Golf Course Management

MAR 2017

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

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03.17 GOLF COURSE MANAGEMENT 79 CUTTING EDGE Teresa Carson Influence of spray rate volume and surfactants on large patch control Large patch (R izoctonia solani), which af- fects the stems and sheaths of Japanese lawn- grass (Zoysia japonica), is difficult to control using traditional fungicide sprays. Applying fungicides so that they are deposited lower in the plant canopy, where infection occurs, could improve control of large patch. Field and greenhouse experiments were conducted in 2015 and 2016 to test the efficacy of fun - gicides applied at various spray rate volumes with or without surfactant additives. The first experiment evaluated azoxystrobin at high labeled rates and applied at four differ - ent spray rate volumes (0.23, 0.9, 1.8 and 3.6 gallons/1,000 square feet). The second experi - ment evaluated azoxystrobin, flutolanil and tebuconazole (applied at high labeled rates) applied with or without an organosilicone sur - factant (0.25% v/v). Treatments were made twice in the fall and once the following spring. Digital image analysis was used to determine the percentage of diseased turf. These experi - ments were also conducted under greenhouse conditions. Spray rate volume had a greater effect on large patch control than the use of surfactant additives in this research. On most rating dates, fungicides applied in higher spray rate volumes (≥ 1.8 gallons/1,000 square feet) resulted in greater large patch control than those applied in lower spray rate volumes. In - creased disease control at higher spray rate vol- umes may result from the application of more fungicide at the site of pathogen infection. Further research on the combination of high spray rate volumes and surfactant additives is warranted. — Jesse J Benelli, Ph.D. (jbenelli@, Chicago District Golf Association; and Brandon J. Horvath, Ph.D., University of Tennessee- Knoxville Irrigation sensors for lawns Professional turf managers use rain sensors (RS) and soil moisture sensors (SMS) to reg - ulate automated irrigation applications, but how about homeowners? New SMS are be - coming more "homeowner-friendly" in terms of their installation and calibration methods as well as their purchasing cost. The objectives of a field study at the University of Arkansas were to determine how irrigation sensors af - fect turf quality and whether they effectively reduce water consumption. This study was conducted on bermudagrass [Cynodon dacty - lon (L.)] turf, with scheduled irrigation apply- ing 0.5 inch (1.3 cm) of water twice a week. The five irrigation treatments consisted of two SMS models, two RS models and a control (no sensor). Rain sensors communicated with the irrigation timer to bypass irrigation fol - lowing significant rainfall, and SMS provided the timer a real-time estimate of volumet - ric water content in the turfgrass root zone, which then bypassed scheduled irrigation if the moisture content was above the SMS- calibrated threshold. Over a 17-week period, RS reduced water use by 20%, and SMS re- duced water use by 65%, yielding significant savings. Digital image analysis showed that all treatments resulted in acceptable turf quality. Moreover, significant reductions in irrigation costs were observed, with an immediate po - tential return on investment for RS (+$75) and SMS (+$175) within the trial period for a 0.25-acre (0.1-hectare) lawn in Fayetteville, Ark. SMS may significantly reduce water use and associated fees while simultaneously pro - viding acceptable turf quality for homeown- ers. — Daniel Sandor (; Douglas E. Karcher, Ph.D.; and Michael D. Richardson, Ph.D., University of Arkansas, Fayetteville Teresa Carson is GCM 's science editor. Photo by Jesse Benelli Photo by Douglas Karcher

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