Golf Course Management

FEB 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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02.18 GOLF COURSE MANAGEMENT 81 program may eventually require subtle adjust- ments in existing fertilization and irrigation programs to compensate for the increasingly infertile and droughty mat (sand + thatch) layer that develops over time. Moreover, the beneficial effect of sand topdressing has been shown to hold true even under conditions of intense foot traffic (that is, the equivalent of 200 rounds per day with golf shoes fitted with soft spikes; 25). A study of sand incorporation techniques (stiff- and soft-bristled brushes, vibratory rolling, and light irrigation) and sand particle shape (round vs. sub-angular) indicated that these factors had little effect on disease severity (19). All of these findings further substantiate that wounding does not influence anthracnose on annual bluegrass turf. Combining BMPs Recent studies have examined the response of anthracnose to combinations of practices to gain a better understanding of their relative importance in a BMP program. A study of nitrogen fertilization, mowing height and sand topdressing indicated that the combination of all three best practices (in - creased nitrogen, higher mowing and greater topdressing) was the most effective manage- ment regime for suppressing anthracnose (12). And, in two of the three years of the study with moderate epidemics, this best manage - ment regime suppressed anthracnose to levels that would be acceptable at many golf courses without the use of fungicides. However, the playability of putting surfaces managed with this best management regime may not be ac - ceptable at some golf courses because green speed (Stimpmeter ball roll distance) often dropped below the 9.5- to 10.5-foot range under higher mowing (0.125 inch; 3.175 mm), especially when that practice was com - bined with greater nitrogen fertilization. Research indicated that only one compro - mise among the three BMPs (lower mowing height to 0.090 inch; 2.286 mm) was needed to achieve acceptable playing conditions (≥10 feet; 3 meters) 91% to 96% of the time (12). Fortunately, lowering the mowing height only presented a modest risk for increasing disease severity compared with decreasing nitrogen fertilization. It is also important to note that under lower mowing (0.090 inch), ball roll distance was much less influenced by greater nitrogen fertilization. Although greater sand topdressing was effective in lowering disease under both ni - trogen fertilization levels, the reduction in disease was more dramatic under lower nitro - gen fertilization (2 pounds/1,000 square feet; 9.7 grams/square meter per year). Similarly, greater topdressing reduced disease under both mowing heights, but the reduction in disease was more substantial under the lower (0.090-inch) mowing height. Thus, golf turf managers should recognize that routine top - dressing is most beneficial under lower mow- ing and lower nitrogen fertilization. Moreover, when adjustments in best practices for an - thracnose management are needed to enhance playability (ball roll), superintendents should first consider lowering the mowing height to provide that enhancement without concern of greatly increasing the risk for anthracnose, as long as greater nitrogen and routine topdress - ing practices are also employed. Fungicide efficacy A study of the effects of mowing height and nitrogen fertility on fungicide program - ming for anthracnose indicated that these BMPs improve fungicide efficacy and make a reduction in fungicide inputs feasible (10). Ac - ceptable disease control was achieved with re- Ball roll distance measurements were taken from research plots to determine whether management regimes would affect playability of the putting surface. Photo by Youssef Elkhateeb

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