Efficacy and Longevity of Merit 75 WSP for Control of Black Turfgrass Ataenius Grubs
Summary: When applied at the recommended rate of 0.15 oz/1000 square feet, Merit 75 WP provided significantly better control of black turfgrass ataenius (BTA) grubs than no treatment for at least 35 days after treatment, and continued to show a non-significant trend towards improved grub control for four months. However, by six months after treatment, there were few differences between plots treated with Merit and those that were not treated. During periods of heavy grub pressure and high turf stress, control with Merit was insufficient to avoid some damage to greens. Merit treatments did not result in reduced damage from bird feeding.
Biological data on the BTA collected during this trial indicated that five or more generations occurred April and December, 1995. The highest density and most damaging grub generations occurred between July and September, 1995. Grub populations were found to be heavily aggregated, or clumped in their distribution. BTA grubs appeared to be more likely to occur on collars, or where soil was wet and water drainage was a problem. When BTA grub population data was compared with BTA adult population data obtained from a black light trap study also conducted at Los Coyotes Country Club, it was determined that grub infestations peaked 11 - 14 days after each adult peak.
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Principal Investigators: Wendy Gelernter and Larry Stowell
Cooperator: William Gallegos, Los Coyotes Country Club
