This dissertation describes patterns in epiphytic macrolichen community composition along a nitrogen deposition gradient in the Yosemite region of the Sierra Nevada in California. This region is part of the largest federal air quality Class 1 designated air-shed in the western United States, covering the entire crest of the Sierra...
Verticillium wilt of hops in Oregon, caused by Verticillium
dahliae Kleb., was first reported in 1956. Later, V. albo-atrum
Reinke & Berth. was also isolated from infected hop plants, and thus
both species of the fungus were shown to be the causal agents of the
disease in Oregon.
The purpose...
The order Cornales (dogwoods) is the earliest diverging lineage within the most diverse group of flowering plants, the asterids (>80,000 species). Although molecular phylogenetics have significantly improved our understanding of cornalean systematics, early phylogenetic relationships remain uncertain due to an initial rapid radiation. The fossil record of Cornales is extensive...
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Dean of the Graduate School
I understand that my dissertation will become part of the
Host-parasite interactions between the pathogen, Sphaerulina musiva, and its host, Populus spp., were examined in a series of studies. In the first study, variation in resistance of Populus nigra from 7 locations in Europe was differentiated based on the parameters cankers per cm and disease severity score. The analysis evaluated...
A saprozoic nematode, Diplogaster lheriteiri Maupas 1919,
was studied to determine its relationship to the plant pathogenic bacteria,
Agrobacterium tumefaciens (Smith and Townsend) Conn.,
Erwinia amylovora (Burrill) Winslow et al., Erwinia carotovora
(Jones) Holland, Pseudomonas phaseolicola (Burk. ) Dows.,
Xanthomonas campestris (Pam. ) Dows. and to a phage of A....
Pseudomonas is a diverse genus of Gram-negative bacteria that includes pathogens of plants, insects, and humans as well as environmental strains with no known pathogenicity. Pseudomonas fluorescens itself encompasses a heterologous group of bacteria that are prevalent in soil and on foliar and root surfaces of plants. Some strains of...
Recent investigations indicate that several latent viruses of
apples exist in common commercial apple stocks, but these viruses
and their relationships are incompletely understood. This thesis
describes investigations of crab apples as indicators of latent viruses
of apples.
Eighty-eight varieties and species of crab apples were tested
as indicators of...
The objectives of this study are to: 1) study the variations
among stands of old-growth Sitka spruce forest located within a relatively
restricted geographical area, 2) determine the relationship between
species distribution, vegetational pattern, and such site factors
as slope and aspect, and 3) ascertain the abruptness of phytosociological
change...