Winter squash (Cucurbita maxima) grown in Oregon’s Willamette Valley for edible seed, frozen foods, and fresh markets is susceptible to an undiagnosed soilborne disease. Diseased squash fields exhibit symptoms of stunting, root and crown rot, vascular discoloration, and late-season wilt, which in extreme cases can lead to total crop failure....
A potato plant growth and production model is developed with
the objectives of analyzing management alternatives and exploring
the nature of the early dying syndrome. The geographic area of
focus was the centerpivot irrigated circles of Oregon's Columbia
Basin. A problem analysis of the potato production system of this
area,...
The vegetation of the Oregon coast is characterized by a
variety of stages of plant succession which are repeated widely
throughout the sand dune area. During the years from 1960 to 1963
the gradation of upland sand dune succession was studied on 48 plots
within a 150 mile section of...
Modern plant pathology benefits from integrating methods and concepts from evolutionary biology. For example, evolutionary concepts are used to identify and examine species boundaries of plant pathogens, recognize processes underlying pathogen biogeography, identify traits that characterize emerging species, and discover new molecular interactions that originate under processes of selection. In...
The effects of ultraviolet (UV) irradiation on photosynthesis and
various partial reactions involving the individual photoreactions of
photosynthesis were examined. These reactions included photo-reduction in adapted green algae, Hill reaction, cyclic photophosphorylation,
the 520 nm absorbance change and variable-yield fluorescence.
The reactions were measured in spinach chloroplasts and
isolated chloroplasts...
Managers of forest and plantation ecosystems are encountering growing problems involving plant pathogens and the expanding geographic ranges of these pathogens. Historically unexposed stands are exceptionally vulnerable when a non-native pathogen is introduced because these pathogens can cause devastating disease in a host population that lacks co-evolved resistance mechanisms. One...
Plant-parasitic nematodes (PPN) pose a severe threat to crop production with the economic losses due to nematode parasitism in excessive of US$ 80 billion each year. Meloidogyne incognita, a globally distributed pest with a diverse host range, contributes significantly to this economic loss. The most reliable way to manage PPN...
Diseases can be a substantial threat to woody plant production, a major industry in Oregon. Boxwood (Buxus spp.) and rhododendron (Rhododendron subgenus Rhododendron and Hymenanthes) represent the top two broadleaf evergreen woody plants by farmgate value in Oregon. Historically, Phytophthora root rot has been considered the most destructive disease of...
Many mycorrhizosphere microorganisms can produce
plant growth regulating compounds in vitro. Plant growth
regulating compounds are known to mediate root growth and
development. In reforestation practices, conifer tree
seedling growth and survival are linked to rapid root
growth and development after outplanting. Multifactorial
experiments were conducted to document variations in...
The Mimulus washingtonensis complex is a group of morphologically similar
species centered in the Pacific Northwest. All are rare, and most are under
consideration for listing as endangered. Morphometric and pollination data were
used in developing a revised taxonomy for the group. Five species and two varieties
are recognized. Mimulus...