The control of phenoxyalkanoic acid herbicide resistant weeds has 4 amino -3- chloros -6-1999 (the fluoro- 3- anisyls of 4- chloros -2-) pyridine-2-carboxylic acids and its salt or ester
Pyridine -2- 4-chloro-2-fluoro-3-methoxyphenyl 4-Amino-3-chloro-6- () acid and its salt or ester have efficiently controlled phenoxyalkanoic acid herbicide-resistant weeds although the mode of action having the same and phenoxy alkane acid herbicide.