Studies on the incidence of coniferous needle endophytes in the Pacific Northwest

The incidence of internal fungal infections has been scored in coniferous needles from 19 hostssampled in over 200 sites dispersed throughout western Oregon and southern Washington. Abiesgrandis.A. nzagnifica , Picea sitchensis ,Pseudotsuga menziesii. and Sequoia sempervirens haveproved congenial hosts for needle blade endophytes; petiole fungi are common in all species ofPicea and Tsuga sampled. An undescribed taxon in the Hemiphacidiaceae, Chloroscvpha spp.,Cryptocline spp., Leptostroma spp., Naemacychts spp.. Phomopsis spp., Phyllosticia sp., andseveral unidentified Coelomycetes with Phoma-like spores were the dominant fungal taxa in theconiferous hosts sampled. The observed patterns of species dominance and diversity suggest thatthe true population of endophytes has been inadequately sampled in the present study and that anorder of magnitude more intensive sampling might be required for real patterns of dominance anddiversity to emerge. Many endophytes are restricted to a single coniferous host or to a restrictedgroup of hosts. When similarity coefficients between coniferous species are computed on thebasis of their internal needle microfloras, the resultant taxonomic groupings appear similar tothose derived from consideration of conventional morphological criteria. Comparison of en-dophyte incidence with host distribution patterns for Pseudotsuga menziesii reveals that infec-tion rates decrease at high elevations and dry sites.