Golf Course Management

FEB 2017

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/776985

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02.17 GOLF COURSE MANAGEMENT 87 CUTTING EDGE Teresa Carson Chlorothalonil + ferrous sulfate = dollar spot suppression Chlorothalonil, applied alone or in combi- nation with other fungicides, is often used for preventive or curative control of dollar spot on creeping bentgrass. Superintendents who rely on chlorothalonil may find that restrictions on its use prevent them from achieving desir - able levels of dollar spot control throughout the season. Ferrous sulfate applied at 1 pound product/1,000 square feet (48.8 kilograms/ hectare) has also been found to control dollar spot. The objective of this research was to de - termine whether combining ferrous sulfate and lower rates of chlorothalonil could result in ac - ceptable dollar spot control. The research was carried out in 2016 on a 007 creeping bent - grass putting green and L-93 creeping bent- grass fairway in Blacksburg, Va. Treatments included Daconil Weatherstik (chlorothalo - nil) applied at rates of 0, 1, 2, 3 and 4 fluid ounces/1,000 square feet (0, 2.28, 4.57, 6.86 and 9.16 kilograms a.i./hectare), with or with - out FeSO 4 (20% ferrous sulfate-heptahydrate) applied at 1 pound product/1,000 square feet. Using a conservative estimation method, chlo - rothalonil rates were reduced by (1.4 kilograms a.i./hectare) under heavy pressure (putting green), and 3.1 kilograms a.i./hectare under mild pressure (fairway). In related studies, fer - rous sulfate extended the longevity of chloro- thalonil by five days, and ferrous sulfate rates were cut in half (0.5 pound product/1,000 square feet) without sacrificing control. Stud - ies will continue in 2017 with reduced rates of ferrous sulfate and chlorothalonil . — Camden D. Shelton; David S. McCall, Ph.D. (dsmccall@vt.edu); Erik H. Ervin, Ph.D.; and Shawn D. Askew, Ph.D.; Vir - ginia Tech University, Blacksburg, Va. Winter foot traffic on a Poa annua green In the coastal Northwest (British Colum- bia, Washington, Oregon and Northern Cali- fornia), snowfall and freezing temperatures are minimal, and golf is often played year- round. In winter conditions, annual bluegrass (the dominant putting surface) has minimal traffic tolerance and recuperation. Our ob - jective was to document the effects of win- ter foot-traffic rates on an annual bluegrass green in the coastal Northwest. Field research was initiated in February 2014 on a USGA sand-based green with well-established an - nual bluegrass at the Oregon State University Lewis-Brown Horticulture Farm in Corvallis. Experimental design was a randomized com - plete block with four replications. Treatments were foot traffic equivalent to 0, 110, 220 and 440 rounds of golf per day compared with a control, which did not receive foot traffic. Turf color and quality data were rated on a scale of 1 to 9, where ≥6 was acceptable, from Jan. 7 to March 26, 2015, and Jan. 13 to April 8, 2016. The high rate of foot traffic (440 rounds per day) produced the greatest reduc - tion in turf quality and color. The control had the highest turf quality and color ratings dur - ing the study. Traffic at the high rate resulted in unacceptable values (<6) for turf qual - ity and color in February and March 2015, and for turf color in March 2016. Regression analysis showed that greens in the Corvallis area will experience reduced turf quality and color in the winter months if golf rounds ex - ceed 300 per week. — Alexander R. Kowalewski, Ph.D. (alec.kowalewski@oregonstate.edu); Conner Olsen; Brian McDonald; Clint Mattox; and Micah A. Gould, Oregon State University, Corvallis Editor's note: Earlier versions of t ese summa- ries were publis ed in t e 2015 and 2016 ASA- CSSA-SSSA Meeting Abstracts, ASA, CSSA and SSSA, Madison, Wis. Teresa Carson is GCM 's science editor. Photos by Camden D. Shelton 2 fluid ounces chlorothalonil 2 fluid ounces chlorothalonil + 1 pound FeSO 4 Photo by A. Kowalewski 440 rounds No traffic

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