| Abstract: | A three-year field study was conducted using twelve 7.4×3.7 m plots and simulated rainfall to investigate pesticide run-off following application to a golf course fairway. The plots were sprigged with ‘Tifway 419’ bermudagrass (Cynodon dactylon×C transvaalensis). The dimethylamine salt of 2,4-D (2,4-dichlorophenoxy)acetic acid] was applied as foliar sprays at a rate of 2.24 kg AI ha−1. Simulated rainfall was applied at an intensity of 29 mm h−1 one day before and 1, 2, 4, and 8 days after the pesticide applications for 0.92, 1.75. 1.75, 0.92, and 0.92 h, respectively. Water run-off was measured using a tipping-bucket apparatus and sub-samples were analyzed for pesticide residues. Data collected from the study were also compared with the GLEAMS and PRZM-2 model simulations for surface water and 2,4-D run-off. Mass and concentration of 2,4-D in run-off decreased rapidly, with 74.5% of the total run-off of 2,4-D occurring in the first run-off event after treatment. When calibrated to the site-specific characteristics, the GLEAMS and the PRZM-2 models adequately simulated the average of surface water run-off over all plots, with normalized root mean square error (NRMSE) and coefficient of determination for linear regression (R2) being 22.8% and 0.917 for GLEAMS, and 23.7% and 0.879 for PRZM-2, respectively. However, both GLEAMS (NRMSE=82.1%, R2=0.776) and PRZM-2 (NRMSE=125.8%, R2=0.513) less accurately simulated 2,4-D concentrations in run-off. © 1999 Society of Chemical Industry |
