Treesearch

Profiles are provided for 5 forest Phytopthora species: P. kernoviae, P. pinifolia, P.alni, P. cinnamomi, P.katsurae. Also presented are a "Host and Habitat Index for Phytophthora Species in Oregon" and "Histopathological Investigations of the Infection Process and Propagule Development of Phytophthora ramorum on Rhododendron Leaves".

This study assesses the survival of Phytophthora ramorum in the root ball of Rhododendron container plants as well as in different rootless forest substrates and a horticultural potting medium. Following inoculation of the root balls, the aboveground plant parts stayed symptomless, whilst the pathogen could be recovered with a novel non-destructive baiting assay from the root balls until at least 8 months post-inoculation. Plating of surface-sterilized roots and direct microscopic analysis confirmed the presence of P. ramorum in the roots. Phytophthora ramorum could also be baited from the...

Our objectives were to establish inoculum density relationships between P. ramorum and selected hosts using detached leaf and whole-plant inoculations. Young plants and detached leaves of Quercus prinus (Chestnut oak), Q. rubra (Northern red oak), Acer rubrum (red maple), Kalmia latifolia (mountain laurel) and Rhododendron ‘Cunningham’s White’ were dipinoculated with varying numbers of P. ramorum sporangia, and the total number of diseased and healthy leaves recorded following incubation at 20ºC and 100% relative humidity. Calibration threshold estimates for obtaining 50%...

N2-fixing trees can affect stream water quality. This has been documented in temperate streams, but not in tropical ones, even though N2-fixing trees are prevalent in the tropics. We investigated the effects of the introduced, invasive tree, Falcataria moluccana albiziaon water quality of Hawaiian streams. Nutrient concentrations were measured in reaches above and below F. moluccana-dominated riparian zones of four streams over 14 mo, and benthic algal nutrient limitation was examined in one stream. NO3-+NO2- concentrations were up to 600 percent higher in reaches below F. moluccana stands...

A new species, Phytophthora pluvialis is described. P. pluvialis has been recovered from streams, soil and canopy drip in the mixed tanoak-Douglas-fir forest in Curry County, Oregon, and in two additional streams in other areas of western Oregon. It has been found only rarely in association with twig and stem cankers on tanoak but not with any other plant host. The earliest isolate of P. pluvialis was from soil in 2002. P. pluvialis is classified in ITS Clade 3.

Tanoaks, Notholithocarpus densiflorus (Hook. & Arn.) Manos, Cannon & S. H. Oh, are being killed by sudden oak death, caused by the pathogen Phytophthora ramorum Werres, de Cock & Man in't Veld. However, very little is known about the basic ecology of the species. Here we investigate the pollination ecology of tanoaks using insect-visitor observations along with a pollinator-exclusion study. Insect-visitor observations were conducted by citizen-scientist volunteers at three different sites in the Midpeninsula Regional Open Space District lands in the Coast Range of California in 2009....

To combat sudden oak death (SOD), scientists needed to understand its primary host – tanoak, Notholithocarpus densiflorus (Hook. & Arn.) Manos, Cannon & S. H. Oh (Fagaceae), so research was initiated on its distribution, utilization and natural history. This Madrono Special Issue presents much of what we have learned, over the past 10 years, about this endemic, broadleaf tree, common throughout coastal California and southwest Oregon. By assembling this work, we aim to synthesize new information about this important SOD host; apply the concepts and findings to conservation and management;...

Tanoak, Notholithocarpus densiflorus (Hook. & Arn.) Manos, Cannon & S. H. Oh (Fagaceae), is an important component of mixed-evergreen forests and woodlands in coastal California and Oregon, with incursions into the Sierra Nevada and the Klamath Ranges. Sudden Oak Death (SOD) is causing severe dieback and mortality in tanoak and could transform these ecosystems in areas where the pathogen Phytophthora ramorum S. Werres, A.W.A.M. de Cock can become established. Knowledge of genetic diversity within the species is important for both disease resistance screening, conservation and replanting in...

The geographic range of tanoak, Notholithocarpus densiflorus (Hook. & Arn.) Manos, Cannon & S. H. Oh (Fagaceae), encompasses tremendous physiographic variability, diverse plant communities, and complex disturbance regimes (e.g., development, timber harvest, and wildfire) that now also include serious threats posed by the invasive forest pathogen Phytophthora ramorum S. Werres, A.W.A.M. de Cock. Knowing where these disturbance factors interact is critical for developing comprehensive strategies for conserving the abundance, structure, and function of at-risk tanoak communities. In this...

To combat sudden oak death (SOD), scientists needed to understand its primary host – tanoak, Notholithocarpus densiflorus (Hook. & Arn.) Manos, Cannon & S. H. Oh (Fagaceae), so research was initiated on its distribution, utilization and natural history. This Madrono Special Issue presents much of what we have learned, over the past 10 years, about this endemic, broadleaf tree, common throughout coastal California and southwest Oregon. By assembling this work, we aim to synthesize new information about this important SOD host; apply the concepts and findings to conservation and management;...