PACE Turf - Turfgrass Information Center

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Evaluation of Proxy as a Poa Seedhead Inhibitor

Summary: Following up on 1999 trials that demonstrated the efficacy of ethephon (Proxy) as a Poa annua seedhead inhibitor, six replicated field trials were conducted at four different golf course locations during 2000.  Both cool season putting greens and overseeded fairways served as test sites for the continued evaluations of the seedhead inhibitory effect of ethephon, and ethephon combinations with trinexepac-ethyl (Primo).  Key results include:

  • The use of Proxy at rates of either 5 oz or 10 oz/1000 square feet resulted in a significant decrease in the density of Poa annua seedheads.  This effect was observed for as long as seven weeks after a single application of Proxy.
  • A single application of Proxy at 5 oz/1000 sq ft resulted in significant suppression (45-85%) of poa seedheads on golf course greens and fairways.
  • There was a lag time of approximately 3 weeks before significant seedhead suppression was observed .
  • Suppression with the 5 oz rate of Proxy declined to <50% by 7 weeks after treatment
  • The level of seedhead suppression was positively correlated with rate, with the 3 oz rate of Proxy resulting lower suppression (10 – 55%) and the highest rate (10 oz/1000 sq ft) resulting in the highest levels of suppression (up to 97%)
  • The addition of Primo (>0.060 oz/1000 sq ft) to Proxy (5 oz/1000 sq ft) resulted in a significant increase in seedhead suppression, as well as improved turf quality on golf course greens
  • When used by itself, Primo had little or no effect on seedhead suppression
  • Embark (mefluidide) provided very good poa seedhead suppression, and is the standard product currently used for this purpose on all poa greens (Table 3). However, the product had to be applied every 3 weeks, and significant (though reversible) turf discoloration resulted.  This product causes signficant damage to bentgrass and is therefore not utilized on greens containing bentgrass.
  • Timing Proxy applications to target early seedhead formation (January/February in coastal and inland Southern California) appears to result in better seedhead suppression than applications made later in the season (March/April). The higher temperatures characteristic of the Low Desert may require an even earlier application initiation. Developing optimal timing strategies require further work.
  • Proxy caused no discoloration or phytotoxicity on any of the turf types tested including Poa annua, bentgrass, perennial ryegrass and bermudagrass.
Printable version of full report Principal Investigators: Wendy Gelernter, Ph.D. and Larry J. Stowell, Ph.D., CPPP, CPAg Cooperators:  Gary Dalton, San Diego Country Club; Nancy Dickens, Mountain Vista Golf Course; John Harkness, Oak Valley Golf Course; David Major, Del Mar Country Club Sponsors:  Chris Olsen, Aventis; PACE Turfgrass Research Institute

Evaluation of Proxy as a Growth Regulator and Seedhead Inhibitor on Overseeded Fairways

Summary: In replicated field trials conducted at two locations (The Country Club of Rancho Bernardo, and Admiral Baker Golf Course), the effect of the experimental product ethephon (Proxy) on turf quality, turf growth regulation and Poa annua seedhead inhibition was evaluated on bermudagrass fairways that had been overseeded with perennial ryegrass. Key results include:

  • The use of Proxy at rates of either 5 oz or 10 oz/1000 square feet resulted in a significant decrease in the density of Poa annua seedheads. This effect was observed for as long as seven weeks after a single application of Proxy.
  • Primo L (0.5 oz/1000 square feet) also resulted in decreased poa seedhead densities, but this effect was neither as strong nor as consistent as that for Proxy.
  • Overall, Proxy applications performed inconsistently in the regulation of cool season turf growth on overseeded bermudagrass fairways. While the 5-oz rate produced significant clipping weight reductions at one location, it took several weeks for the effect to appear. The 10-oz rate of Proxy resulted in significant increases in turf growth on several evaluation dates. This unexpected result was observed at both test locations.
  • No phytotoxicity was caused by any of the products tested, although Primo L (0.5 oz/1000 square feet) caused a dark colored cast to appear on treated plots due to growth inhibition and stress caused on senescing bermudagrass. The lack of any damage to bermudagrass or ryegrass caused by Proxy, in combination with its ability to reduce poa seedhead densities, may make it a valuable tool in golf course poa management on fairways and greens,despite its disappointing performance as a cool-season turf growth regulator.

Printable version of full report

Principal Investigators: Wendy Gelernter, Ph.D. and Larry J. Stowell, Ph.D., CPPP, CPAg

Cooperators: Alan Andreasen and Mike Magnani, Admiral Baker Golf Course; Sandy Clark, The Country Club of Rancho Bernardo

Sponsor: Chris Olsen, Rhone-Poulenc

 

Evaluation of Chipco Proxy and EXP 310309 for Use as a Turf Growth Regulator on Kikuyugrass Fairways

Summary: In replicated field trials conducted on a kikuyugrass nursery that was mowed at fairway height, the effect of the experimental product ethephon (Proxy) or a combination of ethephon plus cyclanilide (EXP 310309) on turf quality, turf growth regulation and scalping was evaluated. Key results include:

  • A single application of Proxy at either 5 oz or 10 oz/1000 square feet had little or no effect on growth regulation of kikuyugrass, with significant clipping reductions observed on only one (5 oz rate) or two (10 oz rate) out of a total of six sampling dates. The addition of cyclanilide to ethephon, in the form of EXP 310309, had a small but positive effect on performance, with significant clipping reductions observed on two sampling dates (2.5 oz rate) or three sampling dates (5.0 ozrate). However, in contrast, Primo L (0.5 oz/1000 square feet) resulted in significantly reduced clipping rates on all six sampling dates.
  • Turf quality was not improved through application of Proxy or EXP310309 at any of the rates tested. In contrast, Primo L (0.5 oz/1000 square feet) produced turf with significantly improved quality (when compared to the non-treated check) on all six sampling dates.
  • The degree of scalping (appearance of brownish, stubbly, unisghtly areas, as a result of mowing) of kikuyugrass was not consistently reduced through application of either Proxy or EXP310309. In contrast, application of Primo L resulted in signficant reductions in scalping on all sampling dates.
  • In general, EXP310309 performed slightly better than Proxy in terms of growth regulation, turf quality and reduced scalping, suggesting that the addition of cyclanilide to ethephon has a beneficial effect. However, the improvement in performance was small, and still did not result in commercially acceptable performance. For these reasons, neither product was judged to demonstrate commercial viability for use as a growth regulator on kikuyugrass fairways.

Printable version of full report

Principal Investigators: Wendy Gelernter, Ph.D. and Larry J. Stowell, Ph.D., CPPP, CPAg

Cooperator:  Bruce Duenow, La Jolla Country Club, La Jolla, CA.

Sponsor:  Chris Olsen, Rhone-Poulenc

 

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