Plant growth-regulating and fungicidal compounds of the formula ##STR1## in which Ar represents optionally substituted aryl or optionally substituted heteroaryl,R.sup.1 represents hydrogen, alkyl, alkenyl, alkinyl, trialkylsilyl, optionally substituted phenylalkyl or an acyl radical,R.sup.2 represents halogen, cyano, thiocyano, alkylcarbonyloxy, alkylcarbonylthio or the groupings --X--R.sup.3 and --NR.sup.4 R.sup.5,R.sup.3 represents alkyl, cycloalkyl, alkenyl, alkinyl, hydroxyalkyl, alkylthioalkyl, carboxyalkyl, alkoxycarbonylalkyl, optionally substituted aryl, optionally substituted aralkyl or the radical of the formula ##STR2## R.sup.4 and R.sup.3 independently of one another represent hydrogen or alkyl, orR.sup.4 and R.sup.5, together with the nitrogen atom to which they are bonded, represent an optionally substituted cycloaliphatic ring which can contain further heteroatoms,X represents oxygen, sulphur, an SO group or an SO.sub.2 group, orR.sup.2 furthermore represents hydrogen when Ar represents optionally substituted heteroaryl, andY represents nitrogen or a CH group,or addition products thereof with acids or metal salts. Novel intermediates are also shown.