DOWNWARD MIGRATION OF METALAXYL FUNGICIDE IN CREEPING BENTGRASS SAND LYSIMETERS AS AFFECTED BY ORGANIC WASTE, PEAT AND ZEOLITE AMENDMENTS

Metalaxyl is a fungicide used for control of Pythium spp. diseases in turfgrass. The downward migration of metalaxyl was studied in irrigate d lysimeters containing a fine sandy loam soil; alone or sand amended with composted brewery waste, composted sewage sludge, peat or zeolite by analysis of the fungicide in leachates collected up to 65 days pos t application. The Arkport sandy loam soil and sand containing peat, b rewery waste or sewage sludge amendments showed somewhat similar patte rns of metalaxyl in collected leachates increasing from not detectable initially to peak concentrations between 14 and 21 days after first i rrigation and decreasing thereafter. The peak concentrations were in t he order: brewery waste > peat > sludge > Arkport sandy loam. In the l ysimeter treatments containing sand amended with zeolite, the downward migration of the fungicide with time after application generally incr eased with the highest attained concentration in the leachate inversel y proportional to the total amount of zeolite in the respective lysime ter sand profile. Only small percentages (ranging from 0.21 to 1.22) o f the total applied fungicide were accounted for in the leachates. The literature is reviewed and the possible mechanisms of fungicide losse s are discussed. (C) 1998 Elsevier Science Ltd. All rights reserved.