Studies to identify the environmental factors that influence the rate of ectotrophic mycelial growth of Phellinus weirii (Murr.) Gilbertson along Douglas-fir roots were undertaken both in the laboratory and in the field. The effects of soil pH, nitrogen, moisture, temperature, microorganisms and bulk density were investigated. In the lab, the...
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...
Colonization of N. densiflorus tissues by P. ramorum is not well understood. The pathogen is able to colonize nearly all tissues of this host but it is unclear how a tree is ultimately killed. Because this is such a destructive invasive pathogen, it is important to investigate its pathogenic strategy....
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Everett M. Hansen
Colonization of N. densiflorus tissues by P. ramorum is not well
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...
Laminated root rot of Douglas-fir (Pseudotsuga menziesii (Mirb.)
Franco) caused by the fungus Phellinus weirii (Murr.)Gilbertson was
studied in two successive stands in the Oregon Coast Range. Damage
due to the disease in a 60-year-old second-growth stand was compared
with incidence in the preceding 300-year-old stand on the same site....
Groups of second-growth Douglas-fir (Mirb.) Franco were excavated
in plots of two to six trees on two sites in the vicinity of Cowichan
Lake, Vancouver Is., British Columbia. Eleven excavation plots provided
36 trees which could be studied in pairs (a total of 50 pairs) in order
to ascertain the...
Phellinus arctostaphyli (Long) Niemela, P. igniarius
(L. ex Fr.) Quel., and P. tremulae (Bond.) Bond. et Boriss.,
heartrotting hymenomycetes in the family Hymenochaetaceae
(Aphyllophorales), all conform to a multi-allelic heterothallic
mating system. Both compatible and incompatible
reactions result from pairings of homokaryons from the same
basidiocarp. Homokaryons isolated from different...
Described as one of the most destructive pathogens of agricultural crops and forest trees, Phytophthora is a genus of microorganisms containing over 100 known species. Phytophthora alni has caused collar and root disease in alders throughout Europe and a form of the species has recently been isolated in North America....
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...