Pyridinyl derivatives of formula I ##STR1## wherein R.sub.1 to R.sub.5 are each independently hydrogen, halogen, C.sub.1 -C.sub.6 alkyl, C.sub.1 -C.sub.6 haloalkyl, C.sub.1 -C.sub.6 alkoxy, C.sub.1 -C.sub.6 haloalkoxy, cyano, C.sub.1 -C.sub.6 alkoxycarbonyl or phenyl,R.sub.6 and R.sub.7 are each independently of the other hydrogen, C.sub.1 -C.sub.6 alkyl, C.sub.3 -C.sub.6 alkenyl or C.sub.3 -C.sub.6 alkynyl, or phenyl or benzyl, each of which is unsubstituted or substituted by halogen, C.sub.1 -C.sub.6 alkyl, C.sub.1 -C.sub.6 haloalkyl, C.sub.1 -C.sub.6 alkoxy or C.sub.1 -C.sub.6 haloalkoxy,R.sub.8 is ##STR2## and R.sub.9 is hydrogen, C.sub.1 -C.sub.6 alkyl, C.sub.3 -C.sub.6 alkenyl, C.sub.3 -C.sub.6 alkynyl, or benzyl which is unsubstituted or substituted by halogen, C.sub.1 -C.sub.6 alkyl, C.sub.1 -C.sub.6 haloalkyl, C.sub.1 -C.sub.6 alkoxy or C.sub.1 -C.sub.6 haloalkoxy, or R.sub.9 is an acyl radical.The preparation of these compounds and the use thereof in pest control, in particular against bacteria and fungi, are described.