Treesearch

A GIS-based method for locating potential tree-planting sites based on land cover data is introduced. Criteria were developed to identify locations that are spatially available for potential tree planting based on land cover, sufficient distance from impervious surfaces, a minimum amount of pervious surface, and no crown overlap with other trees. In an ArcGIS environment, a computer program was developed to iteratively search, test, and locate potential tree-planting sites by virtually planting large, medium and small trees on plantable areas, with large trees given priority as more...

One hundred-thirteen sites were established in perennial watercourses and sampled for 1 to 3 years between 2004 and 2006 to monitor for presence of Phytophthora ramorum throughout coastal central and northern California watersheds as well as portions of the Sierra Nevada mountain range (Murphy and others 2006). The majority of the monitored watersheds have limited or no P. ramorum at this time, but are near the epidemic range of P. ramorum and/or are considered high-risk for invasion by P. ramorum. Three currently infested watersheds in Sonoma and Mendocino counties were included as a...

Risk-based early detection surveys in U.S. forests were conducted between 2003 and 2006 using 100 m vegetation transects. Thirty-nine states surveyed 3,570 locations in states with endemic Phytophthora ramorum; states where the pathogen had been confirmed only in woody ornamental nurseries; and states that had received potentially infected stock but did not confirm the pathogen. A total of 12,699 samples from 44 host and associated host genera were collected and diagnosed for the pathogen using nested or real-time PCR. Phytophthora ramorum positive diagnoses were obtained for two samples...

Phytophthora ramorum was identified as the cause of a leaf blight on rhododendrons in an historic garden in Cornwall in 2003. A programme of measures was set in place to eradicate the disease from the garden and several sites were selected to monitor the effect of these measures on the recovery of P. ramorum from soil, leaf litter, rainwater and watercourses. The results from two monitoring sites are presented plus the results of leaf baiting of the watercourses. After the removal of the infected rhododendron at Site 1 and the application of a composted mulch over the soil surface, P....

The tree species that dominate the cloud-zone forests of Macaronesia, the coastal redwoods of California, the Valdivian forests of Chile, the Atlantic forests of Brazil and the podocarp forests of New Zealand are all examples of paleoendemic species that once had a much wider distribution. They appear to owe their survival to the particular environmental conditions provided by coastal sites or oceanic islands. Some of these coastal areas unfortunately have proved unique scenarios for the establishment and spread of exotic aerial Phytophthoras such as P. ramorum and P. kernoviae. The most...

Phytophthora ramorum was found for the first time in Scotland in April 2002 on some Viburnum tinus plants in a nursery. Seventeen more outbreaks were confirmed in the same year, all on plants moving in horticultural trade. Phytosanitary emergency measures to eradicate the disease were taken, such as destruction of infected plants followed by movement restrictions for potential hosts in the affected premises and increased monitoring. These measures proved to be successful. Already in the following year the number of outbreaks declined dramatically to six, followed by five in 2004,three in...

An unknown Phytophthora species was recovered from rhododendron and tanoak leaf baits used for monitoring streams and soils in Southwestern Oregon for the presence of Phytophthora ramorum. Isolates of this species yielded ITS-DNA sequences that differed substantially from other Phytophthora sequences in GenBank. Morphological features also differed from descriptions of known Phytophthora species. Based on the combination of unique morphology and unique ITS sequences, a new species is proposed. The new species, Phytophthora siskiyouensis, is homothallic, with globose to sub-globose oogonia,...

Two recently described pathogenic oomycetes, Phytophthora nemorosa and P. pseudosyringae, have overlapping host and geographic ranges in California and Oregon forests with P. ramorum, causal agent of ?sudden oak death? disease. Preliminary genetic evidence indicates P. nemorosa and P. pseudosyringae may be introduced in this region; their sympatric distribution with P. ramorum suggests they may be an interacting factor in P. ramorum disease.The ultimate goal of this project is to characterize the outcome of interaction during infection by P. ramorum, P. nemorosa and P. pseudosyringae in...

Phytophthora ramorum, cause of sudden oak death of trees or ramorum blight of other plant species, has many hosts. Some geographic regions, such as the Appalachian range of the eastern United States, are considered high risk of becoming infested with the pathogen because known susceptible plants occur there and climatic characteristics appear favorable for infections by this pathogen. We collected foliage of a range of plant species native to Appalachia in Kentucky during two summer seasons, and inoculated the foliage in Oregon with P. ramorum to determine relative susceptibility. Some...

Plant health regulations to prevent the introduction and spread of Phytophthora ramorum and P. kernoviae require rapid, cost effective diagnostic methods for screening large numbers of plant samples at the time of inspection. Current on-site techniques require expensive equipment, considerable expertise and are not suited for plant health inspectors. Therefore, an extensive evaluation of a commercially available lateral flow device (LFD) for Phytophthora species was performed involving four separate trials and 634 samples. The assay proved simple to use, provided results in a few minutes...