Previous studies have indicated that roots from five tree species (Picea sitchensis, Tsuga heterophylla, Pseudotsuga menziesii, Pinus ponderosa, and Pinus contorta) decompose at different rates across an environmental gradient in Oregon. Measurements of wood chemistry from each tree species as well as moisture and
temperature from each location do not...
White and grand fir are both valuable components of the mixed-conifer stand structure managed for late-successional reserves in central Oregon. However, they are often short-lived species because of high susceptibility to root diseases, defoliating insects, bark beetles, and wildfire. This study focuses on the effects of root diseases caused by...
The hundred-year history of the hazelnut industry in the Pacific Northwest is threatened by eastern filbert blight (EFB) caused by the fungus Anisogramma anomala (Peck) E. Müller. Marker-assisted selection (MAS) has been extensively used for ‘Gasaway’ resistance in the hazelnut breeding program at Oregon State University. Concern over breakdown of...
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...
The Willamette Valley, west of the Cascade mountain range in the state of Oregon, is home to a growing number of vineyards. This rather recent, booming industry of the region has become an important component of the economy of the state’s agriculture since the late 1960’s, contributing more than $1.56...
In early 2000, unusual mortality of a native North American tree, golden chinquapin, was reported by the USDA-Forest Service. Dying trees exhibited girdling cankers in the inner bark of the lower bole, branch flagging and defoliation. Isolations from necrotic tissues and soil associated with diseased or killed trees yielded Phytophthora...
The sudden oak death pathogen, Phytophthora ramorum, is present in southwestern Oregon, and while an eradication effort is underway, the potential impact of the polyphagous pathogen on surrounding vegetation is unknown. Plant communities in the area are substantially different from those affected in California, although tanoak (Lithocarpus densiflorus), evergreen huckleberry...
The primary objective of this research was to determine if native species within the genera Castilleja and Pedicularis are naturally infected by white pine blister rust (Cronartium ribicola) in whitebark pine ecosystems of the Oregon and Washington Cascade Range. Secondary objectives were to monitor the phenology of aecial and telial...
Since around 1923 Port-Orford-cedar (Chamaecyparis lawsoniana (A. Murray) Parl.) has been affected by Phytophthora root disease caused by the virulent introduced pathogen Phytophthora lateralis. A systematic resistance testing and breeding program located at the USDA Forest Service Dorena Genetic Resource Center in Cottage Grove, Oregon was initiated in 1997 with...
The Pacific Northwest has become one of the nation’s premier sweet cherry,
Prunus avium, production areas. As production of sweet cherries has flourished in
Oregon and Washington, so has powdery mildew, caused by the fungus
Podosphaera clandestina, which infects both foliage and fruit causing severe
economic damage to growers. Sweet...