BIOLOGICAL CONTROL APPROACH FOR MANAGEMENT OF DWARF MISTLETOES

Dwarf mistletoes (Arceuthobium spp.) are destructive forest pathogens that parasitise commercially important conifer species. Timber losses result from growth reduction, from wood degradation, from increased predisposition to attack by bark beetles, decay, and sapstain fungi, and ultimately from plantation failure. Research and experience in North America have demonstrated the potential use of hyperparasitic fungi as biological control agents for management of dwarf mistletoes. Although much information is available on the mycobiota associated with dwarf mistletoes, significant research and development are required for these to become operational tools. The most promising biological control agents are Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. in Penz. and Neonectria neomacrospora (C.Booth & Samuels) Mantiri & Samuels which attack shoots and berries, and the endophytic systems of dwarf mistletoe. The use of these two hyperparasitic fungi as potential biological control agents for management of dwarf mistletoes is under investigation. The development of an effective and efficient biological control strategy will reduce the impact of dwarf mistletoes on timber production in areas where traditional silvicultural control, such as retention silviculture or partial harvesting systems, is not practical.