Release rates into water of monolinuron, desmetryne, and carbofuran from three different types of formulations have been studied to control aquatic weeds in running waters. The migration of active ingredients (AI) from conventional wettable powder formulations was complete within 1 day, while the migration from ethylene-vinyl acetate copolymeric matrix (EVA) lasted significantly longer due to low diffusion coefficients of monomeric pesticides in polymeric matrices Do = 10(-8)-10(-12) (cm2 X sec-1). The herbicidal action could be extrapolated up to several years. Release duration of AI from calcium alginate beads lasted 2 weeks. Herbicidal effectiveness of terbutryne-EVA formulation has been investigated in a laboratory-scale simulated flow system device with duckweed plants (Lemna minor) as test organism. Growth inhibition of duckweed could be achieved at approx 20 ppb terbutryne in steady state.
