Synergistic herbicidal composition containing certain pyridine or pyrimidine carboxylic acids and certain cereal and rice herbicides

A synergistic herbicidal mixture comprising an herbicidally effective amount of (a) a first herbicide selected from the group of a pyridine or a pyrimidine carboxylic acid of the formula (I)

• wherein X represents CH or N, hal represents F, Cl or Br, and R represents methyl or ethyl,
• and agriculturally acceptable salts, esters and amides of the carboxylic acid, and (b) a second herbicide selected from the group consisting of amidosulfuron, aminopyralid, beflubutamid, bensulfuron, bentazone, bispyribac, bromoxynil, carfentrazone, chlormequat, chlorotoluron, chlorsulfuron, clodinafop, clomazone, cyhalofop, dicamba, dichlorprop, diflufenican, diflufenzopyr, fenoxaprop, florasulam, flucarbazone, flufenacet, flupyrsulfuron, glyphosate, halosulfuron, imazamethabenz, imazamox, imazethapyr, indol-3-ylacetic acid, 4-indol-3-ylbutyric acid, iodosulfuron, isoproturon, isoxaben, MCPA, mesosulfuron, metribuzin, metsulfuron, norflurazon, penoxsulam, picolinafen, pinoxaden, propanil, propoxycarbazone, prosulfocarb, pyrasulfotole, pyrazosulfuron, pyriclor, pyroxsulam, quinclorac, sulcotrione, sulfosulfuron, thifensulfuron, tralkoxydim, tribenuron, triclopyr and mixtures thereof.