent study, the PoaCure was compared with Xonerate 70DF (active ingredient amicarbazone).  Unfortunately, it was only somewhat effective and created considerable injury to the turf particularly at higher temperatures.

It seems that information from these two studies showed effective control at either the 10 or 15 g a.i. rate.  Above all, the product was effective and showed minimal injury to the creeping bentgrass; great news in both areas.

Presently, the only herbicide that is registered in Canada for the control of annual bluegrass is Velocity (bi-spyribac-sodium).  We conducted numerous tests at the Prairie Turfgrass Research Centre with this product and only had effective control on one occasion.  The lack of success was very disappointing, particularly when our first study showed promise!

Research on the herbicide, Velocity, for the reduction of annual bluegrass in creeping bentgrass. Research is conducted on small plots in order to test effectiveness and to reduce the damage to creeping bentgrass.

A product launch for PoaCure in the USA will not be for at least another year and even further off for Canada.  If you would like further information, search PoaCure.  There is a considerable amount of information on the product and, no doubt, there will be more to come in the very near future.