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Efficacy of herbicides for Poa control on overseeded fairways

Summary: In replicated field trials conducted on common bermudagrass fairways that were overseeded with perennial ryegrass, rates and timing of various herbicides were evaluated for Poa annua control efficacy. Key results include:

  • Pre-emergence herbicides such as Dimension and Barricade continue to be most effective when applied prior to overseeding, as opposed to after overseeding.
  • Applications made post-overseeding required higher rates of Dimension (200 lbs/A of the 0.25G formulation) to achieve the same efficacy observed at lower rates (150 lb/A) applied before overseeding.
  • The efficacy and longevity of split applications was evaluated, but was difficult to assess, due to low populations of Poa annua.
  • None of the treatments tested caused damage to either ryegrass or bermudagrass.

Printable version of full report

Principal Investigators: Wendy Gelernter, Ph.D. and Larry J. Stowell, Ph.D., CPPP, CPAg Cooperators: Nancy Dickens, Mountain Vista Golf Course Sponsor: Rohm and Haas

Effect of Primo on overseeding

As detailed in the Super Journal report, "Evaluation of Primo rates and application: timing strategies for improved transition and turf quality on common bermudagrass fairways" (476 KB pdf document), trinexepac-ethyl can have both positive and negative effects on turfgrass quality. Key findings included:

  • Of the 41 treatments tested (4 rates, 5 timing strategies and single vs. double applications), we found that Primo treatments made at the time of the first ryegrass mowing (on October 23, 1996, or 1 day after the first mowing) resulted in an improved Fall transition from bermudagrass to ryegrass and significantly higher quality ryegrass during the critical winter and spring months than other treatments tested.
  • The most economical of the highest ranked treatments was a single application of Primo Liquid at 0.5 oz/1000 sq feet, applied on 10/23/96.
  • In contrast, Primo applications made later in the Fall (October 30, 1996, or 8 days after the first mow), produced a negative effect on turf quality during the 1997 Spring transition.
  • These results confirm that the currently labeled rate of 0.5 oz/1000 square feet for use of Primo Liquid in overseeding programs is the optimal rate for use in overseeding programs in the Low Desert, but that the currently recommended application timing (1 - 5 days before overseeding) may need to be adjusted. To confirm the results of this study, a 1997/98 trial that re-tests the highest ranked treatments from this year's study is recommended for initiation in September, 1997.

Project title: CEvaluation of Primo rates and application: timing strategies for improved transition and turf quality on common bermudagrass fairways

Principal investigators: Wendy Gelernter, Ph.D. and Larry Stowell, Ph.D., CPAg, PACE Turfgrass Research Institute

Cooperators: Tom Baty, Indian Wells Country Club

Sponsors: Hi Lo Desert GCSA and Novartis


Super Journal Advisory Board

Super Journal was originally established with the guidance of the following turfgrass professionals. Since that time, Dr. Larry Stowell and Dr Wendy Gelernter have continued to steward the online publication archive.

Brian Archbold, El Niguel Country Club
Buzz Barker, Antelope Valley Country Club
Tim Barrier, Rancho Santa Fe Golf Club
Jeff Beardsley, Big Canyon Country Club
Mike Caranci, Candlewood Country Club
Sean Cincotta CGCS, Laguna Woods Golf Course
Sandy Clark CGCS, Barona Creek Golf Club
Jack Aldrich, San Diego Country Club
Brian Darrock, Fairbanks Ranch Country Club
Dennis Fowler, La Jolla Country Club
Mike Gleason, San Luis Rey Downs
Mike Greninger CGCS, Acushnet Test Facility
Pat Gross, USGA
Mike Hathaway CGCS, The Bridges, Rancho Santa Fe
Russell Meyers, The Los Angeles Country Club
Michael Wolpoff, Friendly Hills Country Club
Wayne Mills, La Cumbre Country Club
Robert O’Connell, Brentwood Country Club
Gary Radersma, Country Club of Rancho Bernardo
Reed Yenny CGCS, Hillcrest Country Club

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