Effect of turfgrass fungicides as secondary control agents for Japanese beetle, Popillia japonica Newman, larvae in turf

Japanese beetle, Popillia japonica Newman, larvae are common pests in turfgrass including home lawns, athletic fields, sod farms and golf courses. Consequently, annual insecticide applications are made each year to prevent or correct feeding damage. However, rarely are Japanese beetle larvae found on golf course putting greens. There are two existing theories to support this phenomenon: 1) the soil texture of golf course putting greens is not conducive to larval survival and 2) applications of fungicides to putting greens adversely affect larval survival. This study investigated the effect of several commonly used turfgrass fungicides on survival of Japanese beetle larvae in creeping bentgrass (Agrostis stolonifera L.), the predominant turfgrass species on golf course putting greens in the United States. The respective fungicide treatments included: 1) Heritage (azoxystrobin); 2) Chipco 26GT (iprodione); 3) Cleary’s 3336 (thiophanate-methyl); 4) Daconil (chlorathionil); and 5) Banner Max (propiconizol). The results of our study revealed that most of the fungicides tested exhibited good control of Japanese beetle larvae. Among the fungicides tested, Daconil had the highest level of efficacy of Japanese beetle larvae. The results of this study may reduce the amount of insecticides that are applied to turfgrass as fungicide treatments are more common and occur more frequently.