History is Key Factor in Plant Disease Virulence

A study of P. ramorum isolated from different hosts shows changes in virulence:

"The virulence of plant-borne diseases depends on not just the particular strain of a pathogen, but on where the pathogen has been before landing in its host, according to new research results.
Scientists from the University of California System and the U.S. Department of Agriculture's Agricultural Research Service (USDA ARS) published the results today in the journal PLoS ONE.
The study demonstrates that the pattern of gene regulation--how a cell determines which genes it will encode into its structure and how it will encode them--rather than gene make-up alone affects how aggressively a microbe will behave in a plant host.
The pattern of gene regulation is formed by past environments, or by an original host plant from which the pathogen is transmitted."

Read more in the press release from the National Science Foundation

Forest Insects and Diseases Arrive in US Via Imported Plants

ScienceDaily (Apr. 9, 2012) — The trade in live plants from around the world has become a major industry in the United States, with new imports now valued at more than $500 billion annually. According to a study conducted by researchers at UC Santa Barbara's National Center for Ecological Analysis and Synthesis, however, what has proved to be a boon for the economy has also been shown to have devastating effects on the environment.

(read more)

New website about invasives

Learn about emerging invasive species (including P. ramorum) in the US at the USDA Hungry Pests site:

http://www.hungrypests.com/index.php

Increased risk of damage from Phytophthora diseases under climate change

Sudden Oak Death and other Phytophthora tree diseases are predicted to be the most damaging of all tree diseases if climate change makes conditions in Western North America wetter and warmer.  This finding is one of the conclusions from "A Risk Assessment of Climate Change and the Impact of Forest Diseases on Forest Ecosystems in the Western United States and Canada," by John Kliejunas.  Drawing on a large body of published research, the report details the effects of eight forest diseases under two climate-change scenarios – warmer and drier conditions, and warmer and wetter conditions. The likelihood and consequences of increased damage to forests from each disease as a result of climate change were analyzed and assigned a risk value of high, moderate, or low.  The risk value is based on available biological information and subjective judgment.  Free copies of the report are available via download or by mail at http://www.fs.fed.us/psw/publications/documents/psw_gtr236/.  Funded by the USDA Forest Service's Western Wildland Environmental Threat Assessment Center and the Pacific Southwest Research Station, the risk assessment was conducted as part of the Climate Change and Western Forest Diseases initiative.
Kliejunas, J.T. 2011. A risk assessment of climate change and the impact of forest diseases on forest ecosystems in the Western United States and Canada. Gen. Tech. Rep. PSW-GTR-236. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. 70 p.

From COMTF April Report

Not even celebrities are exempt

Linda McCartney memorial wood is destroyed by disease

When hundreds of trees were planted in remembrance of Linda McCartney, it was hoped that they would grow to be a living and lasting memorial to the first wife of Sir Paul McCartney.

Now, however, all the larch trees in Linda’s Wood have had to be chopped down because of a deadly disease sweeping the country.

The trees were the victim of Phytophthora ramorum, or sudden oak death, which has jumped species and is infecting other trees including larch and the Douglas fir.

Read more here - The Telegraph