Infection of Arceuthobium americanum by Colletotrichum gloeosporioides and its potential for inundative biological control

Inundative biological control of Arceuthobium americanum occurring on Pinus contorta var. latifolia with the fungus Colletotrichum gloeosporioides was investigated. Isolates of C. gloeosporioides were collected throughout British Columbia, Canada, and one isolate was selected for assessment based on its growth and sporulation in culture. The fungus was formulated using the ‘Stabileze’ method and inoculated onto A. americanum under field conditions. It became established on some replicates and there was a higher incidence of C. gloeosporioides on treated replicates than controls. In some replicates, the treatment reduced fruit production, leading to a decrease in the reproductive capacity of the dwarf mistletoe plant; however, the efficacy was highly variable and not significant.