Phosphorylthio-acetyl derivatives of decahydroquinolines, octahydroindoles and octahydropyrindines are effective plant regulating agents (growth regulators and selective herbicides) and fungicides.The new phosphorylacylamines correspond to the formula I ##SPC1##wherein R.sub.1 and R.sub.2 each independently represents hydrogen or methyl, R.sub.3 represents alkyl or haloalkyl, R.sub.4 represents alkyl, alkoxy, haloalkoxy, alkylthio or an amino radical, X represents oxygen or sulphur, and one of the two indices m and n represents 1 and the other represents 0 or 1.