Chipco Professional Products Hosts First-Ever Poa Summit

While the overall goal of the meetings was to identify research needs for Poa annua management, the Summit had four specific objectives:

1. Share information on Poa management, control and suppression with others who have the same interest;
2. Compare Poa management practices in different geographical regions;
3. Discuss importance of Poa biology and biotypes; and
4. Evaluate program approaches used to control Poa, including various products.

Also known as annual bluegrass, Poa annua is prevalent in lawns and gardens, particularly those with moist, rich soils. While generally a suitable grass for professional turf, Poa annua becomes an eyesore upon seedhead germination. The grass produces white seedheads at a prolific rate, making Poa annua appear as white patches amongst professional turf types. Because of its prolific rate of seedhead production, Poa annua spreads quickly, making it a difficult grass to control.

There are currently two schools of thought regarding Poa annua in professional turf. One calls for the control and elimination of Poa annua populations using pre- and postemergent herbicides. The other takes into consideration the difficult task of Poa control, instead calling for the management of Poa annua seedheads using plant growth regulators (PGRs), which slow growth and control the appearance of seedheads.

Stanley Zontek of the United States Golf Association (USGA) Green Section, Mid-Atlantic Region, opened up the Summit with his presentation "Poa annua: Friend or Foe?" Zontek took attendees through a history of annual bluegrass, discussing the background of the turfgrass in the context of his 30 years of experience with USGA.

Poa Summit attendees discuss plot testing at Pinehurst’s No. 7 course.

The studies of T. Karl Danneberger, Ph.D. of the Ohio State University have found that annual bluegrass populations have diverged not only with traits that are highly selective but with neutral traits as well. Danneberger’s studies have attempted to utilize weaknesses in the physiological ecology of annual bluegrass for control purposes.

Danneberger’s presentation documented his attempts to identify the different varieties of Poa annua in different areas and to distinguish their growth patterns.

Controlling Poa annua in the northern United States has proven to be very difficult on cool-season golf courses. There are two principal reasons for this difficulty - lack of reliable postemergent control for Poa annua and, equally important, the requirement by most golf course superintendents that the playability and aesthetics of the golf course be maintained during the control process. Most golf courses have developed a Poa annua problem over many years with populations of Poa annua exceeding 50 percent; the use of an effective postemergent herbicide can result in unplayable course conditions. Bruce Branham, Ph.D. of the University of Illinois examined Poa annua control strategies in the Midwest - both biological and chemical.

Branham’s research has centered on the use of herbicides at various stages of Poa annua control - from preemergent applications to postemergent Poa control, as well as seedhead suppression usage. Overall, Branham recommended several uses for some products:

1. For use on new turf to keep Poa annua out;
2. For use to control Poa seedheads;
3. For use on turf in renovating areas; and
4. For use after Poa annua populations have been reduced by other means.

In his presentation titled "Management Strategies in the Western Region," Mark Mahady of Mark M. Mahady & Associates Inc. shared research results of field trials he has conducted over the last eight years involving several herbicides and plant growth regulators. Mahady’s presentation attempted to answer two important questions:

Attendees practice their putting on the Clayton Farm test green.

1. Should we attempt to control Poa annua in our attempt to improve turf quality?
2. Should we accept Poa annua, manage it and attempt to improve surface quality by enhancing overall uniformity relative to other desirable turf types?

Mahady presented field trials of Poa annua control products at Pebble Beach, Desert Dunes and Spanish Bay country clubs in perennial ryegrass on annual biotypes of annual bluegrass.

Among the three PGRs used in his trials, Mahady’s research showed that one exhibited 89-96 percent seedhead control 14-28 days after treatment. Those applications also showed greens to be more visually dynamic and more forgiving in timing than other seedhead suppression products.

In his presentation "Management Strategies in the Southern Region," Fred Yelverton, Ph.D. of North Carolina State University discussed Poa annua management in various Southern turf types, including nonoverseeded warm-season turf, dormant Bermudagrass, nonoverseeded Bermudagrass, overseeded Bermudagrass and bentgrass. Yelverton has tested various herbicides for their effectiveness in different turf types with varied success. He presented his research results on Poa annua control, with a wide variety of herbicides including Dimension®, Ronstar®, Barricade, Kerb®, Roundup®, Finale®, Atrazine, Simazine, Balan® and Surflan®.

G. Euel Coats, Ph.D. from Mississippi State University addressed the issue of herbicide resistance in his presentation "Poa Resistance to Herbicides." Coats analyzed the chemistry of Poa annua control products to address current and potential herbicide resistance issues in regard to Poa annua control. He reviewed current Poa control products, discussing any resistance issues these herbicides may already have.

The most productive portion of the three days of discussion may have been the regionalized meetings on April 11, in which researchers from across the country discussed regional Poa annua management strategies. In the Midwest, it was agreed that Poa was too tough and widespread for control. The best strategy for Poa annua was management using PGRs. Researchers in the Pacific Northwest agreed, encouraging the growth and management of Poa annua with PGRs. In California, a mixed strategy of control and management was adopted. For early Poa breakouts, an herbicide application would be effective. However, once Poa annua infestation has reached 30 percent of turf, the researchers encouraged turf managers to push to get that number up to 100 percent. At that point, management of the grass via PGR usage was the best option.

"Comparing regional control and management strategies showed the variability in performance of similar programs in different regions," commented Mahady. "In California we have both cool and warm season grasses, so all regional discussions related to our needs in some manner."

More than just research, the Summit was an opportunity for researchers to meet with colleagues from throughout the country with whom they shared a common interest. The Summit included presentations, individual and group discussions and field trips. Chipco Professional Products and its predecessor companies have had a long-standing interest in the control of annual bluegrass. The Summit reinforced its commitment to support research that solves practical turf problems that professionals face every day.

"I think it is important to know what academic and industry personnel are saying on such a visible topic like annual bluegrass," said Danneberger. "Since we are all making recommendations to turfgrass professionals, it’s good to know where our peers stand and what new research is currently going on."