The root pathogen, Phytophthora lateralis Tucker and Milbrath,
continues its destructive spread among Port-Orford Cedars (Chamaecyparis
lawsoniana (Murr.) Parl.) of southwestern Oregon. This
thesis concerns spread of the fungus between root systems of
individual trees in a 49-year-old stand predominantly of Port-Orford-
Cedar. The contribution of root grafts to spread...
Phytophthora root rot decreases availability and quality of rhododendrons produced in the USA. Symptoms of Phytophthora root rot include root necrosis, leaf chlorosis, stunting, and permanent wilt. The purpose of this thesis was to better understand the impact of root damage, soil moisture, nitrogen fertilizer application, and pathogen species on...
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...
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...
Take-all root rot (Gaeumannomvces araminis var.tritici) is
a major disease of wheat (Triticum aestivum) in western Oregon.
Control of take-all is dependent on management practices such as crop
rotation and soil fertility-plant nutrition relationships. The
objective of this study was to develop a bioassay that could measure
the influences of...
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...