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Seashore paspalum decline
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Along with new turf cultivars come new diseases, and seashore paspalum (Paspalum vaginatum) is not immune. Mike Healy, Ph.D., a turf consultant in Elberta, Ala., recently reported that his organization had diagnosed its first case of seashore paspalum decline on a golf course in Florida. But, as Healy points out in his newsletter (www.sportsturfdiagnostics.com), the disease has been seen before.
W.C. Elmore, M.D. Gooch and C.M. Stiles, Ph.D., from the University of Florida published the first report of seashore paspalum decline found in the U.S. in the December 2002 issue of the journal Plant Disease. A turf sample taken from a home lawn in Hernando County, Fla., had “rotted roots and stolons,” and patches of the lawn turf were dying.
The only fungal plant pathogen found in the sample was Gaeumannomyces graminis var. graminis, the fungus responsible for take-all root rot disease in St. Augustinegrass. The authors of the report, therefore, named the disease take-all root rot in seashore paspalum. However, the same plant pathogen also causes a disease in bermudagrass often referred to as “decline.” The fungus was discovered more recently in kikuyugrass (described by Frank Wong, Ph.D.; Wendy Gelernter, Ph.D.; and Larry Stowell, Ph.D.), leading to a diagnosis of kikuyugrass decline.
Gaeumannomyces graminis var. graminis is an ectotrophic root-infecting fungus (also known as an ERI fungus). The fungus attacks turfgrass roots and shoots. Dark lesions appear on the base of turf leaves, and dark brown runner hyphae attack the roots. Mycelia with lobed hypophodia characteristic of other diseases caused by G. graminis are also seen in seashore paspalum decline.
Because the fungus first attacks underground, disease symptoms will not appear on the surface until several weeks after the initial infestation. As with bermudagrass decline, surface symptoms include yellowing or bleached patches of grass that range from a few inches to 2 feet in diameter. Left untreated, the affected grass eventually thins out and dies.
What can be done to treat seashore paspalum decline? Because superintendents and scientists have had little experience with seashore paspalum decline, researchers suggest that superintendents follow the same management and control practices used to treat bermudagrass decline. These diseases are tenacious once they are established, so preventive measures are best.
Gelernter and Stowell (www.paceturf.org) caution that the following conditions can stress turf and thus encourage the development of diseases caused by Gaeumannomyces: low mowing heights, traffic, extremes in moisture, poor drainage, temperature extremes, reduced solar radiation, poor fertility and soils with low manganese.
Mowing greens higher than 0.1875 inch and fairways higher than 0.5 inch while providing conditions for healthy root growth may prevent appearance of the disease on the turf’s surface. Because there are few, if any, fungicides registered for control of paspalum decline, these cultural practices are particularly important.
In addition, Healy cautions against what he calls “severe mechanical disturbances” such as verticutting or core removal, which increase the likelihood of seashore paspalum decline. If the disease is present in the soil, surface symptoms will often appear within two weeks of such maintenance practices. However, Gelernter and Stowell recommend promoting root health with deep-tine aeration and sand topdressing in the spring.
A $1 million donation from The Fertilizer Institute on behalf of the Nutrients for Life Foundation will fund the Smithsonian Institutions’ exhibition about soils at its National Museum of Natural History in Washington, D.C. The Fertilizer Institute and Nutrients for Life are the lead sponsors of the exhibit, which was scheduled to open in July. The 5,000-square-foot soils exhibit, developed by the Smithsonian in partnership with the Soil Science Society of America, is designed to increase public awareness about the importance of soils in the world and to human life. The exhibit features interactive games, videos and other activities to demonstrate the vital link between soil and health of mankind and the environment. The State University of New York Delhi’s turfgrass program continues to receive support from the golf management industry, the latest donation coming from E/T Equipment Co., Croton-On-Hudson, N.Y., which recently gave a JD 3215-A fairway mower to enhance education opportunities the program can offer. SUNY Delhi offers a hands-on four-year degree in golf course management with its own golf course for laboratory instruction. |
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