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Tantallon Country Club in Fort Washington, Md., enjoys a diverse membership of locals and local celebrities. Situated on the banks of the Potomac River, Tantallon offers a view of the Washington monument and a reminder of just how close it is to the nation’s capitol.
Like most golf courses, this one isn’t without agronomic challenges. While the Potomac River adds to the unique experience of the course, it brings a few features that require significant management by the golf course superintendent and his crew.
“We are just a foot or two above the river on some of our fairways,” says golf course superintendent Todd Gribling. “Being that close to the water table creates an ideal environment where moisture-loving weeds like yellow nutsedge and green kyllinga tend to be problematic. We needed to find a pesticide that works better than the sedge products we had been using.”
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In late summer 2006, Gribling agreed to a trial on one of his creeping bentgrass fairways with Dismiss turf herbicide from FMC Professional Solutions. He staked off 1,000 square feet in the midst of a well-established stand of green kyllinga (Kyllinga brevifolia). Dismiss was applied at 4 ounces per acre on a sunny day in September, followed by a second application at the same rate 21 days later.
“Within four hours after treatment, I started to see activity on the kyllinga,” Gribling says. “Within two weeks, it was totally browned out.”
Because the kyllinga populations were so significant, Gribling knew he would have to deal with bare ground once control was achieved. To quickly establish a new stand of creeping bentgrass, Gribling relied on his agronomic experience to manage this area back into a playable fairway. As he worked to reestablish the turf in the test plot area, Gribling watched carefully for any detrimental effects of the treatment on the newly seeded bentgrass.
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“I didn’t see any lack of vigor, any turf discoloration, and I don’t think Dismiss affected germination either,” he says. (The label recommends reseeding one month after application.)
Tom Walsh, sales representative with UAP Professional Products, says he was impressed with the performance Dismiss but he wasn’t prepared for what he would find the following spring. As expected, green kyllinga came back with a vengeance, except in the area treated with Dismiss turf herbicide.
“We heard a couple of university researchers talk about nutlet control with Dismiss,” Walsh says. “We think what we’re seeing is a dramatically reduced population of kyllinga based on the soil activity of Dismiss.”
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Sulfentrazone, the active ingredient in Dismiss, is a PPO inhibitor that works by foliar contact. Additionally, Dismiss is adsorbed by roots and taken up by the plant through soil activity. Data from the University of Florida indicates soil treated with Dismiss significantly effects the germination of nutlets found in that soil.
Gribling has incorporated Dismiss into the treatment protocol as the standard for nutsedge control.
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The entire fairway was treated on May 14, 2007 with Dismiss at 4 ounces in 44 gallons of water per acre on a sunny, 75 F afternoon. Flat fan nozzles were used at 50 psi. The regular irrigation schedule was followed after application, however no rainfall had been measured between application date and May 25, 2007. The test plot area is clearly visible, as is the effect of the Dismiss treatment on surrounding sedges. The close-up view shows the activity on target weeds, including yellow nutsedge (Cyperus esculentus) and green kyllinga, as well as the turf tolerance to Dismiss exhibited by most creeping bentgrass varieties.