Larvae of Prionus californicus Motschulsky feed on the roots of many woody perennial plants and are economically important pests of hop Humulus lupulus L. (Urticales: Cannabaceae) and sweet cherry Prunus avium (L.) (Magnoliopsida: Rosaceae) in the United States Pacific Northwest and Intermountain West. Adult males are strongly attracted to a volatile sex pheromone, (3R,5S)-3,5-dimethyldodecanoic acid, produced by females. Here, we summarize the results of field experiments evaluating the synthetic pheromone in a blend of all four possible stereoisomers as a means for managing P. californicus in hop yards and sweet cherry orchards by mating disruption (MD). Mean capture of male beetles was lower, in all 3 yr of the study, from plots in commercial hop yards and sweet cherry orchards treated with synthetic P. californicus pheromone than from similar, untreated plots. Although trap catch was lower in sweet cherry, relative differences between trap catches from MD and nonmating disruption plots were similar to that seen in hop yards. The number of P. californicus larvae recovered from plots in hop yards treated for three consecutive growing seasons with synthetic pheromone was lower than in similar plots that were not treated with the pheromone or treated with the soil fumigant ethoprop. Our research demonstrates that deployment of synthetic P. californicus pheromone effectively reduces mate-finding by males, can effectively reduce larvae populations in pheromone-treated hop yards, and thus, has excellent potential for managing P. californicus in hop, sweet cherry, and perhaps in other crops where it or Prionus species are pests.