LEACHING OF MECOPROP HERBICIDE THROUGH TURFGRASS SOILS

The downward movement of the herbicide, mecoprop [2-(4-chloro-2-methyl -phenoxy)propanoic acid], was studied in a silt loam and a fine sandy loam soil and an acid sand, each prepared in plots as lysimeters and s eeded with Penncross creeping bentgrass. The extent of pesticide leach ing was determined as a function of interval after last herbicide appl ication and volume of irrigation water. Mecoprop moved downward in sma ll but detectable concentrations in both soils but its rate of leachin g was high in the sand. The concentration of mecoprop in the leachates decreased progressively with increasing time after herbicide applicat ion in both soils and the sand. A method of analysis was developed bas ed on electron capture gas chromatographic determination of a ring nit rated and methylated mecoprop derivative. Factors affecting the downwa rd movement of herbicides of similar structure are discussed.