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.

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116 GOLF COURSE MANAGEMENT 01.18 The active ingredient imazapic was a com- ponent of three treatments (Plateau, Plateau + Primo, and Journey), and it also caused phyto - toxicity, but at different times than Finale. By two weeks after the initial application, applica - tion of products containing imazapic had re- sulted in about 20% phytotoxicity, which in- creased to approximately 25% at three weeks after initial application (Figure 2). Damage was still visible at four weeks after applica - tion, and all phytotoxicity ratings on all dates were within the maximum damage threshold (30%). Imazapic is an acetolactate synthase (ALS) inhibitor herbicide, and therefore some degree of plant damage can be expected. Several other treatments caused minor levels of phytotoxicity, but this was not con - sistent between replications and was usually short-lived and within acceptable levels. By the end of each monthly study cycle, all plots had fully recovered from phytotoxicity dam - age (Figure 3). Turf ei Plots treated with Roundup and Finale showed only minor differences in turf height compared with the untreated plots (Fig - ure 4). In the case of Finale, its ammonium content likely causes a flush of growth. The simultaneous lack of phytotoxicity and re - duced growth in the Roundup-treated plots suggest that a higher concentration of the herbicide may be required to achieve the desired results. This should be investigated with future research. Plots treated with products containing imazapic had low turf height, but this could be attributed to the phytotoxicity damage caused by the product. Therefore, the benefits of low turf height should be weighed against the drawbacks of visible damage. The turf heights of Primo-treated plots were consistently among the lowest in the study, with little to no observable phytotoxic - ity. Primo-treated plots also suffered very little scalping after mowing compared with several other treatments. The low rate of Legacy, 18 fluid ounces/ acre (1.31 liters/hectare), produced turf height that was statistically similar to that of the un - treated plots. Increasing the rate of Legacy to 30 fluid ounces/acre (2.19 liters/hectare) re - sulted in excellent turf height control. Figure 1. Distinct phytotoxicity symptoms are seen in bermudagrass rough one week after initial application of Finale at 16 ounces/acre; plots treated with Journey and Primo do not show phytotoxicity. Photos by Philip Brown Figure 2. Three weeks after initial application, bermudagrass rough plots treated with Journey (imazapic) show phyto - toxicity, whereas plots treated with Finale and Primo do not. The Finale plot had recovered from initial phytotoxicity (see Figure 1). Figure 3. Four weeks after initial application of Finale, Journey and Primo, all the treated plots in the bermudagrass rough had recovered from phytotoxicity. The Primo plot has visibly lower turf height and darker green color. Finale (16 oz/acre) Journey (11 oz/acre) Primo (22 oz/acre) Finale (16 oz/acre) Journey (11 oz/acre) Primo (22 oz/acre) Finale (16 oz/acre) Journey (11 oz/acre) Primo (22 oz/acre)

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