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

 

Washington stream monitoring updates

The Washington State Department of Agriculture will no longer be monitoring waterways in the state as of 2012. Nursery-level monitoring required under the Confirmed Nursery Protocol will continue. Stream baiting efforts are still be conducted by the Washington Department of Natural Resources (DNR); however, with 2012 sampling having commenced in late January in 5 counties and 10 watercourses. The first (of likely six) round of samples has been retrieved for analysis. In addition to leaf baiting, DNR will be working with the USDA Forest Service on “Bottle of Bait” protocols to assay each of the streams for P. ramorum. More baiting stations will likely be added to the survey over the course of the sampling period if P. ramorum is detected at any of the sites.

from the March COMTF newsletter

Boxwood blight - a new disease

Boxwood blight, a fungal plant disease new to North America, has been detected in Oregon for the first time, prompting state officials to take measures to eradicate it. However, unlike the pathogen that causes sudden oak death, the newly-reported disease is no threat to the state’s environment and only affects boxwoods, a plant species that is not native to Oregon.

Boxwood blight, Cylindrocladium buxicola, has now been found in eight states and a Canadian province. It has previously invaded Europe and New Zealand. Boxwoods are commonly grown and sold by nurseries. The Oregon Department of Agriculture discovered boxwood blight disease at a Washington County nursery in December. ODA is working with the nursery to destroy all the infected blocks by bagging and burying the plants. The nursery is also voluntarily taking other actions to get rid of the disease.

 Read more at naturalresourcereport.com