While superintendents continue to battle dollar spot on their golf courses, researchers are busily looking for improved methods to combat this foe. Fortunately, it doesn’t appear to be a shifting target.
“I don’t think we are seeing anything new in how the disease presents in the field,” says Michael Boehm, vice provost and professor in The Ohio State University’s Department of Pathology. “It is still there and is – at least in the Midwest – one of, if not the major disease we face.”
According to Boehm, work on the disease has ranged from the very practical/applied to the basic-science level.
“Work in our program at Ohio State covers the water front from applied work with screening fungicides – both existing and new ones – to exploring how the fungus causes disease,” he says.
If you believe there is strength in numbers, researchers are flexing their muscles. During the past 18 months, a group of turfgrass pathologists from across the United States has decided to join forces and submit a proposal for a new multi-state USDA-sponsored program related to dollar spot. North Carolina State University’s Lane Tredway is providing leadership on this project – pulling the team together.
The project is entitled ‘NCDC220: Biology, Etiology, and Management of dollar spot in Turfgrasses’: http://nimss.umd.edu/homepages/home.cfm?trackID=12176.
If dollar spot isn’t changing, are researchers recommending adjustments in the way superintendents go about treating the disease? Boehm deferred to colleague Joseph Rimelspach.
“No new earth-shattering thing,” says Boehm’s colleague Joseph Rimelspach, while stressing early, pre-symptom applications are crucial in suppressing the organism that causes the disease. Reduce the amount of inoculum and delay onset of dollar spot.
“Superintendents must know what fungicides work on dollar spot at their golf courses,” he says, adding that if the DMI family works, Tourney “is an excellent product.”
That’s on a case-by-case basis, of course, and researchers have seen high incidents of resistance on golf courses to older systemic products.
Of utmost importance, according to Rimelspach, especially if superintendents saw scarring from dollar spot in 2010, is to grow grass immediately on those affected areas this spring. If areas have not recovered well and are not protected, more - and more challenging - dollar spot can be predicted for this year.
Last summer’s difficult conditions have not changed Boehm’s recommendations for superintendents in 2011.
“I will say that it is critical for superintendents to always try to grow as ‘healthy’ and stress-free turf as possible,” he says. “Always easier said than done, but it’s essential to pay attention to the basic agronomic practices that ensure healthy turfgrass: core aerification, use of a balanced fertility program, proper mowing practices with sharp blades/reels, proper diagnosis of problems, judicious use of fungicides and when used, paying attention to rates and proper rotation of active ingredients to reduce the development of fungicide resistance.”
Likewise, cultural changes are not imminent, according to Boehm.
“I’m not sure there are any radical changes in how superintendents should, or will, manage dollar spot,” he says. “In fact, a continued commitment to an integrated management philosophy/approach, built upon a solid agronomic program that includes maintaining a balanced fertility program, reducing prolonged leaf wetness, dew whipping/polling of greens, dragging of fairways, etc., is key and likely will go a long way to helping reduce the amount and intensity of dollar spot.
Ohio State’s factsheet on dollar spot can be found at http://ohioline.osu.edu/hyg-fact/3000/pdf/3075.pdf.
As winter releases its grip over quite a bit of the country, leaving behind a season that will be remembered for unusually heavy ice and snow, many superintendents are just now seeing what has been left behind and possibly what is in store for spring.
“Truth of the matter is that it is difficult to know what impact this winter’s weather will have on dollar spot,” Boehm says. “If a superintendent got his preventive snow mold treatment down prior to snow cover and he used a fungicide that is also effective against dollar spot, one might speculate, based on some of our research over the past decade, that they may see less dollar spot pressure.
“Likewise, if a superintendent makes early springtime applications for snow mold or leaf spot or has adopted an early spring dollar spot fungicide treatment program, then they may also see less intense dollar spot pressure during the 2011 season,” he adds. “Based on my experience with Ohio superintendents over the years, most are going to roll with the punches Mother Nature tosses their way and manage their turf in as healthy a manner as possible. Hopefully, the soil water levels recharge themselves, the spring isn’t too wet, and summer is moderate. One can hope anyway.”
Although not directly related to dollar spot, a new resource is now available to turfgrass managers. “A must have, in my opinion, for every superintendent,” says Boehm. Professor Rick Latin at Purdue recently published a book entitled “A Practical Guide to Turfgrass Fungicides.” The book is currently available by APS Press - http://www.apsnet.org/apsstore/shopapspress/Pages/43924.aspx. “This is a great book that provides a great deal of useful information for golf course superintendents,” added Boehm.
