PERSISTENCE OF BENSULFURON METHYL AND CONTROL OF HYDRILLA IN SHALLOW PONDS

Three shallow ponds near Welaka Florida were treated with 200 mug/l be nsulfuron methyl to determine its effectiveness for control of hydrill a (Hydrilla verticillata (L.f.) Royle) and to determine its persistenc e in the ponds. Biomass of mature hydrilla in the ponds decreased foll owing bensulfuron methyl application, but regrew within six months to pretreatment levels in two of the ponds. Newly sprouted hydrilla tuber s placed in soil in plastic pans, which were submerged in the ponds im mediately prior to treatment, were moribund one month following bensul furon methyl application. Initial concentrations of bensulfuron methyl in the ponds, predicted by regression analysis, were 233, 183, and 20 9 ppb. Half-lives of the compound in the ponds were 5.9, 8.1, and 9.1 days.