INFLUENCE OF SPRAY VOLUME, POST-APPLICATION IRRIGATION AND CANOPY HEIGHT ON THE PERSISTENCE AND DISTRIBUTION OF PRODIAMINE RESIDUES FOLLOWING APPLICATION TO A TALL FESCUE LAWN

摘要

The persistence of dislodgeable foliar residues (DFR) and soil residues following pesticide application is important because of implications regarding human exposure.This study investigated the effect of spray volume,post-application irrigation and canopy height on the persistence and distribution of foliar and soil residues following application of the pre-emergent herbicide prodiamine.Residue levels were determined over an 11-day period following 10 April 2006 application to a mature stand of ‘Confederate’ Tall Fescue (Festuca arundinacea Schreb).Increasing spray volume from 810 to 1,236 L ha-1 reduced DFR by an average of 3.8% over the entire study with significantly lower residue levels 3 hours after treatment (HAT),and 5,7,and 11 days after treatment (DAT).Increased spray volume resulted in an average of 46% less prodiamine soil residues with significantly lower residue levels 1,3,and 11 DAT.Clippings removed from plots 3 DAT which had received a spray volume of 810 or 1,236 L ha-1 contained DFR totaling approximately 13% of applied prodiamine.Post-application irrigation reduced DFR by an average of 10% over the entire study.Post-application irrigation increased soil residue levels measured 3,7,and 11 DAT by an average of 37% when compared to plots that did not receive post-application irrigation.Post-application irrigation reduced prodiamine loss on harvested clippings by 12% compared to turfgrass receiving no post-application irrigation.Increased canopy height did not significantly affect DFR retention during the study.