PACE Turf - Turfgrass Information Center

Cultural

Evaluation of Fungicides and Wetting Agents for the Management of Localized Dry Spot and Fairy Ring

Summary: In a replicated field trial conducted on a bentgrass (Pennlinks) practice putting green at Del Mar Country Club, Rancho Santa Fe, CA, the wetting agents Respond and Primer and the fungicides Heritage and ProStar were evaluated for their ability to control localized dry spot (LDS) and fairy ring caused by the fungus Agrocybe pediades. Key results included:

  • The fungus Agrocybe pediades, which produces small brown mushrooms, was identified from non-treated plots. This fungus is frequently associated with fairy ring symptoms in Southern California.
  • Two types of symptoms were detected in the plots: 1) Type B fairy ring symptoms: dark green circles of stimulated turf growth, with thatch degradation leading to low spots in the turf, and 2) Type C fairy ring (also frequently called localized dry spot) symptoms: dry spots with irregular areas of dead or dying turf and extreme hydrophobicity underneath.
  • Respond G and Primer significantly reduced the incidence of LDS (Type C fairy ring) symptoms. However these products applied by themselves had no effect on the incidence of Type B fairy ring symptoms.
  • Both Type B and Type C fairy ring symptoms were controlled best by monthly applications of ProStar (6 oz/1000 sq ft) plus the wetting agent Respond (3 oz/1000sq ft) (no posttreatment irrigation) and by monthly applications of Heritage (0.4 oz/1000 sq ft) plus the wetting agent Respond L (3 oz/1000 sq ft) (with post-treatment irrigation). Performing almost as well were monthly applications of Heritage (0.4 oz/1000sq ft), with or without post-treatment irrigation, and Heritage plus Respond (with no posttreatment irrigation).
  • It is important to note that while wetting agents can manage the symptoms of LDS (as can cultural practices such as verticutting, aerification, topdressing and hand watering), a fungicide such as ProStar or Heritage is necessary to kill the fungus that causes dry spot and fairy ring.
  • For reasons that are not clear, turf phytotoxicity occurred when monthly applications of ProStar (6 oz/1000 sq ft) were made without the addition of Respond L. This appears to be a unique observation, since ProStar is typically applied on golf courses, including Del Mar Country Club, under these same conditions with no negative results. We are working with AgrEvo to better understand this effect.

Printable version of full report

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

Cooperator: David Major, Del Mar Country Club

Sponsors: Mike Fidanza, AgrEvo, David Bower, UHS and Jim Petta, Zeneca

 

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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