There is considerable variation among rose varieties in susceptibility
to mildew, and as a result of maturation, leaves of most
susceptible varieties become resistant to infection. The nature of
resistance has been sought in various studies involving environmental,
morphological, and physiological factors. An attempt was made in the
present investigation...
At the time of the eruptions of Lassen Peak in 1914-1915, an
area of vegetation along the east slope of the mountain approximately
1 1/4 miles wide and four miles long was destroyed. Except for a
few surviving trees, all vegetation was destroyed.
A study of the revegetation of this...
Three viruses were isolated from dahlias using a modification of
Yarwood's leaf-disc method of inoculation. Two of these isolates have
been reported previously in dahlias. In addition, a fourth virus was
isolated using a liquid-nitrogen transmission technique.
Dahlia virus isolate 1 possessed host range and thermal inactivation
properties similar to...
The demand for new fungicides to control plant diseases has
led to experimentation with both previously used and newly developed
fungicides. Silver, an older but little used fungicide, was selected for
evaluation because of its high toxicity to microorganisms. Silver
nitrate and a silver electrolytic cell were tested as potential...
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...
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...
Quercus garryana dominated plant communities are found in
the interior coastal valleys and on foothills from southeastern
Vancouver Island, British Columbia, south to San Francisco,
California. They occur as savannas, intermixed with a variety of
conifers, and in almost pure stands. The diversity of habitats
occupied by the species and...
A comparative study was made of Pinus ponderosa Laws, and
Arceuthobium campylopodum Engelm. f . campylopodum to determine
(1) whether or not the parasite or parasitized tissues accumulate
abnormal concentrations of minerals, (2) whether or not there
was evidence of a blockage of mineral translocation in the phloem
because of...
The main objectives of this study were to determine the
effect of certain environmental conditions on the quantity of poly-galacturonase (PG) produced by V. albo-atrum, and to partially
purify and characterize the PGs produced by this fungus in culture
and in infected tomato plants.
V. albo-atrum produced twenty times as...
Tissue differentiation of the primary root and its associated
laterals is reported. Secretory elements are the first of the primary
tissues to mature. They appear to be located between the precursory
phloem and pericycle in the primary root, but are more closely
associated with the pericycle in long lateral roots....
Contracting nucleolar vacuoles are a general and consistent
feature of somatic tobacco cells growing in microcultures. Nucleolar
vacuoles were studied in cells from callus tissues of two
single-cell clones, H-196 and H-239, of hybrid tobacco (Nicotiana
tabacum X N. glutinosa). Vacuoles periodically contracted either
completely or incompletely, apparently releasing a...
Many initially healthy Pelargonium seedlings developed symptoms
of Verticillium wilt in an Oregon State University greenhouse
when they attained blooming age. The symptoms first appeared in
May as "edge burning," yellowing, and wilting of leaves. In late
summer, these seedlings which were the offspring of Verticillium
infected plants, became severely...
Longevity and germination of seed of western dwarfmistletoe (Arceuthobium campylopodum Engelm. f. campylopodum) of ponderosa
pine (Pinus ponderosa Laws.) was investigated to determine:
1) the influence of humidity and temperature on seed viability and
deterioration during storage; 2) the physiology of seed dormancy;
3) the composition of seed reserve food...
More than 4,000 specimens of fruits and seeds were extracted
from the matrix removed from inside the skulls of sabre-tooth cats
excavated from various pits in the Rancho La Brea deposits. Of this
number, spproximately 1,445 specimens are involved in this study.
Many comparisons with modern fruits and seeds made...
Montane forest vegetation as it occurs on the east flank of the
central Oregon Cascades has provided excellent conditions for a
"natural experiment" in the use of various methodologies in studying
vegetational distribution. This "experiment" has reflected on some
theory and practice for the discipline of plant synecology. Detailed
descriptions,...
Three growth forms of the genus Microseris, of the tribe
Cichorieae, family Compositae, were compared with respect to their
anatomical structure. The purpose of this study was to clarify lines
of evolutionary specialization in the genus. Two of the three species
studied, M. laciniata and M. borealis, are perennials, while...
The infectivity of plant viruses was suppressed by
inhibitory substances (IS) in the sap of Chenopodium. Various
methods were attempted to find an efficient method which would allow direct transmission of viruses from Chenopodium to other plants. Viruses used in these experiments were alfalfa mosaic
virus (AMV), tobacco mosaic virus...
The Pacific Coast form of Douglas-fir in natural forest succession
is an intermediate species thriving in the Coast Range and
Cascade Mountains of the Pacific Northwest. This species constitutes
26 percent of the standing timber in the United States, and 24 percent
of the nation's annual timber harvest. Characteristics of...
A study was conducted to determine the influence of DMSO
(dimethyl sulfoxide) on suberization and wound periderm formation
in cut potato tuber tissue, and to determine the effectiveness of
DMSO as a potato seedpiece treatment for prevention of seedpiece
decay in the field. The influences of tuber storage conditions,
varieties,...
Crown gall infected and healthy Kalanchoe pinnata (Lam.)
Persoon plants were analyzed for soluble amino acids. Specifically
the amino acids in young leaf, mature leaf, stem, root, and gall
tissues were quantitatively measured. The plants were inoculated
with the bacterium, Agrobacterium tumefaciens (Smith and Townsend)
Conn., on one side of...
The Artemisia ludoviciana polyploid complex is a highly polymorphic
assembledge of eight taxa in the Pacific Northwest, with a
chromosome base number of x=9. A cytogenetic analysis of this
complex was carried out to determine the sources of its variation,
the types of polyploidy present, and the genetic processes active...
Pine needle blight of Pinus ponderosa Laws. caused by
Elytroderma deformans (Weir) Darker is recognized by changes in
the needles, in the bark and in the development of the branches.
Anatomical studies of the host-parasite relation have been made previously
on young pine tissue up to four years of age...
Partial reactions of photosynthesis were examined in the wild
type strain and six photosynthetic mutants (8, 11, 26, 40, 50, a') of
Scenedesmus obliquus, strain D₃. A reproducible procedure for the
isolation of active chloroplast fragments from Scenedesmus was
developed. Several chloroplast reactions were examined, as well
as two in...
A disease of sweet cherry (Prunus avium L.) known as "cherry
rosette" has threatened production of cherries in Oregon. In 1961
this disease was observed in widely separated orchards. Rosette
occurred in isolated trees or in spreading patterns, often from
identified single trees or from one section of an orchard....
Experiments were performed to determine whether a direct
correlation exists between the growth rates of tall and dwarf peas
grown either in the light or in the dark and endogenous gibberellin
(GA) content. Three separate but related experimental approaches
were utilized: (1) the determination of possible qualitative and /or
quantitative...
Verticillium dahliae Kleb. incites a vascular wilt disease of
mints. Susceptible Mentha piperita L. , resistant M. crispa L.,
and intermediate hybrid 148 were used to study 1) the site of differential
resistance and 2) the role of polygalacturonase (PG) in the
disease syndrome.
Many more V. dahliae propagules were...
Growth and replacement patterns of four successionally important
species occurring on Douglas fir clear-cuts were investigated
from September 1964 to June 1967. The study was carried out
on the Marys Peak watershed located near Corvallis, Oregon.
Species used in the study include Holcus lanatus, Senecio
jacobaea, Lotus crassifolius var. subglaber,...
The accumulation of dieldrin and its effects on species composition of benthic algal communities were studied in laboratory
streams. Effects of dieldrin on photosynthetic and respiratory
rates of the blue-green alga Phormidium retzii were determined using
a Gilson Differential Respirometer.
Dieldrin concentrations ranging from 0.05 to 7.0 ppb were
maintained...
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...
Abundant conidial production occurs from colonized straws and
plants infected with Cercosporella herpotrichoides Fron during the
cool moist months of the growing season. Experiments were
designed to study the survival, inoculum potential and competitive
saprophytic ability of conidia in soil.
Laboratory results indicated that cool moist soil favors the
saprophytic...
This study concerns factors affecting production and survival
of ascospores of Elytroderma deformans (Weir) Darker, a needle
cast of ponderosa pine (Pinus ponderosa Laws.).
The results show that summer cooling and a reduction in host
vigor delays and diminishes the number of fertile hysterothecia
produced. Evidence is offered for classification...
Soil moisture depletion trends under five plant species growing
on the clear-cuts of the Marys Peak Watershed near Corvallis,
Oregon, were followed during the summers of 1963 and 1964. The
species were Holcus lanatus, Lotus crassifolius var. subglaber,
Gaultheria shallon, Berberis nervosa, and Acer circinatum; and
were dominant plants of...
Abundant conidial and sclerotial production occurs on iris
plants infected with Botrytis convoluta Whetzel and Drayton during
the cool moist months of the year. Experiments were designed to
study the survival and inoculum potential of conidia and sclerotia.
Basic nutritional requirements of the fungus in culture were also
studied.
Results...
Many species of the Fagaceae have been variously interpreted
on the basis, primarily of external morphological characteristics.
The objectives of this study are to elucidate generic and specific
characteristics of the wood of Fagaceae and to attempt to obtain evidence
regarding taxonomic relationships among some of the species
occurring 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...
The hop cyst nematode, Heterodera humuli Filipjev, 1934 was
first reported from Europe in 1894, however, very little is known
with respect to the biology and economic importance of this pest.
Abundant material from Oregon hop yards provided an excellent
opportunity to add additional details concerning the bionomics of this...
Cultivated lilies include many garden varieties in addition to
the Easter lily, Lilium longiflorum Thunb. A popular member of
the garden group is Lilium speciosum Thunb., whose leaves can be
discolored by a virus symptom described as streak mottle. This
disorder is characterized by dashes of chlorotic tissue interspersed
with...
Ribonucleotide reductase from Rhizobium meliloti has been
partially purified and characterized. The enzymatic reduction of
ribonucleotides to deoxyribonucleotides is dependent upon B₁₂ coenzyme
and dihydrolipoate.
B₁₂ coenzyme was more effective than B₁₂ coenzyme analogues
in the reductase reaction. The affinity of the R. meliloti
reductase system for B₁₂ coenzyme was...
Samples of benthic algae were collected from the Metolius River
of central Oregon at two-week intervals between April 15, 1967 and
March 9, 1968. Species of filamentous algae and diatoms present
were recorded for every sampling station on each sampling date.
Permanent mounts of diatom frustules were prepared.
This sampling...