Treesearch

The town of Oakville, Ontario, is located along the north shore of Lake Ontario between Toronto and Hamilton. In the fall of 2002, significant oak (Quercus spp.) mortality was observed at Oakville's Iroquois Shoreline Woods Park, an environmentally significant forest remnant noted for its oak-dominated forests. Investigations suggested that oak decline was responsible for the widespread mortality and that other nearby forest lands were also affected. Oak decline is a disease complex brought on by multiple stresses (e.g., drought, defoliation, high stocking, tree senescence) and secondary...

Ash (Fraxinus sp.) is an important component of upland sites and is dominant in lowland sites in Southwestern Ontario. While information on emerald ash borer (Agrilus planipennis) (EAB) and its signs and symptoms is readily available, there is little on management options that consider EAB affects. This paper was developed from a woodlot tour designed to transfer knowledge to farmers of good forestry and stewardship practices for managing ash. Three generic strategies for certain stand types and four site-specific prescriptions for woodlots in anticipation of EAB infestation are presented....

In situ baiting with whole, intact leaves of Rhododendron spp. has been employed since 2006 by the National Phytophthora ramorum Early Detection survey of forests (national survey). Using this method, P. ramorum was detected for the first time in national survey waterways draining 12 infested ornamental crop nurseries in Alabama, Florida, Georgia, Mississippi, North Carolina, and Washington as well as many forest areas in California and Oregon. In situ baiting periods lasting 1 to 3 weeks allow sampling large volumes of water over time, but also can result in loss of bait leaves from storm...

European phytosanitary measures as applied to nurseries require that potential host plants within a radius of 2 m of a Phytophthora ramorum-infected plant must be destroyed and that remaining host plants within a radius of 10 m cannot be traded until they are inspected and found to be pest free at further specific inspections. Despite the wide application and acceptance of these distances, they are not based on data regarding the in-field spread of this pathogen. Our previous study reported at the Fourth Sudden Oak Death Science Symposium demonstrated that direct aerial spread between...

In this study, viburnum (Viburnum) cuttings were treated with oomatistats (Subdue Maxx®, Banol®, and Aliette®) at standard rates for use as soil drenches or with biological control organisms (Streptomyces lydicus formulated as Actinovate SP® and used as a soil drench, and Trichoderma asperellum formulated in wheat bran and used as a top dressing) 4 days after roots were infected with Phytophthora ramorum. The amount of inoculum in runoff samples taken weekly for 5 weeks was studied using a quantitative assay analyzed as a mixed model regression and the percent colonization of roots at the...

Phytophthora ramorum, the fungus-like pathogen which causes sudden oak death, is a threat to the Pacific Northwest nursery industry. Because this is a quarantine organism, the destruction of plants and mitigation treatments resulting from a positive P. ramorum detection has caused millions of dollars in losses to the commercial nursery industry in California, Oregon, and Washington. There is concern about movement of the pathogen to nurseries and forests in the eastern United States. An increase has been seen in the NA2 and EU1 lineages from nursery samples in Washington in recent years,...

In most parts of Europe, rhododendron is the most important host for the spread of Phytophthora ramorum. To get a better knowledge of leaf infection and capacity for sporulation, infection studies were carried out. Detached leaves of the Rhododendron cultivar 'Catawbiense Grandiflorum' (CG) and the R. insigne hybrid `Brigitte´ (B) were inoculated with a zoospore suspension of a P. ramorum isolate of mating type A1 and A2, respectively. The CG developed much greater leaf necrosis than B (average after 55 days 106.5 mm2 versus 0.12 mm2). The trichomes on the B leaves seemed to prevent the...

Field observations and anecdotal evidence suggest that sudden oak death (SOD), a disease caused by the pathogen Phytophthora ramorum, may alter fuel loading in affected forests. Though it is reasonable to assume that a disease resulting in leaf blight, dead branches, and tree mortality would increase forest fuels, little work has been done to support or quantify this important issue. We compared fuel loading in P. ramorum-infested Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco)-tanoak (Notholithocarpus densiflorus (Hook. & Arn.) Manos, Cannon & S.H. Oh) forests of northwestern California...

in Scotland were genotyped using seven microsatellite markers as described by Vercauteren et al. (2010). Thirty multilocus genotypes were identified within the Scottish population, with 51 percent of the isolates belonging to the main European genotype EU1MG1 and 13 unique detected genotypes. Ten of those genotypes were site specific, often represented by single isolates. Three P. ramorum isolates, all from the same location, belonged to the new EU2 European lineage. The number of genotypes found in the managed environment was higher than the number found in the horticultural trade (25...

in Scotland were genotyped using seven microsatellite markers as described by Vercauteren et al. (2010). Thirty multilocus genotypes were identified within the Scottish population, with 51 percent of the isolates belonging to the main European genotype EU1MG1 and 13 unique detected genotypes. Ten of those genotypes were site specific, often represented by single isolates. Three P. ramorum isolates, all from the same location, belonged to the new EU2 European lineage. The number of genotypes found in the managed environment was higher than the number found in the horticultural trade (25...