Wood Ash Potential for Colorado Potato Beetle Control

Laboratory assays demonstrated that wood ash is toxic to adult and larval stages of the Colorado potato beetle. Insect mortality reached 100% among larvae and beetles continuously exposed to wood ash for periods of up to 10 days but remained below 22% after 4 repeated topical applications. The application of ash reduced feeding and activity level by adult stages, at least initially. The significant control observed in the laboratory did not extend to field application. Observations suggest that wood ash is inactivated by moisture and that hydrophobic formulations of wood ash would be required for outdoor application as an insecticide. Adult beetles did not avoid crossing thin strips of ash in the laboratory, but preliminary observations suggest that thick layers of ash could act as a physical barrier (fence) limiting colonization by beetles.