Colonization of N. densiflorus tissues by P. ramorum is not well understood. The pathogen is able to colonize nearly all tissues of this host but it is unclear how a tree is ultimately killed. Because this is such a destructive invasive pathogen, it is important to investigate its pathogenic strategy....
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Everett M. Hansen
Colonization of N. densiflorus tissues by P. ramorum is not well
Studies to identify the environmental factors that influence the rate of ectotrophic mycelial growth of Phellinus weirii (Murr.) Gilbertson along Douglas-fir roots were undertaken both in the laboratory and in the field. The effects of soil pH, nitrogen, moisture, temperature, microorganisms and bulk density were investigated. In the lab, the...
Phellinus weirii (Murr.) Gilbertson, cause of laminated
root and butt rot, is a heterothallic basidiomycete lacking
clamp connections. Two biological species groups of the fungus
have been hypothesized, the Douglas-fir and cedar-types, on the
basis of physiological, morphological and epidemiological
differences. Single-spore and vegetative isolates differ in
cultural morphology, nuclear...
A study was conducted of the influence of various climatic and
soil factors on the development of onion pink root disease and of the
influences of temperature, light, pH, carbon and nitrogen sources,
and vitamins on the growth in vitro of an Oregon isolate of the pink
root fungus, Pyrenochaeta...
Wetlands and wet prairies are economically and environmentally valuable ecosystems, but many have been degraded or converted to other uses. As human understanding of wetlands' value has increased, restoration efforts have grown correspondingly. Restoration attempts use a diversity of methods, which often include seeding with native plant species. This thesis...
Pelvetiopsis limitata (Setchell) Gardner (Phaeophyta,
Fucales), collected on the central Oregon coast, was
studied by electron microscopy, and by light microscopy
using methacrylate embedding and toluidine blue, acid fuchsin,
PAS and anilin blue staining. The sperm of both P.
limitata and Pelvetia fastigiata (J. Agardh) DeToni (from
northern California) are...
This study was directed to improve our understanding of the ecology of Swiss needle cast (SNC) of Douglas-fir, a disease that produces extensive damage to forests and plantation in the coastal region of Oregon and Washington. A disease prediction model for the coastal area of Oregon was built by establishing...
The phytopathogen Phytophthora ramorum (Werres, DeCock & Man in't Veld), causal agent of Sudden Oak Death (SOD) of oaks (Quercus spp.) and tanoaks (Notholithocarpus densiflorus syn. Lithocarpus densiflorus), is established in coastal forests of the western United States. Since the discovery of SOD in the Douglas-fir / tanoak forests of...
In early 2000, unusual mortality of a native North American tree, golden chinquapin, was reported by the USDA-Forest Service. Dying trees exhibited girdling cankers in the inner bark of the lower bole, branch flagging and defoliation. Isolations from necrotic tissues and soil associated with diseased or killed trees yielded Phytophthora...