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Poster: Diseases of Plants: Disease Detection & Diagnosis


Phytogenetic identification of pathogenic and endophytic fungal populations in west coast Douglas-fir foliage
D. DANIELS (1), J. Kiser (1) (1) Oregon State University, U.S.A.

Douglas-fir provides social, economic and ecological benefits in the Pacific Northwest (PNW). Minor defoliation has been linked to Swiss Needle Cast, associated with Phaeocryptopus gaeumannii. Unprecedented defoliation has increased since the 1990s, leading to decreased growth and yield. Affected areas exceed 500,000 acres in Oregon. Recent symptoms are inconsistent with predicted effects of P. gaeumannii. We hypothesize that the entire endophytic community is relevant to disease ecology, though this has not been investigated to date. Dynamics of needle cast are explored and baseline inventories of endophytes established by Sanger and Next-gen Sequencing (NGS). Endophytes were evaluated along environmental gradients at three sites in the PNW. Probability of occurrence (presence or absence of any endophyte in needle) was hypothesized to be higher in cooler, wetter climates. Preliminary results suggest that the probability of endophyte occurrence at the cool, wet site was 2.6 (p<0.0007) times higher than at the warm, dry site, and 3.7 (p<0.0001) times higher than at the warm, wet site. Despite advances in technology, few studies have identified endophytes in Douglas-fir by molecular means. Traditional culturing is hypothesized to be less effective than NGS. More inclusive identification could lead to greater efficiency in forest management. It is vital to understand the complete etiology of SNC and the ecological implications of disease in this important species.