Effect of irrigation on the efficacy of insecticides for controlling two species of mole crickets (Orthoptera:...

Effects of irrigation regimen, quantity, and timing on the efficacy of three insecticides for controlling nymphs of the southern mole cricket, Scapteriscus borellii Giglio-Tos, and the tawny mole cricket, Scapteriscus vicinus Scudder, were studied on golf courses in 1997, 1998, and 1999. Two irrigation regimen tests using two rates of bifenthrin and lambda-cyhalothrin produced inconclusive results. Mole cricket damage ratings after the applications of bifenthrin (60 g [AI]/ha) and lambda-cyhalothrin (76 g [AI]/ha) were not significantly different among the four irrigation regimens (non-irrigation, irrigation before treatment, irrigation after treatment, and irrigation before and after treatment). Mole cricket damage rating after the application of bifenthrin (120 g [AI]/ha) under irrigation before and after irrigation was significantly better than those under other irrigation regimens at 14 and 21 d after treatment (DAT). Different irrigation quantity and irrigation timing (after insecticide treatment) did not significantly affect the performance of imidacloprid (434 g [AI]/ha) in the 1998 tests. However, the results from the 1999 test indicated that mole cricket damage ratings from the imidacloprid-treated plots were significantly different between 2 and 0.5 cm irrigation water after treatment at 21 and 28 DAT. Application of bifenthrin at a rate of 120 g (AI)/ha with 0.5 cm of irrigation water after treatment resulted in significantly lower mole cricket damage ratings than those of 1.0 and 2.0 cm of irrigation water after treatment at 30 DAT only in the 1998 test. Bifenthrin with irrigation at 1 h after insecticide treatment provided better mole cricket control than that of irrigation at 5 min after treatment at 30 DAT only in the 1998 test. Mole cricket damage ratings after application of bifenthrin were not significantly different between either irrigation quantity treatment or irrigation timing treatment in the 1999 tests. Possible effects of application timing, environmental conditions, irrigation practice, and insecticide physical properties on the results are discussed.