Agrobacterium tumefaciens and Agrobacteriwn rhizogenes, the causal agents of crown gall disease and hairy root disease, are known for their ability to transfer part of their
DNA (the T-DNA) from the bacterial tumor-inducing (Ti) plasmid to the genome of the
host plant. Interest has focused on these bacteria because they...
Armillaria (Fr. ex. Fr.) is a parasite whose pathogenicity
and role in forest ecosystems often depends upon the
physiological condition of the tree. Therefore, I tested the
frequency and severity of Armillaria ostoyae (Romagn.) Herink
infection among Abies grandis (Dougl.) Lindl., Larix
occidentalis Nutt., Pinus contorta var. latifolia (Engelm.),
Pinus...
The root disease fungus Inonotus tomentosus, common in the old
growth boreal forests of British Columbia, poses a threat to the
health of second growth forests established on sites with a previous
history of root disease. Colonized stumps occur in groups of 1 to 6;
the groups are clumped within...
An isolate of Coniothyrium obtained from a stem canker on
Nocturne rose from the Botany Department Farm, Corvallis, Oregon
was studied with respect to morphological and cultural characters,
pathogenicity and mineral nutrition. The hyphae of the isolate were
smooth, septate and branched. The hyphal cells averaged 16.37 X
3.52 microns....
The ecological interrelationships of mites occurring in
and near the Hood River Valley, Oregon, pome fruit orchards
were investigated to determine the possibility of an integrated
control program using the species already present.
Survey sampling methods were used to study mites on wild
hosts (Crataegus douglasii Lindl., Crataegus columbiana Howell,...
The genus Phytophthora contains some of the most destructive pathogens of forest trees, including the most destructive pathogen of alder in recent times, Phytophthora alni. Alder trees were reported to be suffering from canopy dieback in riparian ecosystems in western Oregon, which prompted a survey of alder health and monitoring...
This thesis addressed the potential of endemic predaceous and parasitic arthropods of
the Hood River Valley, Oregon to suppress the pear psylla, Cacopsylla pyricola F8rster.
Natural enemies adequately suppressed psylla in three of seven unsprayed orchards of
differing vegetational settings, orchard age, and size. Relatively few psylla natural enemies
dispersed...
