Compounds of formula ##STR1## wherein R.sup.1 represents a branched chain alkyl group of at least 4 carbon atoms or a cycloalkyl group of at least 4 carbon atoms; R.sup.2 and R.sup.3 are the same or different and each represents a hydrogen atom or an alkyl group of 1-6 carbon atoms; R.sup.4, r.sup.6 and R.sup.7 are the same or different and each represent a hydrogen or halogen atom or an alkyl or alkoxy group of 1-4 carbon atoms; and R.sup.5 represents an alkyl group, a substituted alkyl group, an aryl group or a substituted aryl group, Are outstanding herbicides and plant growth regulants.