Sudden Oak Death

[KeyserXSoze]

http://www.newscientist.com/news/news.jsp?id=ns99994457

Deadly fungus disease hits UK trees

18:32 05 December 03

A strain of fungus that has decimated California's oaks has been confirmed in four trees in England, the UK government is warning.

Government authorities are scrambling to learn how to contain the deadly plant disease, nicknamed "Sudden Oak Death". The appearance of the fungus in a handful of UK trees is evoking memories Dutch elm disease, which wiped out 20 million of UK's 30 million elms in the 1960s.

A North American strain of the fungus (Phytophthora ramorum) has killed 80 percent of California's tanoak trees.

"At this stage, we are unsure of the implications of this ramorum disease for our native tress," says Ben Bradshaw, minister for nature conservation. "These findings are a matter of concern and we urgently need to assess, with the relevant expert groups, the best way forward to limit the disease's impact."

Chris Prior, head of horticultural sciences at the Royal Horticultural Society, cautions: "We hardly know the fungus's full host range, so the potential level of damage is much wider. We're faced with a worrying scenario."

The North American strain is known to infect about 20 plant species, although the severity of its effect varies by species.

Flowering shrubs

Sudden Oak Death, which is related to the pathogen responsible for Ireland's devastating potato blight in the mid-1800s, swept through California's oaks in the 1990s.

The first symptoms of the European strain were spotted in Germany and the Netherlands in 1993 but were restricted to the flowering shrubs rhododendron and viburnum. More than 360 of these plants have been diagnosed with the fungus in the UK since April 2002, although most of those cases were in nurseries.

These same shrubs surrounded all of the four known contaminated trees, boosting theories that the disease was imported from nurseries in northern Europe and can spread through shared groundwater. Resting spores in this species also may transport the fungus through soil.

Prior says the Sudden Oak Death moniker is misleading as trees other than oak are vulnerable. "We're more worried about things like beech, which we suspect will be more susceptible," he says

Bleeding canker

The confirmed infections occurred in Sussex and Cornwall in four different species: southern red oak, beech, horse chestnut, and holm oak.

Symptoms vary depending on the infected species. For example, in the infected beech a 'bleeding canker' is oozing liquid from a spot on the bark where the fungus entered the tree. Prior says the tree will probably die.

"There's not going to be a cure in the sense of a magic bullet," says Prior. Injections of fungicides can provide temporary relief of symptoms, he says, "but if the disease becomes established in the UK, treating acres of trees is not an option."

Prior adds that recent reports of European strains being found in the US and vice versa are disturbing. These strains are normally forced to reproduce asexually - producing clones. But with cross-contamination, the fungus can now reproduce sexually which could boost its virulence, he warns.

 

[Anonymous]

Extremely worrying.

I've been a member of the Woodland Trust for quite a few years, and have planted not a few trees myself. British broadleaved woodland, especially ancient woodland, is extraordinarily rich in wildlife and genetic diversity. It is also most beautiful, and a vital part of our national heritage.
We've already lost such a lot to development. Dutch elm disease, the drought of '76, and the hurricane of '87 took their toll also. I'm not an expert on what can be done in this type of situation, but I guess maybe some form of containment? It's very worrying especially if more than one species is affected.

Big Bill Robinson

 

[Breakfastologist]

From what I read elsewhere about it Rhodedendron appears to be a possible vector - it maybe that infestations of that will have to be cleared (no bad thing in many cases) to protect the surrounding forest.

 

[Anonymous]

It's a shame that the landscaper companies that import the non-native plants that are resistant to these diseases don't think about the fact that the native plants might not be so lucky. Here in California and also in Arizona there is a lot of concern about non-native landscaping plants that have dormant fungi or viruses, which the host plants shrug off...but the native species are very very vulnerable to. Apparently you can import almost any plants as long as you can demonstrate them to be free of insects. But the imported plants can carry disease in a dormant stage, and they can also overtake a native plant habitat in a way that is very damaging to the environment. Kudzu in the south (brought in to check erosion, took over vast areas) and cape and english ivy in the Bay Area are two that come to mind.

 

[Anonymous]

Here in BC we have a very scary problem of the Chinese mountain pine beetle killing forests from Yukon to the US border. The beetle has already destroyed 4.2 million hectares and keeps spreading as quickly. One can fly for hours and see unending huge red zones of dead forest. The only solution would be a week or two of -40 degree weather to kill them all but the climate has become too warm - even in northern Canada...

http://www.canada.com/search/story.aspx?id=646e1746-a7de-40a8-8739-b7bf4be558a8

 

[TheQuixote]

Has tree disease spread?

Red oak shows signs of California malady

By Patrick Healy
The New York Times


OYSTER BAY COVE, N.Y. -- A botanical mystery is playing out at the Tiffany Creek Nature Preserve, here amid rolling hills and sprawling Long Island estates. A single red oak tree at the preserve has tested positive for sudden oak death syndrome, a disease that ravaged forests in California, and scientists are trying to figure out whether the infection is a dire beginning or a false alarm.

Scientists with the U.S. Forest Service and the Department of Agriculture are equally baffled and worried. Sudden oak death syndrome has killed tens of thousands of trees and cost governments and plant nurseries millions of dollars, but until now, it has only been found in trees in Northern California and southern Oregon.

A knotty red oak tree standing in the preserve first tested positive for the disease last month, and scientists said Wednesday that they were running a battery of secondary DNA tests on tree samples to determine whether the tree truly carries the debilitating bug. Tests on trees in Pennsylvania and New Hampshire have yielded false positive results before, said Kerry Britton, a pathologist for the Forest Service.

"I'm still hoarding the hopes that it's not really there," Britton said. "If it is a positive, they'll have to declare a quarantine zone around the area and declare an eradication effort. They'll have to cut down that tree and trees around there. It's up to the state to decide how drastically."

Environmental officials throughout the Midwest and the East Coast have feared an outbreak of sudden oak death syndrome ever since trees in California began dying from the disease in the mid-1990s.

A fungus-like pathogen called Phytophthora ramorum hops from plant to plant by riding rivulets of windblown rain, scientists said. It can lay dormant in trees for years, and then kill them within weeks. Oaks are not the only trees affected. The disease has killed more than a dozen species of trees on the West Coast, and has prompted quarantines of potentially infected plants from California.

Steven Swain, a researcher at the University of California at Berkeley, who has studied the disease, said early tests on East Coast oaks have shown them to be more vulnerable to the disease than trees in the West.

"If this gets loose on the East Coast, it could cause quite a bit of damage," Swain said.

No other trees, ferns or plants in the Tiffany Creek preserve have tested positive for the disease.

Scientists took 60 other samples from the suspect red oak and tested any tree within 20 acres that showed a passing sign of illness, officials with the inspection service said. They expect the test results next week.

L.A. Daily News.com