Treesearch

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....

1. Significant research has been devoted to the development of semiochemical repellents for mountain pine beetle Dendroctonus ponderosaeHopkins. Several formulations of the beetle's antiaggregation pheromone verbenone (4,6,6‐trimethylbicyclo[3.1.1]hept‐3‐en‐2‐one) are registered to protect pine trees and stands. 2. We compared the efficacy of verbenone and Verbenone Plus for protecting individual lodgepole pine Pinus contortaDougl. ex Loud. and small stands of P. contortafrom mortality attributed to D. ponderosae. Verbenone Plus is a blend of semiochemicals [(−)‐verbenone, acetophenone,...

The seventh sudden oak death science and management symposium provided a forum for current research concerning sudden oak death caused by the exotic, quarantine pathogen, Phytophthora ramorum. Nearly 50 submissions describing papers or posters on the following sudden oak death/P. ramorum topics are included: ecology, monitoring, and nursery and wildland management. Abstracts are also provided from sessions on Phytophthoras in California native plant nurseries and restoration sites.

Global change is widely altering environmental conditions which makes accurately predicting species range limits across natural landscapes critical for conservation and management decisions. If climate pressures along elevation gradients influence the distribution of phenotypic and genetic variation of plant functional traits, then such trait variation may be informative of the selective mechanisms and adaptations that help define climatic niche limits. Using extensive field surveys along 16 elevation transects and a large common garden experiment, we tested whether functional trait...