PACE Turf - Turfgrass Information Center

Diseases

Cyanobacteria (A.K.A. blue-green algae): WANTED for causing serious damage to turf

There are three widely shared misconceptions about the small, photosynthetic microbes that produce dark crusts and slime layers on putting green soils and foliage. The first is that all of these organisms are algae, when in fact many of them are cyanobacteria - microscopic organisms that are very different from true algae. The second misconception is that these organisms don't cause direct damage to turf, but are instead only secondary problems that result after turf has been stressed by disease, too much shade, poor drainage, or other factors. But in our diagnostic work we consistently find the opposite to be true. That is, cyanobacteria are frequently the direct cause of turf damage - resulting in mottled, yellowed and thinning turf on many cool season and warm season greens throughout the U.S. Thirdly, it is generally believed that algae or cyanobacteria are only problems in shady, wet areas. But we see many problems from sunny and relatively dry locations as well. From the standpoint of control, preliminary results indicate that although eradication is an unrealistic goal, several weekly treatments with chlorothalonil (Concorde, Daconil, Echo, Manicure, Thalonil) usually improves turfgrass quality by reducing cyanobacteria populations.

Full print version: PACE Insights 2000 Vol. 6 No. 8

First report of bermudagrass as a host for rapid blight

Summary: Rapid blight, a newly characterized disease of cool season turfgrass, can be problematic in the same locations for several years, even when fungicide applications are routinely made for its control. It is not known, however, how or where the pathogen survives. Samples taken from Arizona golf courses that overseed indicate that many other grasses, including warm season turfgrasses, are hosts for the rapid blight pathogen, Labyrinthula terrestris. In this study, we found that L. terrestris does indeed “over-summer” in the roots and stolons of bermudagrass, even in locations that have not been overseeded in several years, and even in locations that are regularly treated with fungicides targeted at controlling rapid blight. This suggests that bermudagrass serves as a large, symptomless reservoir of rapid blight inoculum, an observation that helps explain why rapid blight is such a perpetual threat in overseeded turfgrass systems.

Full print version of report (108Kb)

Investigators: Mary W. Olsen and Michele J. Kohout, University of Arizona, Department of Plant Sciences

PACE Members Featured in Rapid Blight Article

PACE Members Featured in Rapid Blight Article: July, 2005

We are proud to announce that this month’s feature story on the American Phytopathological Society’s web page Rapid blight: a new plant disease. The article, a collaborative effort among researchers from PACE, Clemson University and the University of Arizona, highlights the progress made over the past 10 years in identifying this extremely interesting new pathogen, and in developing management plans for its control. Also highlighted is the critical role that superintendents played in the discovery of the disease and in the evolution of strategies for its management.

Superintendents highlighted in the article include:

  • David Zahrte, Santa Ana Country Club, California
  • Kurt Desiderio, Saticoy Country Club, California
  • Mick Twito, Estrella Mountain Ranch Golf Club, Arizona
  • Tommy Witt, when he was at Cassique Golf Course, South Carolinia

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