Columbus, Ohio – Turfgrass research being conducted at The Ohio State University was on display at the 2005 OSU/OTF Turfgrass Research Field Day Aug. 17. The Ohio Turfgrass Foundation Research and Education Facility on the OSU campus was the site for golf course superintendents and green industry professionals to learn about the latest developments in turfgrass management.
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Ed McCoy, Ph.D., has been looking into the role wetting agents play in irrigation water conservation. On a plot mowed at fairway height, with a slope of 4 percent, the control area receives no wetting agent treatment, while the other plots receive weekly applications of Aquatrols’ ACA 1848 at either 12 or 24 ounces per acre.
Results from 2004 showed, during dry periods where supplemental irrigation was used, soil water suction was less for both plots using wetting agents than for the control plot. According to the study, this suggests fewer irrigation events would be needed on turf receiving a wetting agent. Conversely, during wet periods, researchers saw 20 percent less stormwater runoff from the treated plots. There were no apparent differences between the 12- and 24-ounce application rates for water status or runoff measurements.
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Nitrogen and dollar spot
Research associate Deb Holdren from the Ohio State department of horticulture and crop sciences displayed work being done by her and associate professor John Street about the effect of nitrogen source, rate, timing and application method on creeping bentgrass quality and dollar spot incidence.
The plot of Lopez creeping bentgrass was sectioned off and treated weekly and biweekly with different levels of nitrogen. There also was an untreated check area.
Overall, the research shows the best foliar treatment for dollar spot suppression was 0.25 pounds of nitrogen per thousand square feet weekly for all foliar sources. Additionally, turfgrass color was better as the total monthly nitrogen rate increased from 0.7 to 1.0 pounds N/M. Also, color response from granular treatments was slower than for foliar treatments by one to two weeks.
Controlling annual bluegrass
Street displayed research conducted by Holdren and himself about controlling annual bluegrass in creeping bentgrass with the herbicide Velocity (bispyribac-sodium). They looked at treating at higher rates (two and three applications of 30 grams at 14-day intervals) and lower rates (four applications of 10 grams at seven-day intervals).
Preliminary research suggests a total of 60 to 90 grams (active ingredient per acre) of Velocity herbicide are required to achieve desired effects against annual bluegrass. Some temporary discoloration of creeping bentgrass was reported.
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Michael Boehm, an associate professor in OSU’s department of plant pathology is studying the impact of fall and spring fungicide applications on dollar spot. The impact of the application on the following season was the main objective.
According to the study, results have shown that fall and spring fungicide treatments can significantly delay the initiation and reduce the severity of dollar spot outbreaks in the growing season. Weather conditions in the spring and fall influenced the effectiveness of the fungicide applications.
The most effective combat against dollar spot severity the following spring came with three fall applications of propiconazole and chlorothalonil. One application was better than none, but not as effective as three.
Boehm and his associates also found there’s a window of opportunity for making preventive fall or spring fungicide applications. According to the study, a single fall application of propiconazole or chlorothalonil on Oct. 10 or Oct. 24, 2003 significantly reduced dollar spot severity the following season. However, fungicide applications made early in the fall or after Oct. 24, 2003 didn’t reduce dollar spot severity in May and June 2004.
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Controlling brown patch
Joseph Rimelspach, program specialist with the department of plant pathology, is evaluating the use of fungicides for the control of brown patch in creeping bentgrass.
Conditions during the test were seasonal for May through July. Temperatures ranged from average highs and lows of 76.8 F and 55.7 F in May to 81.2 F and 62.8 F in July. Rainfall, in inches, was 7.1, 3.5 and 11.3 through the study.
Insignia (20 WG at 0.9 ounces per square feet) and Spectro (90 WG at 4.0 ounces per 1,000 square feet) provided complete control of brown patch at eight days after the initial application and throughout the evaluation. Insignia had an application interval of 28 days, while Spectro had an application interval of 14 days.
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Jia Yan, a graduate student in the department of horticulture and crop science, displayed the research she’s done with professor Karl Danneberger and associate professor David Gardner on transgenic creeping bentgrass under various light conditions. Wild type creeping bentgrass, Roundup Ready creeping bentgrass and shade resistant transgenic creeping bentgrass were planted under full sun, artificial shade and tree canopy.
According to the research, data showed that: Reduction in light intensity and quality would greatly affect turf plants growth; gene transformed turf plants showed a range of responses to shade stress; and some transgenic lines showed desirable phenotype under full sun and shade conditions.
The 2005 OTF Conference and Show is scheduled for Dec. 6 through 8 at the Greater Columbus (Ohio) Convention Center. For more information, call 888-683-3445, e-mail info@ohioturfgrass.org or visit www.ohioturfgrass.org.
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