Golf Course Management

JUL 2017

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 07.17 influence of predetermined variables (treat- ments). Every month during the experiment, a soil probe with a 4-inch diameter was used to collect 10 soil cores at random from the monitored area of each fairway. The collected soil cores were examined in the laboratory for larvae and/or pupae. A minimal number of larvae/pupae specimens were collected during this experiment, similar to previously docu - mented results in the literature. No mean- ingful data could be derived from the larval populations, and therefore no larval data are presented in this report. Results and discussion The number of billbug adults recovered from the pitfall traps varied significantly be - tween the two sites. In 2015, a total of 876 billbugs were recovered at CCC, which was more than five times the number found at CCMO (Figure 4). In 2016, a total of 158 billbugs were found at CCMO, which was comparable to the amount found the previous year. At CCC, however, a total 1,077 billbugs were found in 2016, indicating a 22% popu - lation increase over 2015. It is worth noting that the areas installed with pitfall traps ac - counted for only 0.11% of the total area where insecticide applications were withdrawn. It is therefore reasonable to speculate that real bill - bug populations present at both fairways were much higher than indicated by the numbers trapped. The variation between the two sites is likely a reflection of multiple factors, includ - ing whether the roughs — 20 feet away from the monitored areas on both fairways — were regularly treated with insecticides. On the two fairways, hunting billbug ap - peared to be the dominant species (Figure 4). At CCC, bluegrass billbugs collected ac - counted for 13.7% and 9% of the population in 2015 and 2016, respectively. At CCMO, however, we found only six bluegrass billbugs in 2015 and none in 2016. Previous research demonstrated that both billbug species can survive on a wide range of turfgrass species, including tall fescue (Festuca arundinacea Schreb.) and Kentucky bluegrass, the pri - mary grass species for roughs, and zoysiagrass, the species for fairways at the two sites (3,6). However, why such a discrepancy in popula - tion composition was found at the two fair- ways, even though the turfgrass species at both sites were comparable, is unclear. Despite the difference in population size and composition, activity of billbug adults at Billbug count, April 2015 Figure 3. Pitfall traps installed on zoysiagrass fairways of Columbia Country Club (top) and Country Club of Missouri (bottom) in April 2015. Photos by Brett Loman

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