WASHOFF OF DICAMBA AND 3,6-DICHLOROSALICYLIC ACID FROM TURFGRASS FOLIAGE

The functional relationships between rainfall intensities and amounts, and the washoff of dicamba and 3,6-DCSA from turfgrass foliage were d etermined. Dicamba was applied to Kentucky bluegrass field plots and t he turfgrass was subjected to 2 to 58 mm of simulated rainfall 18 to 4 8 h later. Rainfall was applied at an average intensity of 20.6 or 39. 9 mm h-1. The 39.9 mm h-1 intensity reduced dicamba washoff by 10% for a given amount of rainfall. Washoff of 3,6-DCSA was independent of ra infall intensity. When averaged over intensities, washoff of dicamba w as best described by the equation y = 1 - 0.341X0.187, and 3,6-DCSA wa shoff by the equation y = exp(-0.210x), where x represents millimeters of rainfall and y, the proportion of compound remaining on the foliag e after rainfall.