Mobility and dissipation of ethofumesate and halofenozide in turfgrass andbare soil

The effect of turfgrass cover on the leaching and dissipation of ethofumesa te and halofenozide was studied. Sampling cylinders (20 cm diam. x 30 cm lo ng) were placed vertically in plots of creeping bentgrass (Agrostis palustr is Huds.), tall fescue (Festuca arundinaceae Schreb.), or bare soil. ethofu mesate [(+/-)-2-ethoxy-2,3-dihydro-3,3-dimethylbenzofuran-5-yl methansulfon ate] was applied at 840 g ai ha(-1) on September 21, 1997. Halofenozide (N- 4-chlorobenzoyl-N ' -benzoyl-N ' -tert-butylhydrazine) was applied at 1680 g ai ha(-1) on August 30, 1998. Replicate sampling cylinders were removed 2 h after treatment and 4, 8, 16, 32, and 64 days after treatment. Sampling cylinders were sectioned by depths and soil extracts were assayed by HPLC w ith a pesticide detection limit of P 01 mg kg(-1). Turfgrass was divided in to verdure and thatch and analyzed separately. ethofumesate leaching in tur fgrass was reduced by at least 95% compared to leaching in bare soil. The h alf-life of ethofumesate in bare soil was 51 days compared to 3 days in tur fgrass. Halofenozide showed similar leaching with or without turfgrass. Fif ty percent dissipation of halofenozide did not occur within 64 days, regard less of organic matter cover.