Using spatial autocorrelation analysis, we
examined the within-population genetic structure of
Rhizopogon vinicolor and R. vesiculosus, two hypogeous
ectomycorrhizal (EM) species that are sympatric
sister taxa known to differ in their clonal structure.
We collected 121 sporocarps and 482 tuberculate EM
of both species from a 20 ha forest stand...
Results from approximately 400 fungus-host pure culture
inoculations indicate that specificity of ectomycorrhizal associations
is a complex phenomenon and cannot be based solely on field observations
of sporocarp-host associations. Of the numerous sporocarp-host
specific fungi tested, most formed ectomycorrhizae with one or more
unexpected, non-associated hosts. These results conclusively demonstrate...
Before the arrival of Euro-Americans, the inland Pacific Northwest was settled by native
people whose frequent intentional burning of the landscape promoted open stands
dominated by large fire-resistant ponderosa pine. Fire suppression for nearly a century,
livestock grazing, and logging of the largest trees has resulted in forests characterized by...
Total length and biomass of fungal mycelium in the soil of a young Douglas-fir stand in the central Oregon Coast Range were estimated over 27 months with the agar-film technique. In a second study, phenology and taxonomy of hypogeous (belowground) sporocarps were studied over 32 months in a nearby, young...
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...
We investigated the root endophytic fungi of lupine using
four approaches: (1) occurrence of fungal colonization in field-collected
roots; (2) growth response of L. latifolius to inoculation
with two types of fungi; (3) structure of root colonizations of
Pinus and Lupinus by Phialocephala fortinii, a septate endophytic
fungus of lupine;...
The colonization of several species of plants by vesicularar-buscular
mycorrhizae (VAM) was studied to determine how host, soil,
or symbiont factors interacted to enhance growth of the host plant.
Seedlings of two species of the Cuppressaceae and two of the
Taxodiaceae formed VAM; colonization significantly improved growth.
This response to...
The ectomycorrhizal fungi Cenococcum geophilum, Hebeloma
crustuliniforme and Laccaria laccata produced ethylene in vitro in
modified Melin-Norkrans liquid medium only if amended with 2.5 to
10 mM methionine; Pisolithus tinctorius failed to produce ethylene
unless the cultures were renewed with fresh methionine-amended
medium prior to ethylene assay. An additional 19...
Fusarium spp. frequent conifer nursery soils yet are rarely recovered from coniferous forest soils. Experiments were performed to determine what influence humic-rich organic amendments and volatiles from soil, ectomycorrhizal fungi and ectomycorrhizae have on the populations of several physiologic and taxonomic microbial groups potentially related to this phenomenon. A comparative...
Wood is a major pool of organic carbon that is highly resistant to decay, owing largely to the presence of lignin. The only organisms capable of substantial lignin decay are white rot fungi in the Agaricomycetes, which also contains non–lignin-degrading brown rot and ectomycorrhizal species. Comparative analyses of 31 fungal...
Two objectives of this research were to identify fungi which are
mycorrhizal with western hemlock and to examine the ecology of hemlock
mycorrhizal fungi indigenous to outplanting sites. Another objective
was to evaluate the effectiveness of mycorrhizal inoculation in
improving the performance of outplanted hemlock seedlings.
A list of over...
Rhizopogon is a hypogeous fungal genus that forms ectomycorrhizae
with genera of the Pinaceae. The greatest number and species of
Rhizopogon are found in coniferous forests of the Pacific Northwestern
United States, where members of the Pinaceae are also concentrated.
Rhizopogon spp. are host-specific primarily with Pinus spp. and
Pseudotsuga...
In vitro growth of twelve isolates of Tither spp., the true truffles, was quantified by an agar-melt procedure. All isolates grew
poorly on media commonly used for the culture of mycorrhizal fungi, but responded markedly to the addition of nitrate, as well as other
inorganic ions, to malt and potato-dextrose...
Fusarium spp. are among the most important pathogens of Douglas-fir
(Pseudotsuga menziesii) seedlings in bareroot nurseries. Currently the most effective
disease control method is soil fumigation with methyl bromide. As methyl bromide is
phased out, however, other disease management strategies may become more important.
We explored two alternative approaches to...
Four isolates of Glomus mosseae, collected from diverse
geographic locations, were pot cultured on varied host plants or
stored in the same soil as collected. Spores of three isolates failed
to germinate on any of five agar media while the fourth germinated
well on all media. Lack of germination on...
The influence of vesicular-arbuscular mycorrhizae (VAM) on
populations of general taxonomic and functional groups of naturally-occurring
rhizosphere bacteria and actinomycetes associated with
roots of sweet corn (Zea mays var. rugosa) and subterranean clover
(Trifolium subterraneum L.) was assayed using selective media.
Sporangial production by Phytophthora cinnamomi was also used as...
Inoculations of white fir, Shasta red fir, Douglas fir and
ponderosa pine with Pisolithus tinctorius spores when outplanted
failed to produce P. tinctorius mycorrhizae at the end of the first
growing season. In the third year a few P. tinctorius mycorrhizae
were formed on white fir. Inoculations reduced seedling survival...
Alaska-cedar (Chamaecvparis nootkatensIs (D. Don) Spach) is a
valuable tree that is suffering from a serious decline and mortality of
unknown cause throughout southeast Alaska. Epidemiological and
pathological studies were initiated to determine if a pathogen is the
primary cause of this problem. By examining old aerial photographs and
by...
Mycorrhizal fungi in arid and semiarid rangelands have received little study in southwest Asia and north Africa, although they are important in food production and rangeland productivity. The desert truffles of the genera Terfezia and Tirmania form fruiting-bodies and mycorrhizae with rangeland plants. This thesis treats the taxonomy and the...
Three provisional species are described as new: Leucogaster
couchii, L. gelatinosus, and L. microsporus. Leucophlebs candida
is transferred to Leucogastef, completing the transfer of all
Leucophlebs species to Leucogaster. L. columellatus is transferred
to Sclerogaster. L. longisterigmatus is synonymized with
L. rubescens, L. foveolatus with L. odoratus, and L. fulvimaculatus...
Root rot of ponderosa pine caused by Armillaria mellea was
studied in a pine forest that had been under management for 30 years
in Klickitat County, Washington. Information sources included
disease survey, detailed observation and description of specific
disease situations, and examination of roots in situ and removed.
Roughly circular...
Hypogymnia imshaugii is one of the most common, conspicuous and morphologically variable epiphytic lichens of the Pacific coastal states and provinces. The species varies greatly in morphology and chemistry, suggesting multiple closely related species or one or more phenotypically plastic species. We sought to determine whether additional ecologically meaningful species...
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...
Phellinus weirii (Murr.) Gilbertson, cause of laminated
root and butt rot, is a heterothallic basidiomycete lacking
clamp connections. Two biological species groups of the fungus
have been hypothesized, the Douglas-fir and cedar-types, on the
basis of physiological, morphological and epidemiological
differences. Single-spore and vegetative isolates differ in
cultural morphology, nuclear...
Most plant toxicology tests developed in support of environmental laws use a single stress applied to an individual plant. While tests using individual species or stresses require fewer resources and are easier to interpret, they are under increasing criticism for being unrealistic and missing important ecological interactions. The objective of...
