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...
To determine which isolates will most rapidly replace
Phellinus weirii in stumps and roots, Trichoderma spp. were
isolated from P. weirii-infested stumps and roots, identified, and
examined for growth rates and lethal effects on P. weirii in vitro.
Phellinus weirii-infested Douglas-fir stumps and stump roots
were sampled for microorganisms by...
Verticicladiella wageneri Kendr. is a vascular wilt pathogen of
Douglas-fir in the Pacific Northwest, The disease is characterized by
black staining of colonized sapwood; crown symptoms are those typical
of a wilting syndrome. Histopathological studies revealed that the
pathogen is limited to the xylem but causes vascular dysfunction in
both...
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...