PACE Turf - Turfgrass Information Center

Characterization and Management of Bermudagrass Decline on Golf Course Greens

Summary: In replicated field trials conducted on a bermudagrass putting green, fungicides were tested for efficacy and phytotoxicity against symptoms of bermudagrass decline, caused by Gaeumannomyces graminis. Key results include:

  • Summer temperatures that were significantly cooler than normal contributed to a lack of disease pressure at this site. Weak decline symptoms (irregularly shaped chlorotic patches, with both roots and foliage affected) were observed in the non-treated plots, and the presence of Gaeumannomyces was confirmed microscopically. However, damage due to disease in the non-treated plots was not significantly worse than in fungicide treated plots.
  • As a result of lack of disease pressure, it was not possible to judge the products tested for their efficacy in controlling symptoms of bermudagrass decline.
  • Applications of the sterol inhibitor fungicide Eagle produced significant phytotoxicity, probably as a result of a maximum air temperature of 100°F on the day of application. In contrast, the sterol inhibitor tebuconazole (Lynx) did not produce any significant signs of turf damage, nor did any of the other fungicides tested. These observations are similar to those reported from Florida by Elliott (1995). In contrast, results of several years of fungicide evaluations on poa/bent greens indicates that Eagle is one of the safest products to use on cool season turf, while tebuconazole applications resulted in significant phytotoxicity to Poa annua.
  • With the possibility of Eagle induced phytotoxicity on bermudagrass greens indicated in trials from Florida and California, it is recommended that this product be reevaluated next summer in a variety of locations to further investigate this phenomenon.
  • Bermudagrass decline caused by Gaeumannomyces graminis var. graminis appears to be an increasing problem on greens. Background information on this disease appears at the end of this report.

Printable version of full report

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

Cooperator: Nancy Dickens, Sun City West, Palm Desert, CA

Sponsors: Bayer, Novartis, Rohm and Haas, Zeneca

 

Fungicides for Control of Anthracnose on Annual Bluegrass Greens

Summary: In a replicated field trial at San Diego Country Club, Chula Vista, CA, monthly applications of Heritage at 0.2 and 0.4 oz/1000 sq ft and Lynx at 1.5 oz/1000 sq ft provided excellent protection against anthracnose (Colletotrichum graminicola) attack on annual bluegrass greens when compared to Bayleton at 4.0 oz/1000 sq ft or the non-treated control plots. Less than acceptable performance of Bayleton may have been due to the monthly application interval (as opposed to a biweekly application interval).

Printable version of full report

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

Cooperator: Gary Dalton, San Diego Country

Club Sponsors:  David Ross, Zeneca and Gary Braness, Bayer

Progress in Understanding Rapid Blight of Cool Season Turf

Bottom line: Since 1995, when it was discovered in PACE’s laboratory to be a new pathogen of cool season turf, the identity of the disease that came to be known as rapid blight was hard to pin down, with some experts identifying it as a primitive chytridiomycete fungus and others as a protozoan. Success was finally achieved in March, 2003, when the laboratories of Dr. Mary Olsen and Dr. Robert Gilbertson confirmed that rapid blight is caused by an obscure microorganism that has features of both fungi and protozoans and is known as Labyrinthula. Until the discovery of its role in turf disease, Labyrinthula had been most frequently found infecting plants in marine environment such as seagrass, diatoms and algae. Further progress has been made in work by Drs. Bruce Martin, Mary Olsen and Dave Kopec in determing which turfgrass species are susceptible or tolerant to rapid blight infection. Additional field research has confirmed the activity of mancozeb (Fore, Protect) – either alone or in combination with trifloxystrobin (Compass) or pyraclostrobin (Insignia) for preventive control of this disease.

Printable version of full report PACE Insights 2003 Vol. 9 No. 3

by Larry J. Stowell, Ph.D. and Wendy Gelernter, Ph.D.

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