COMPOSITION FOR PROTECTING PLANT FROM DISEASE

Novel benzo-1,2,3-thiadiazole derivatives of the formula in which: R1, R2 and R3 independently of one another are hydrogen, halogen, methyl, methoxy or methylthio; A is -OR4, -SR4, -N(R5)R6, -N(R7)-N(R5)R6, -O-N=C(R8)R9, -N(R7)-OR10 or R4 is hydrogen or a mole equivalent of a metal ion or a protonated organic base, C1-C18-alkyl, C3-C35-alkyl which is interrupted by an oxygen or sulphur atom, C1-C8-alkyl which is substituted by halogen or -COOR7, C3-C6-alkenyl which is unsubstituted or substituted by halogen, C3-C6-alkynyl which is unsubstituted or substituted by halogen, or C4-C7-cycloalkyl which is substituted by halogen or methyl, an aryl radical or heterocyclic radical U having not more than 3 hetero atoms O, N and/or S, a radical U which is linked via an alkylene bridge which has not more than 6 carbon atoms and up to 2 oxygen atoms; U is unsubstituted or halogen-, C1-C3-alkyl- or C1-C4-alkoxy- substituted phenyl, phenoxyphenyl, biphenyl, 1- or 2-naphthyl, or a saturated or unsaturated 5- to 7-membered heterocycle V which is unsubstituted or monosubstituted or polysubstituted by halogen, C1-C3-alkyl and/or C1-C3-alkoxy; R and R independently of one another are hydrogen, C1-C8-alkyl, C1-C6-alkyl which is substituted by C1-C3-alkoxy and/or cyano, or C3-C6-alkenyl, C3-C6-alkynyl, C3-C7-cycloalkyl, a radical U, a radical U which is linked via an alkylene bridge having not more than 2 carbon atoms; or R5 and R6 together with the nitrogen atom form a 5- to 7-membered unsubstituted or methyl-substituted heterocycle W which has not more than 2 further hetero atoms O, N and/or S; R7 is hydrogen or C1-C4-alkyl; R8 and R9 independently of one another are hydrogen, C1-C6-alkyl, cyano, CONH2, CONHCONHR7, phenyl which is unsubstituted or substituted by halogen, C1-C3-alkyl or C1-C3-alkoxy; or, together with the carbon atom linking them, also a 5-7-membered carbocycle; and R10 is hydrogen, C1-C6-alkyl, C3-C6-alkenyl, C5-C1-cycloalkyl, phenyl or benzyl. The novel active substances have crop-protecting properties and are particularly suitable for the preventive protection of plants against attack by phytopathogenic microorganisms such as fungi, bacteria and viruses.