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

Cultural, PGR,

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.

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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