The invention relates to novel 4-(1H-azolylmethyl)-1,3-dioxolan-5-one derivatives of the formula I ##STR1## and to the production and use of these compounds. In formula I, R.sub.1 and R.sub.2 are unsubstituted or substituted alkyl or phenyl, or together form a 3- to 7-membered carbocyclic ring which is unsubstituted or substituted, A is an unsubstituted or substituted phenyl radical, and X is --CH.dbd. or --N.dbd.. The compounds of the formula I can be used in the form of appropriate compositions for regulating plant growth and/or for controlling and/or protecting plants from attack by phytopathogenic microorganisms.