Treesearch

Sudden oak death (SOD), caused by Phytophthora ramorum, was first diagnosed as the cause of a lethal canker disease of coast live oak (Quercus agrifolia), California black oak (Q. kelloggii), and tanoak (Notholithocarpus densiflorus) in 2000. Between 2005 and 2009, we initiated multiple field studies to test strategies for reducing SOD impacts in stands of tanoak and susceptible oaks. In oak forests, California bay laurel (Umbellularia californica) is the primary source of P. ramorum inoculum that infects oaks, and proximity to bay greatly increases disease risk (Swiecki and Bernhardt...

It has been long determined that Umbellularia californica (California bay laurel) is the key transmissive host for the sudden oak death pathogen (SOD, Phytophthora ramorum) in mixedoak woodlands, however the parameters of bay to oak disease transmission have not been fully clarified (Garbelotto and others 2003). Here, we concisely present results of three studies: one clarifying the parameters of bay to oak transmission, and two testing whether two cost-effective approaches involving selective removal of a limited number of California bay laurel trees may reduce disease incidence in...

The Marin Municipal Water District (MMWD) stewards 22,000 acres of watershed lands in Marin County. Recognized as a biodiversity hotspot, with over 1,000 plant taxa in more than 100 recognized communities, it is one of the first introduction sites of Phytophthora ramorum in California. In part to understand and monitor this new threat, MMWD completed its first Vegetation Classification and Map in 2005 with support from California Native Plant Society, California Department of Fish and Wildlife, and Aerial Information Systems (AIS). A 2010 remap of forested areas with support from the USDA...

The East Bay Regional Park District, the largest urban park network in the United States, includes extensive coast live oak (Quercus agrifolia)-dominated forests at the urban-wildland interface. Parks that encompass chaparral, grasslands, riparian habitats, and hardwood and conifer forests are adjacent to one of the most heavily-populated urban regions in the country. From 2008 to 2011, we placed 535 randomly assigned, 10 m radius fixed plots in coast live oakbay laurel (Umbellularia californica) stands in each of five parks to establish baseline disease conditions. The random design...

In this presentation I will illustrate the theoretical foundations for a proposed drastic change in how we respond to invasive alien forest pathogens, like Phytophthora ramorum. This new framework is the result of an in-depth analysis of the reasons why effective management of invasive alien phytophagous insects and phytopathogens (PIPs) in forest environments remains an elusive aspiration (Showalter and others 2018). A fundamental reason for why we continue failing is that such PIPs encounter evolutionarily naïve host trees in their new environments, which are incapable of mounting...

In coastal California, infection by the pathogen Phytophthora ramorum, causal agent of sudden oak death, results in extensive mortality of native oak species including Quercus agrifolia (coast live oak). However, apparently resistant Q. agrifolia have been observed within native populations. In this study (Conrad and others 2019), we monitored disease progression from 2010 to 2017 in Q. agrifolia artificially inoculated with P. ramorum and disease incidence in Q. agrifolia left to become naturally infected in the same stand. After seven years, 61% of artificially inoculated Q. agrifolia...

Sudden Oak Death (SOD), caused by Phytophthora ramorum, is lethal to tanoak (Notholithocarpus densiflorus) and threatens this species throughout its range in Oregon. In July 2001, the disease was first discovered in coastal southwest Oregon forests. Since 2001, an interagency team has been attempting to eradicate and slow the spread of disease through a program of early detection, survey and monitoring, and destruction of infected and nearby host plants. Eradication treatments, totaling approximately 2,550 ha (6,300 ac), eliminated disease from most infested sites, but the disease continued...

Phytophthora ramorum, cause of Sudden Oak Death (SOD), is an invasive pathogen that infects over 100 species of plants and has been introduced multiple times into the coastal forests of southern Oregon and northern California. In southwestern Oregon forests, tanoak (Notholithocarpus densiflorus) is the most susceptible species developing lethal stem cankers and sporulating from infected leaves and branches. The NA1 lineage was first reported in Oregon in the early 2000s and in 2015 the EU1 lineage was discovered infecting tanoak in the South Fork Pistol River drainage in Curry Co., Oregon....

Phytophthora ramorum garnered international attention upon its discovery in the summer of 2000 (Rizzo and others 2002), but thanks to genetic information collected from around the state, we know the pathogen has been in California since the 1980-1990s (Mascheretti and others 2008). As the decades pass and the possibility of large-scale eradication passes solidly out of reach, we continue to witness the transformation of our forests. New tree mortality ebbs and flows as pathogen populations contract and expand during years of severe drought followed by seasons with adequate rainfall....

The development of new C-320 electronic-nose (e-nose) methods for pre-symptomatic detection ofWhite-Nose Syndrome (WNS) in bats has required efficacy studies of instrument capabilities to discriminate between major sources of volatile organic compounds (VOCs) derived from clinical samples. In this phase-2 study, we further tested this e-nose for capabilities to distinguish between bat species based on differences in whole-body VOC emissions. Live healthy individuals of nine bat species were temporarily captured outside of caves in Arkansas and Louisiana. VOC emissions from bats were...