Wound Inoculations of Colorado Blue Spruce with Isolates of Leucostoma (Cytospora) Kunzei and other Cytospora Species

Thirty two isolates of Cytospora spp. recovered from various coniferous and deciduous hosts were used to wound inoculate intact and excised branch segments of mature Colorado blue spruce (Picea pungens) in two studies. All isolates of C. kunzei obtained from species of spruce consistently caused cankers on inoculated branches. Isolates of C. kunzei from other conifers varied in their ability to cause cankers. One of two isolates of C. /cunze/'from Douglas-fir and an isolate from eastern white pine were capable of inciting cankers while isolates from European larch and eastern hemlock failed to induce cankers. Isolates of other Cytospora species, collected from deciduous tree hosts, do not appear to play a significant role in the occurrence of Cytospora canker of Colorado blue spruce and should not be considered as a potential source of inoculum capable of infecting Colorado blue spruce.