Abstract Methods for controlling aquatic weeds that involve the use of 4-amino-3-chloro-6-(4 chloro-2-fluoro-3-methoxyphenyl)pyridine-2-carboxylic acids and agriculturally acceptable esters or salts thereof are described. Preferred herbicidal compositions allow for effective control and/or selectivity when treating a body of water to control target aquatic weed populations, such as a hydrilla, Eurasian watermilfoil and/or curlyleaf pondweed.