Herbizid

1,152,944. Herbicides containing pyridazone derivatives. BADISCHE ANELIN-& SODAFABRIK A.G. 8 Aug., 1966 [17 Aug., 1965; 25 Aug., 1965], No. 35330/66. Heading A5E. [Also in Division C2] Herbicidal compositions containing a compound of the formula:- wherein R1 is a phenyl radical (which may be substituted by halogen or lower alkyl), a cyclohexyl, cyclooctyl, or cyclohexenyl radical; R2 is a halogen atom; R3 and R4 together form the radical =C=O or =S=O, or R3 denotes hydrogen and R4 is the radical -COXR5 in which X denotes -O- or -S- and R5 is a C 1 to C 18 alkyl radical which may bear a hydroxyl, methoxyl, ethoxyl or carboxyl group, a chlorine or bromine atom, a thiocyano group or a dialkylamino group bearing C 1 to C 4 alkyl radicals; a C 3 or C 4 alkenyl radical which may bear chlorine substituents; a C 3 to C 6 alkynyl radical; a phenyl radical which may bear bromine, chlorine; hydroxyl or alkyl radicals as substituents; a cyclohexyl, cyclooctyl, benzyl, dimethylisocyano, dichlorocrotonolactone, tetrachlorotetrahydrofuryl, or bicycloheptenylmethylene radical or R5 denotes the radical: wherein R6 denotes an ethylene, propylene or butylene radical and R1, R2 and R3 have the above meaning and preparation of such compositions and a method of controlling unwanted plants wherein the plants or the soil in which the plants are to grow are treated with a phytotoxic quantity of a compound of the first general formula above. The compositions may be prepared in conventional manner by mixing the active ingredients with solid or liquid carriers, e.g. water, hydrocarbons, clay, fertilisers, borax or diatomaceous earth, and may optionally contain wetting agents, dispersing agents, adhesives or other biologically active ingredients. The activity of 1 -phenyl-4-sulphinylamino-5-chloropyridazone- 6, 1-phenyl-4-isocyanato-5-bromopyridazone-6 and N-(1-phenyl-5-chloropyridazon-6)-4-yl-carbamyl-#-hydroxyethyl ester when applied in aqueous suspension to the soil in which specified crop plants and unwanted plants are planted as seed's or have attained various stages of growth is described and compared with the activity of 1-phenyl-4-amino-5-chtoropyridazone-6 and 2-chloro-4, 6-bis (ethylamino)-s-triazine. Numerous other compounds of the first general formula above are also investigated.