Cultural Control, Risk Assessment, and Environmentally Responsible Management of Scarab Grubs and Cutworms in Turfgrass

Cultural tactics that may reduce reliance on insecticides were evaluated against scarab grubs and black cutworms attacking turfgrasses. Withholding irrigation or high mowing during beetle flight, or spring application of aluminum sulfate, reduced infestations of Japanese beetle and masked chafer grubs. Grub densities were not affected by applications of lime or urea, nor by use of a heavy roller. Although tolerance varies, all cool-season turfgrasses, including endophytic cultivars, are susceptible to grubs. Economic thresholds, however, are higher than generally is thought. Feasibility of identifying grub "hot-spots" by monitoring adults with pheromones was demonstrated. Field studies suggested that black cutworm infestations on golf putting greens can be suppressed by clipping management, topdressing, and use of resistant grasses in peripheral areas. Applications and limitations of cultural control for turfgrass insects are discussed.