Compositions comprising, as active ingredients, compounds of the formula I ##STR1## in which: X.sub.1, X.sub.2 and X.sub.3 independently of one another are hydrogen, methyl, methoxy, methylthio, halogen or nitro;A is C.sub.1 -C.sub.2 alkyl which is substituted by a maximum of 3 X--C.sub.1 -C.sub.4 alkyl groups, methyl which is substituted by 2 or 3 halogen atoms, ethyl which is substituted by hydroxyl and/or not more than 4 halogen atoms; vinyl which is unsubstituted or substituted by not more than 3 halogen atoms; furthermore ethynyl, propargyl, formyl, acetyl, acetyl which is substituted by not more than 3 halogen atoms, or one of the groups C(R).dbd.N--N(R.sub.2)R.sub.3, C(N.dbd.N--U.sub.1).dbd.N--NH--U.sub.1, CH(R)--[N(R.sub.1)].sub.n --N(R.sub.2)R.sub.3, C(R)(CN)OR.sub.4, C(R).dbd.N(O).sub.n R.sub.3, CH(R)--O--N.dbd.C(R.sub.1)R.sub.2, CH(R)--O--N.dbd.C(CN)--CONH--R.sub.5, C(R.sub.6).dbd.N--(O).sub.n R, CH(R)--Y--E--R.sub.3, CO--[C(OR).sub.2 ].sub.n Q, C(Q).dbd.CH--OR or T--Q; in which furthermore:n is zero or 1;X and Y independently of one another are oxygen or sulfur;R and R.sub.1 independently of one another are hydrogen or C.sub.1 -C.sub.2 alkyl;R.sub.2 is hydrogen, C.sub.1 -C.sub.8 alkyl, C.sub.3 -C.sub.6 alkenyl, C.sub.3 -C.sub.6 alkynyl, C.sub.3 -C.sub.7 cycloalkyl, benzyl or cyano;R.sub.3 is hydrogen, C.sub.1 -C.sub.6 alkyl, C.sub.3 -C.sub.6 alkenyl, C.sub.3 -C.sub.6 alkynyl, C.sub.3 -C.sub.7 cycloalkyl, benzyl or is an aryl radical U;R.sub.4 is hydrogen, C.sub.1 -C.sub.6 alkyl, Si(C.sub.1 -C.sub.6 alkyl).sub.3 or OCOC.sub.1 -C.sub.3 alkyl;R.sub.5 is hydrogen or CONHR.sub.1 ;R.sub.6 is N(R.sub.1)R.sub.2, hydrazino or Q;E is CO or SO.sub.2 ;U and U.sub.1 independently of one another are a phenyl radical which is unsubstituted or monosubstituted or polysubstituted by identical or different substituents from the series comprising methyl, methoxy, halogen, trifluoromethyl, nitro or cyano;T is C.sub.1 -C.sub.2 alkylene, methylene which is substituted by amino, hydroxyl or halogen, the substituents being independent of one another, or is ethenylene which is unsubstituted or substituted by halogen or cyano;Q is COXR or cyano.The novel compositions have crop-protecting properties and are particularly suitable for protecting plants against infestation by phytopathogenic microorganisms such as fungi, bacteria and viruses.