Golf Course Management

JAN 2018

Golf Course Management magazine is dedicated to advancing the golf course superintendent profession and helping GCSAA members achieve career success.

Issue link: http://gcmdigital.gcsaa.org/i/918033

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01.18 GOLF COURSE MANAGEMENT 123 CUTTING EDGE Teresa Carson Controlling Poa annua in creeping bentgrass fairways The objective of this research is to develop programs for annual bluegrass control in creeping bentgrass fairways using annual bluegrass weevil (ABW), plant growth regulators (PGR) and interseeding. Trials were initiated on mixed stands of annual bluegrass and creeping bentgrass with a history of ABW at three sites in New Jersey — Rutgers University Hort Farm No. 2 and two golf courses — April 20-27, 2017. Six treatments were tested: no insecticides = plots not treated with insecticides for ABW control; threshold control = plots treated with cyantraniliprole after unacceptable turfgrass quality was visible in most non-treated plots; complete control = plots treated with an industry standard insecticide program for ABW control; the three remaining programs were the same as the first three with the addition of the PGR paclobutrazol. Initial results suggest reductions in annual bluegrass quality caused by ABW larvae did not translate to season-long reductions in annual bluegrass cover. The paclobutrazol program reduced annual bluegrass cover at the Hort Farm No. 2 location. The combination of paclobutrazol and ABW threshold programs will be explored in more detail in 2018. The trial was terminated early at one of the golf courses because of the over-application of a herbicide, but that trial will be restarted in 2018. At the third location, the preventive insecticide program provided inconsistent results, and those data, therefore, need further analysis. — Katherine Diehl; Matthew T. Elmore, Ph.D.; Albrecht M. Koppenhöfer, Ph.D.; and James A. Murphy, Ph.D., Rutgers University, New Brunswick, N.J. Optimizing timing of snow mold fungicides Timing snow mold fungicide applica- tions in late fall can be difficult. Early appli- cations may break down before snow cover arrives, and late applications may leave turf unprotected and snow-covered for weeks or months. Late-fall conditions can also vary dramatically, so applying snow mold product on the same date each year can result in vari- able disease control. A three-year field study was initiated in 2015 to determine the opti - mal timing of snow mold fungicides at three locations in northern, central and southern Wisconsin. The northern site had the most consistent snow mold pressure during the winters of 2015-2016 and 2016-2017; the two treatment timings providing the most effec - tive snow mold control in both years were im- mediately before significant snowfall and two weeks before expected snowfall. Snow mold symptoms increased dramatically when appli - cations were made four weeks or more before expected snow cover. Heating degree days (HDD) in both years were between 125 and 150, using a base temperature of 50 F at two weeks before expected snowfall. This HDD range may provide a guideline for superinten - dents to use in timing snow mold fungicide applications, though further study and vali - dation is warranted before this range should be used. In addition to the above study, a growth chamber study investigating the up - take of propiconazole at various temperatures was conducted to determine whether cooler temperatures impede fungicide uptake. Though the results have not yet been fully analyzed, to date, plant uptake of propicon - azole does not appear to be significantly dif- ferent at temperatures of 62 F, 50 F, 43 F and 32 F. — Paul Koch, Ph.D., and Kurt Hockemeyer, University of Wisconsin-Madison Teresa Carson (tcarson@gcsaa.org) is GCM's science editor. These research projects were funded by a grant to GCSAA from the Environmental Institute for Golf. Photo by Paul Koch Photos by Matthew T. Elmore

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