Disclosed novel substituted 3-isothiazolones, salts thereof, metal complexes thereof, their preparation, agricultural compositions containing them, and their utilization in the control of living organisms. In particular, novel 5-(substituted thiocarbamoyl)thio-2-substituted-4-isothiazolin-3-ones and related compounds including 5-piperidino and 5-cyano derivatives are disclosed.