Golf Course Management

DEC 2018

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

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62 GOLF COURSE MANAGEMENT 12.18 ization rate and thermal tolerance range that would be most conducive to reducing infes tation while maintaining optimal turf growth and quality. Scalping and frequent close mowing are suggested as methods of removing infested terminals. A study published by University of Florida Extension (1) has suggested that ber mudagrass mite damage was reduced by 50%, 28 days after the damaged turf was scalped in late spring. However, damage was increased by 500%, 36 days after the turf was scalped in early spring. e results suggest that the effec tiveness of scalping as a management method is dependent on season, but since no unscalped check was included, we could not confidently verify that the changes in mite damage were due to the scalping treatment or seasonal dif ferences in mite activity. Our observations corroborated Johnson's observations that bermudagrass mites can be spread by clippings (5). e mites leave the drying clippings and move to nearby turf. erefore, clippings from scalping operations should be collected and discarded, and mow ing equipment used on infested turf should be cleaned and washed, at designated areas far from the desirable turf. Research on chemical control Research to identify effective pesticides began as soon as the bermudagrass mite was found in the United States (10). e senior author also conducted similar evaluations in 2009 2010 (2). Several insecticides were found to be highly or moderately effective, but some of these chemicals are no longer available, or their use is severely restricted on golf course turf. For example, diazinon and dicofol are no longer available to the turf industry in the United States, and certain chlorpyrifos prod ucts (such as Dursban Pro, Dow) are not reg istered for use on golf course turf. Several insecticides are currently registered for bermudagrass mite control on golf courses, including abamectin (Divanem, Syngenta), azadirachtin (for example, Azatrol, Gordon's), bifenthrin (for example, Broadcide GC, Con trol Solutions), chlorpyrifos (for example, Chlorpyrifos SPC, Nufarm), lambda cyhalo thrin (for example, Scimitar GC, Syngenta) and zeta cypermethrin (for example, Triple Crown, FMC). In addition, cypermethrin (for example, Demon WP, Syngenta), delta methrin (for example, Suspend SC, Bayer) and esfenvalerate (for example, Onslaught, MGK) are registered for control of bermu dagrass mite in athletic fields, lawns and other turf areas. Consult insecticide labels for use sites, instructions and restrictions. With the hope of identifying insecticides that could be used to replace unavailable or restricted, but effective, insecticides, the se nior author conducted a series of experiments in 2009 2010 to evaluate the efficacy of 26 insecticides and miticides for bermudagrass mite control (2). Abamectin stood out as one of the most promising products. Further test ing of the efficacy of abamectin in several golf courses in South Carolina has supported the registration of Divanem (8% abamectin) for bermudagrass mite management. Divanem is currently the only product that showed consistent improvement in the quality of mite infested golf course turf in my studies. Similarly, Divanem was more effective than Triple Crown (a pre mix product containing zeta cypermethrin, bifenthrin and imidaclo prid; FMC) and a control using water in a trial conducted in Florida (1). e same researchers (1) also found no difference in mite damage in scalped and unscalped turf treated with Di vanem. e senior author conducted a series of experiments in 2014 2016 (sponsored by Syn genta) to determine the best application tim ing of Divanem. e hypothesis was that four biweekly applications initiated in April (soon after green up) reduced the bermudagrass mite population early in its population growth and thus would be more effective in reducing the number of witches' brooms than applica tions initiated in June (when damage has al ready occurred). e results from this study were inconsistent. April applications of Di vanem were more effective than June applica tions in two years, but June applications were more effective in one year. is study will be repeated in the coming years with a different sampling method (including direct assessment of mite abundance) to identify the best appli cation timing and frequency. Miticides used for bermudagrass mite con trol should be applied as sprays repeated every two weeks. e senior author included a sur factant, Dyne Amic (methyl esters of C16 C18 fatty acids, polyalkyleneoxide modified polydimethylsiloxane, and alkylphenol ethox ylate, Helena), in all his studies. We suggest that a surfactant be included in all spray solu tions to improve penetration through the gaps between stems and leaf sheaths, where the mites feed. Future research In the program at Clemson, we will con tinue to evaluate and select effective insecti cides for bermudagrass mite control. In Aus tralia, clofentazine, propargite, abamectin, bifenazate, etoxazole and spirodiclofen have been reported to be effective at reducing in festations by bermudagrass mites and Dolicho tetranychus species (8). In the United States, clofentazine is available as Notavo (OHP) (formerly, Applause); bifenazate is Floramite (OHP); and etoxazole is TetraSan 5 WDG (NuFarm). ese miticides are currently not registered for use on turf. We will also evalu ate other miticides with demonstrated efficacy against eriophyid mites in ornamental plant or field crop systems. ese studies are the first step in gathering efficacy data to persuade pesticide manufacturers to undertake further evaluation and seek registrations for use on turf. Insecticides are not the only tools that will be evaluated. As we have learned over the past nine years, a management program against the bermudagrass mite can be successful only if it is multi pronged and considers all aspects of turfgrass management practices. In other words, an integrated management approach will be the best way forward. Over the next four years, we will be con ducting a series of laboratory and field studies with the goal of improving and integrating ber mudagrass mite management. e first project will include studies to better understand the life cycle and pest status of the bermudagrass mite. We want to know what is fact and what is fiction. What are its developmental time, reproductive potential and survivorship rate? When, where and in which life stage does it

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