A series of new quaternary ammonium salts (QASs) containing a terpenoid moiety derived from perillyl alcohol, citronellol, and geraniol was synthesized. Structures of all novel compounds were confirmed by spectral methods and elemental analyses. Fungicidal activity of the obtained compounds against six plant pathogens, against four fungi destroying wood and technical materials as well as herbicidal activity against ten species of temperate climate weeds has been examined. Several salts showed a higher antifungal and herbicidal activity than activity of the reference compounds.