Fusarium root infection of container-grown Douglas-fir: effect on survival and growth of outplanted seedlings and persistence of the pathogen

Greenhouse-grown Douglas-fir (Pseudotsuga menziesii var.glauca [Beissn.] Franco) seedlings with roots infected with eitherFusarium oxysporum Schlect. orFusarium proliferatum (Matsushima) Nirenberg were outplanted on a forest site in northern Idaho, U.S.A. No residentFusarium populations were detected in the forest soil.Fusarium persisted the first four years on roots initiated during the greenhouse phase, but occurred sparingly or was absent on roots that grew after outplanting. Height growth was unaffected, and mortality was not often associated withFusarium. A seasonal pattern ofFusarium activity was observed. Low levels (10–40%) of initial root infection apparently have little adverse effect on outplanting performance of Douglas-fir seedlings.University of Idaho, Idaho Forest, Wildlife and Range Experiment Station Contribution No. 640.