The impact of various factors on seed production in a
Douglas-fir (Pseudotsuga menziesii) seed orchard in
western Oregon was examined by monitoring the fate of
seeds in thirty cones, stratified into three crown levels,
on each of ten trees during the 1984 growing season.
Cones were examined monthly between April...
A population of the Douglas-fir cone moth, Barbara colfaxiana
(Kft. ), was studied on the Buckhead Seed Production Area, Oakridge,
Oregon, during 1971 and 1972. A method of estimating cone and
insect populations is presented. Factors contributing to the mortality
of B. colfaxiana are discussed, with resinosis being the critical...
The root systems of Douglas-fir trees infected with
Verticicladiella wagenerii and assigned by crown color and terminal
growth characteristics to several stages of decline were excavated at
three widely separated sites in the Coast Range of Oregon. Data were
gathered on insect species present, extent of colonization of the root...
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...
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...
Verticicladiella wageneri Kendrick is a vascular wilt
pathogen of conifers, causing a black staining of
colonized sapwood of roots and lower stem. In Douglas-fir,
V. wageneri is intimately associated with insects.
Hylastes nigrinus, Pissodes fasciatus, and Steremnuis
carinatus are commonly associated with diseased hosts,
carry inoculum of V. wageneri in...
Phellinus weirii, the cause of laminated root rot, is considered the most destructive root rot of Douglas-fir, but little is known about the damage it causes, to a forest. The objective of this study was to determine silvicultural impacts of P. weirii on a managed forest. A survey located and...