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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114 GOLF COURSE MANAGEMENT 01.18 Using PGRs in golf course roughs Using PGRs to reduce rough height and mowing costs can save time and money for the golf course maintenance team. Golf course superintendents often receive criticism about the condition of what some might consider low-maintenance features, such as roughs and out-of-play areas. These make up roughly 60% of the area on most golf courses (1), and as much as 20% of a golf course budget can be spent on their mainte - nance. Healthy turf is desirable in roughs, as a thick turf stand provides competition for weeds, preventing their growth. However, mowing high rough produces excess clippings — which can be unsightly and difficult to re - move — and can often result in scalping (3). Golf balls that enter deep rough may be lost or settle in an unplayable lie. Other problems associated with rough maintenance are the presence of obstacles such as trees or shrubs or hidden objects such as rocks and sticks — all of which are hazard - ous to mowers. Rough maintenance ideally commences early in the morning before golf - ers arrive on the course, but heavy dew at that time of day can make mowing and clipping removal even more laborious. Because roughs typically make up the larg - est area of the course and because that area can be hazardous to mow, maintaining them re - quires a lot of manpower, equipment and fuel. Some facilities are looking to incorporate low- maintenance rough areas, but this is not prac - tical for every course. Plant growth regulators Plant growth regulators and retardants (PGRs) are a group of chemicals used in the regulation or retardation of plant growth. PGRs have varied modes of action. For ex - ample, trinexapac-ethyl, one of the most com- monly used PGRs in the turfgrass industry (4), is a gibberellic acid inhibitor. Gibberellic acid is required in cell elongation, so trinexa - pac-ethyl prevents grass cell elongation and thus maintains the grass at a lower height (5). In addition, trinexapac-ethyl causes chloro - phyll to be denser in regulated leaves, giving plants a deeper green color, increasing turf - grass quality, and possibly improving stress tolerance. Although PGRs have varied modes of action, they share the ability to reduce turf - grass growth. Herbicides at less-than-lethal application rates can be used like PGRs to suppress plant growth. Although numerous modes of action exist, many herbicides used in this study in - hibit turfgrass growth and development by in- terrupting synthesis of amino acids (2), which are the building blocks for protein develop - ment. When using a herbicide in this way, pre- cise product application is required, because too much active ingredient may damage the turf, and too little will not provide sufficient growth suppression. Materials and methods We investigated the impact of an array of PGRs and herbicides on the control of rough turf height at the Walker Golf Course, Clem - son, S.C. The study was repeated over two years in two separate but adjacent locations, each containing a mixture of Tifway (Cyn - odon traansvalensis × C. dactylon) and com- mon bermudagrass (C. dactylon). The study included 11 treatments of PGRs and herbi - cides at various rates, including Primo, Pla- teau, Anuew, Cutless, Legacy, Musketeer, Roundup and Finale (Table 1). The study was in a randomized complete block design, and treatments were applied using a carbon-diox - ide backpack sprayer calibrated at 20 gallons/ acre (187 gallons/hectare) using 8004 flat-fan spray nozzles. Treatments were applied at the beginning of three summer months, following mowing to 2.5 inches (6.4 cm) with clippings removed. After 30 days, data was collected, and all plots were mowed back to 2.5 inches. Turf phyto - toxicity data was collected weekly, after treat- Philip Brown, M.S. Don Garrett, CGCS Bert McCarty, Ph.D.

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