CERTAIN HERBICIDAL 1,2,4-TRIAZOLO(4,5-B)PYRIDINES

A compound of formula (I) : in which the dotted lines indicate the presence of two double bonds arranged so as to form a fused hetero-aromatic ring system; Ar is an optionally substituted aryl or heterocyclic ring; W is O or NR , where R is hydrogen or lower alkyl; X is (CH2)n, CH=CH, CH(OR )CH2, COCH2; where n is O, 1 or 2; R and R are independently selected from H, optionally substituted alkyl, alkenyl or alkynyl, halogen, NR R or R and R together with the carbon to which they are attached form an optionally substituted alkenyl or cycloalkyl group; R is CO2R , CN, COR , CH2OR , CH(OH)R , CH(OR )R , CSNH2, COSR , CSOR , CONHSO2R , CONR R , CONHNR R , CONHNR R R R , CO2R or COON=CR R ; R is an agriculturally acceptable cation; and R is an agriculturally acceptable anion; R , R and R are independently selected from H or an optionally substituted alkyl, aryl, alkenyl or alkynyl group; and R , R , R , R , and R are independently selected from H or an optionally substituted alkyl, alkenyl, aryl or alkynyl group or any two of R , R , R , R and R together with the atom to which they are attached form a cycloalkyl or heterocyclic ring. Compounds of formula (I) are herbicidal and composition containing them and methods of treatment using them are also described.