Phacelia capitata Rruckeberg is a member of the
Phacelia magellanica polyploid complex (species group
Magellanicae), a group of wide-ranging, polymorphic
perennials in western North America related to the South
American P. secunda (= P. magellanica). The purpose of
this project was to determine, to the extent possible, the
interrelationships of...
Isolates of Trichoderma spp. collected from snap bean foliage were tested for inhibition of grey mold of snap beans caused by Botrytis cinerea. In a detached blossom-pod assay an isolate of Trichoderma hamatum reduced pod rot by 94% compared to the nontreated check. Control was comparable to that obtained with...
Spore dispersal gradients and pod disease gradients from point
inoculum sources of Botrytis cinerea were measured over time in two
snap bean field experiments. Laboratory grown inoculum was placed
at ground level in a 30 x 30 cm square at bloom initiation and
removed at full bloom. Dispersal of inoculum,...
The role of unusual geologies in plant distribution and form is well-known. Serpentine (ultramafic) soils exert a particularly strong influence on plants, as evidenced by a high level of endemism and the morphological and physiological traits displayed in adaptation to the extraordinary chemistry of these substrates. Adaptation may lead to...
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Robert J. Meinke
The role of unusual geologies in plant distribution and form is
Plant pathogens in the genus Phytophthora are known to cause disease on field crops, nursery plants, and forest trees. The best known example probably is Phytophthora infestans, which triggered the infamous Irish potato famine. Other important Phytophthora species include: P. ramorum (sudden oak death pathogen), P. sojae (soybean root rot...
The study of the infra-specific ranks (i.e., subspecies and variety) can be considered
the study of the process of speciation. Astragalus lentiginosus Douglas ex Hooker
(Fabaceae) is the most taxon rich species in the U.S. flora currently including 40
taxonomic varieties. These varieties were described using traditional taxonomic
methods primarily...
Fungi play critical roles in ecosystem processes and interact with plant communities in mutualistic, pathogenic, and commensal ways. Fungal communities are thought to be influenced by both associated tree communities and soil properties. However, the relative importance of the biotic and abiotic drivers of soil fungal community structure and diversity...
Rhizopogon vesiculosus is a common ectomycorrhizal (EM) symbiont of Pseudotusga menziesii (Douglas-fir) in the coast range of the Pacific Northwest. The species has been studied for its systematics, genet size, population structure, and competitive ability in several field and experimental studies. This thesis seeks to provide a more thorough characterization...
Pyrenophora tritici-repentis (Ptr) is the necrotrophic fungus responsible for tan spot of wheat (Triticum aestivum). Ptr causes disease on susceptible wheat cultivars through the production and secretion of host-selective toxins (HSTs). HSTs are compounds that are only known to be produced by fungi and considered to be primary determinants of...