Residual control with insecticides of fall armyworm (Spodoptera frugiperda) on field treated Cynodon dactylon

摘要

The objective of the study was to evaluate the residual control for fall armyworm (Spodoptera frugiperda) (Lepidoptera: Noctuidae), provided by field applications of insecticides. Field plots of bermudagrass (Cynodon dactylon) cv. 'Common' were treated either in late July or early September 1996 with various insecticides. Residual control was bioassayed by feeding 4- or 5-d-old S. frugiperda larvae in the lab on grass samples that were harvested sequentially in time from the field plots. Treatmentswith one or more rates of acephate, bifenthrin, carbaryl, chlorpyrifos, deltamethrin, diazinon and lambda-cyhalothrin provided 100 percent control of larvae within 48 h after exposure on the grass that was harvested 1 DAT from field plots. Maximum residual corrected control >90 percent was provided as follows; lambda- cyhalothrin (13 DAT or longer), chlorpyrifos (9 DAT), acephate (4 DAT), diazinon (4 DAT), deltamethrin (4 DAT), carbaryl (3 DAT), and bifenthrin (1 DAT) after the grass was treated. The longer residual control (>90 percent for 9 vs. 5 DAT) provided by chlorpyrifos in September than in July may have been due to seasonal or environmental conditions. This method of treating field plots and exposing the treated grass sequentially in time tolarvae appears to provide an accurate estimate of the long term potential control for turf insecticides.