A fungicidal agent contains a phenylpropylammonium salt of the formula ##STR1## where R.sup.1, R.sup.2 and R.sup.3 are each hydrogen, unsubstituted or substituted alkyl, unsubstituted or substituted aryl or aralkyl, cycloalkyl, alkoxy, acyl or halogen, R.sup.4 is alkyl, alkenyl or alkoxy, R.sup.5 is alkyl, alkenyl, alkynyl or unsubstituted or substituted aralkyl, R.sup.6 and R.sup.7 are each hydrogen, alkyl, CH.sub.2 OH or OH, X is CH.sub.2, O, S, C.dbd.O, (CH.sub.2).sub.2 or CH.sub.2 CH--R.sup.8 where R.sup.8 is alkyl, m is 0, 1 or 2, n is 0 or 1 and Y.crclbar. is the anion of a non-phytotoxic acid, with the proviso that the bond represented by the broken line may be hydrogenated if m is 0 or 1, and is always hydrogenated if m is 2.