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...
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...
Root rot due to Armillariella mellea (Vahl. ex Fr.)
Karst. is unusually severe in ponderosa pine near Glenwood,
Washington. Isolate relations, clonal variability, vegetation
patterns, and climate were examined in relation to
severity of disease in this area.
Ninety-one isolates from 70 infection centers were
examined. Pairings of neighboring isolates...