Pathogenicity of Blue-Stain Fungi Associated with Dendroctonus terebrans. Karen K. Rane, Department of Plant Pathology, University of Massachusetts, Amherst 01003. Terry A. Tattar, Department of Plant Pathology, University of Massachusetts, Amherst 01003. Plant Dis. 71:879-883. Accepted for publication 26 January 1987. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/PD-71-0879.

Three fungi (Leptographium terebrantis, L. procerum, and Ceratocystis ips) were consistently isolated from adult Dendroctonus terebrans and inner bark tissues around larval galleries in Pinus thunbergiana and P. sylvestris. Of the three fungi tested, only L. terebrantis was pathogenic to P. thunbergiana and P. sylvestris seedlings. The fungus caused inner bark necrosis and interruption of water conduction, as measured by xylem pressure potential and diffusive resistance, before foliar symptoms and blue stain developed in the xylem. Seedlings inoculated with C. ips and L. procerum developed necrosis of the inner bark tissues around the inoculation sites, but no effect on diffusive resistance or xylem pressure potential was detected.