Treesearch

Phytophthora ramorum is well established over approximately 450 km of forests along the California coast. In the course of research on this emerging pathogen, two other aerial species of Phytophthora, P. nemorosa and P. pseudosyringae, were discovered. Little is known about the ecology and biology of these other species and how they interact with P. ramorum. Preliminary research has found that P. nemorosa and P. pseudosyringae have similar host and geographic ranges and cause similar disease symptoms as P. ramorum. However, P. nemorosa and P. pseudosyringae do not appear to cause landscape...

Recent research has shown that Phytophthora ramorum is a major threat to California’s coast live oak (Quercus agrifolia) dominated, mixed-evergreen forests (Rizzo and Garbelotto 2003). However, the role that diseases caused by other Phytophthora species play in the ecology of these forest communities is less evident. Surveys in mixed-evergreen forests have revealed two additional Phytophthora species, P. nemorosa and P. pseudosyringae. In these forests, P. nemorosa, P. pseudosyringae and P. ramorum are all aerial, canker-causing pathogens with overlapping host and geographic ranges....

The Pacific Southwest Research Station (PSW), U.S. Department of Agriculture (USDA) Forest Service initiated the Sudden Oak Death Research (SOD) Program in late 2000. The program was prompted by late fiscal year funding dedicated directly to begin research on this newly discovered disease. The history of discovery of Phytophthora ramorum, the causative agent of SOD, is now well known and will not be repeated here. During the initial start-up of the SOD Research Program, funding came from a variety of sources. Over the course of fiscal years (FY) 2001 and 2002, research funding was received...

This report quantifies benefits and costs for small, medium, and large broadleaf trees and one coniferous tree in the Piedmont region: the species chosen as representative are dogwood (Cornus florida), Southern magnolia (Magnolia grandiflora), red maple (Acer rubrum), and loblolly pine (Pinus taeda), respectively. The analysis describes "yard trees" (those planted in residential sites) and "public trees" (those planted on streets or in parks). We assume a 55% survival rate over a 40-year time frame. Tree care costs and mortality rates are based on results from a survey of municipal and...

California has more than twenty-five native species, natural hybrids, and varieties of oaks (Quercus species). The form of these oaks ranges from large trees, up to about 25 m tall, to shrubs no taller than about 1.5 m. California's native oaks include representatives of three oak subgroups or subgenera (Table 1). Hybridization only occurs between oaks in the same subgroup. In addition, some insects, pathogens, and other agents may selectively colonize or damage oaks in certain subgroups.

This report quantifies benefits and costs for typical small, medium, and large deciduous (losing their leaves every autumn) trees: crabapple, red oak, and hackberry (see "Common and Scientific Names" section). The analysis assumed that trees were planted in a residential yard or public site (streetside or park) with a 60 percent survival rate over a 40-year timeframe. Tree care costs were based on results from a survey of municipal and commercial arborists. Benefits were calculated by using tree growth curves and numerical models that consider regional climate, building characteristics,...

This report quantifies benefits and costs for representative large, medium, and small broadleaf trees and coniferous trees in the Coastal Plain region: the species chosen as representative are the Southern live oak (Quercus virginiana), Southern magnolia (Magnolia grandiflora), flowering dogwood (Cornus florida), and loblolly pine (Pinus taeda), respectively. The analysis describes "yard trees" (those planted in residential sites) and "public trees" (those planted on streets or in parks). Benefits are calculated using tree growth curves and numerical models that consider regional climate,...

Coast live oaks, Quercus agrifolia, infected with Phytophthora ramorum in California produce a characteristic sequence of symptoms and signs. Ambrosia beetles consistently tunnel into the bark of bleeding cankers in naturally infected trees. In field monitoring conducted since 2000, every bleeding coast live oak that subsequently died had been colonized by beetles while bleeding cankers were the only symptom of P. ramorum infection. Although the function of these beetles in decline and death of infected trees has not been confirmed, they likely disrupt nutrient and water conduction and...

The current understanding of diseases caused by Phytophthora ramorum and their dynamics in nursery crops is almost entirely derived from casual field observations. The objectives of the study are to help understand basic biological factors such as, inoculum viability, dispersal, and infectivity that influence disease occurrence and severity in a rhododendron nursery. The experiments were conducted under conditions that simulate a commercial containerized rhododendron nursery regime in the central coast of California. This extended abstract presents information on the findings of the first...

Recovery of Phytophthora ramorum from soils throughout Sudden Oak Death-affected regions of California illustrates that soil serves as an inoculum reservoir for the pathogen, but the potential for survival in soils throughout the summer is largely unknown. In this study we assess pathogen survival in infected leaf tissue in the upper soil profile in a redwood-tanoak forest ecosystem in Sonoma County, California.