Golf Course Management

OCT 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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10.18 GOLF COURSE MANAGEMENT 71 approximately 6 inches (15 cm) long and ¾ inch (2 cm) in diameter. Soil cores were 4 to 5 inches (10 to 12.7 cm) long and roughly the same diameter as a sleeve. Each core, along with its dead surface veg - etation, was installed in a sleeve. After a soil core was inserted carefully into the sleeve, four adult annual bluegrass weevils were placed on the soil surface within each sleeve (Figure 3, top). Sleeves were crimped at the top, closed with a staple and then inserted into the origi - nal soil core hole and positioned so the weevils were flush with the surrounding soil surface and nested within the surrounding vegetation (Figure 3, bottom). Five sleeves were installed in each of the 30 plots for a total of 150 weevil sleeves (600 weevils). All weevils used for the study were col - lected on site from a nearby rough or were heat-extracted from blue spruce needle litter using Berlese funnels. Weevils were kept alive on moist filter paper until being added to the sleeves. Soil temperature tracking To evaluate the impact of the vegetation management practices, we also installed soil temperature loggers (iButtonLink) in a single replicate block at the Robert Trent Jones GC site. iButton loggers were placed in 50 ml plas - tic tubes on top of a bed of oven-dried clay. e plastic tubes were capped and sealed with parafilm and then inserted into the soil so that the iButton was positioned at the soil surface and embedded directly in the surface vegeta - tion of the plot. Two loggers were installed per plot and, once deployed, were allowed to col - lect data continuously at 2-hour intervals from December 2016 through March 2017. Spring sampling All weevil sleeves were harvested at the Robert Trent Jones GC site on April 4, 2017. Each sleeve was carefully removed from the ground and transported to the lab. In the lab, each sleeve was cut open, and soil was sorted to locate each of the four weevils. Weevils were recorded as live, dead or missing. In addition, at both golf courses, five soil cores — each 2.5 inches (6.35 cm) in diameter × 2.5 inches deep — were harvested from each plot and placed on heat extractors at the New York State Agri - cultural Experiment Station in Geneva, N.Y., to extract any naturally overwintering annual bluegrass weevil adults. Results When confined to the mesh sleeves at the soil surface, average annual bluegrass weevil winter survival was approximately 48% and ranged from a low of 40% to a high of 60%. Survival was lowest in untreated control plots and plots where vegetation was removed fol - lowing mowing alone or mowing, vegetation removal plus herbicide application (Figure 4). In contrast, survival was greatest (~60%) where vegetation was mowed or killed by her - bicide but left in the field. Unfortunately, in spring 2017, the recovery of naturally over - wintering weevils via heat extraction from soil cores was too low to compare their survival with that of weevils in mesh sleeves. Soil temperature data suggested that soil microclimate is influenced considerably by vegetation management practices in golf course natural areas. For instance, soil tem - perature from Jan. 11 to Jan. 24 ranged from a low of approximately 14 F (-10 C) to a high of 68 F (20 C), and we observed less fluc - tuation in unmanaged control plots or plots receiving only herbicide than in plots where vegetation was mowed; mowed and removed; or treated with herbicide, mowed and re - moved (Figure 5). Discussion e results of this project suggest that management practices employed in golf course natural areas have the potential to influence the success of overwintering for annual blue - grass weevils. Specifically, mowing or treating overwintering areas with herbicide has no im - pact on annual bluegrass weevil overwintering as long as vegetation is removed from the area. If, however, mowed or herbicide-killed vegeta - tion is not removed, weevils may be better able to survive winter conditions at the soil surface. e findings suggest that the differences observed in weevil winter mortality may be partly related to variation in soil microclimate Annual bluegrass weevil survival Figure 4. Annual bluegrass weevil overwintering survival differed under various natural area management treatments in Ithaca, N.Y. (from left): a management-free control; mow and leave clippings; mow and remove clippings; herbicide only; apply herbicide, mow and remove clippings. 70 60 50 40 30 20 10 0 % Alive weevils Control Mow Mow Herbicide Herbicide Remove Mow Remove

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