Persistence of Dichlobenil in a Farm Pond

A farm pond in New York State was treated with dichlobenil (2,6-dichlorobenzonitrile) at the rate of 10 1b of active ingredient per surface acre and residues of the herbicide were determined in both the water and hydrosoil. Maximum concentrations of dichlobenil measured in the water and hydrosoil were 1.4 and 8 ppm, respectively. These concentrations were found in samples taken 7 days after treatment. After 7 weeks, 85 and 78% of the maximum detected levels of the herbicide in the water and hydrosoil, respectively, had disappeared. The concentration of dichlobenil had decreased to 0.002 ppm in the water and 0.13 ppm in the hydrosoil, 140 days after treatment.