#phytophthora ramorum

[aaronstjames]

Potent tree-killing disease reemerges in the Bay Area

https://www.sfchronicle.com/california/article/sudden-oak-death-trees-19925571.php

[fhithich]

Tarn Hows

A landscape under change.

If you were to look at a calendar of the Lake District, one of the months is sure to feature Tarn Hows. It is one of its most picturesque views. Yet it is entirely manmade. Until James Garth Marshall, whose father had made the family fortune from his linen mills in Leeds, began his grand design of his Monk Coniston estate. Before 1862 it had been three smallish ponds is a boggy valley, part of…

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[fhithich]

Tarn Hows

The changing character of a Lakeland beauty spot.

The National Trust has been doing a lot of felling on their Tarn Hows property opening up new vistas but this is a small consolation for the change in the character of the tarn and woods from an iconic Lakeland wooded tarn to an area resembling the aftermath of a Tunguska event. The felling is the response of an outbreak of the disease Phytophthora ramorumand trees need to be felled quickly to…

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[newstfionline]

This disease has killed a million trees in California, and scientists say it’s basically unstoppable

By Chris Mooney, Washington Post, May 2, 2016

Healthy forests are especially important at a time of climate change--they’re an incredible tool to remove carbon dioxide from the atmosphere. Dead forests, on the other hand, can light the spark for wildfires, which are already showing a long-predicted uptick in activity.

In California’s coastal forests, health is anything but good. Since 1995, a fungal pathogen that causes a phenomenon dubbed ‘sudden oak death’ (a far catchier name than that of the pathogen itself, Phytophthora ramorum) has taken out millions of oak and tanoak trees, particularly along the coast extending northward from Monterey County. That includes areas of Marin County, Sonoma County and Big Sur.

The pathogen is a fungus that affects different trees differently, and not all are susceptible. It will tear through a forest and kill some trees while leaving others standing.

But in some trees, the pathogen causes tree trunks to crack open a ‘canker’ and literally bleed out sap. The disease is actually related to the pathogen that caused the Irish potato famine in the 1800s.

“Millions of acres of land have been affected in coastal California,” says Richard Cobb, a postdoc at the University of California, Davis, who studies the disease. “It spreads via wind and rain, and it’s made some really big jumps to different parts of the state and into Oregon. It probably spread into California via the nursery trade. And it has been moved around the country a lot, also within the nursery trade.”

Unfortunately, new research on this invasive disease, published in the Proceedings of the National Academy of Sciences Monday by Cobb and a group of colleagues, finds that while there may once have been a chance to stop the spread of sudden oak death--around the year 2002--that opportunity has since passed. Forces didn’t mobilize fast enough or spend enough money, and the disease model employed in the new research (a model not so dissimilar from those used to study how various diseases can spread among humans) suggests continual spread of the disease.

“Slowing the spread of P. ramorum is now not possible, and has been impossible for a number of years,” the study states bluntly.

To stop sudden oak death, you have to go in and remove infected trees across a large area. And there’s so much pathogen mass now in California forests that the model finds that it will just spread, and spread. As pathogen biomass increases, says Cobb, “the rates of spread accelerate, and so does cost.”

More specifically, the study found that unchecked, sudden oak death will grow to affect close to ten times the current area--from around 1,550 square kilometers today to 14,000 square kilometers by 2030. But it also found that an attempt to manage the problem by removing infected trees over 200 square kilometers annually, at a cost of $ 100 million, would make little dent in this spread.

Simply put, the disease is now in a “phase 3 epidemiological state, the study says, in which “the pathogen has spread far enough that eradication is no longer possible; local containment may still be an option.”

“Our analyses show that statewide action to eradicate or even slow the spread of [the pathogen] is no longer feasible, even with a substantial budget, indicating that the epidemic in CA is now firmly in phase 3,” the study continues.

Granted, it’s not like stopping the disease in 2002 would have been easy. “It would have taken unprecedented cooperation, and an unprecedented amount of funding,” says Cobb. “This would have been extremely difficult and there would be some tough questions about whether it would be worth, even then, such a huge investment.” He suggests the cost could have been $60 million per year, for many years.

Instead, though, California must now live with the impacts of the disease. They include forest areas filled with dead trees that are a fire risk--and a risk not only of burning themselves, but also carrying fire to other trees that are still living and did not get infected with the pathogen, Cobb says.

The sweeping disease underscores just how disruptive and unpredictable invasive species threats can be--from the mosquitoes that carry Zika to plant pathogens--at a time of unprecedented global trade and travel, combined with climate change.

“It was known as this minor pathogen of Rhododendron in the Netherlands prior to arrival in California,” says Cobb. “Given the state of knowledge about the thing, there is nothing where you would have said, ‘oh, this is going to be a problem in California oak forests.’ We’re constantly caught off guard by these things, they seem to frequently behave in ways that we don’t anticipate.”

[photohall]

Globalisation is killing our trees as the volume and speed of international trade and human movement increases.

These pictures dating back to 2007 are from Gougane Barra in West Cork where approx 16,000 trees have just been felled. This action is yet another example of Mans Grandiose delusions 'of having a special relationship with God' meaning that we can somehow control nature and exploit Earths resources without consequence. The beauty of this place has now been lost for the next couple of generations which in the context of my life seems totally devastating but the trees will return.

What's the most worrying aspect of this event and others around the world is how Man has continued to endanger the earths trees, woodlands and ecosystems in such a short time. Trees have evolved over the past 300+ million years predating Dinosaurs by some 60 million years however in the last 250 years Man has spread the following diseases and pests. It is only a matter of time before the last few remaining threats not yet present in the British Isles become established.  Diseases • Acute oak decline • Chalara dieback of ash • Chestnut blight • Dothistroma needle blight • Dutch elm disease • Phytophthora alni • Phytophthora austrocedrae • Phytophthora kernoviae • Phytophthora lateralis • Phytophthora ramorum Pests • Asian longhorn beetle • Great spruce bark beetle • Horse chestnut leaf miner • Oak pinhole borer • Oak processionary moth • Pine tree lappet moth Phytophthora ramorum (P. ramorum) is a fungus-like pathogen which causes extensive damage and mortality to a wide range of trees and other plants. Also known as 'sudden oak death' USA, 'Larch tree disease' and 'Japanese larch disease' in Europe. P. ramorum has been found on nursery stock in a number of other European countries including Belgium, the Czech Republic, Netherlands, Denmark, France, Ireland, Italy, Spain (including the Balearics), Slovenia, and Sweden. The globalisation of tree diseases is not new. When international trade increased exponentially in the 19th century, the spread of tree blights followed. In the early 20th century, rich countries instituted biosecurity regimes and the incidence slowed. Across Europe, the infection rate picked up around 1960, most likely due to the effect of economic integration. Today, the spread of new pests and pathogens around the world is gathering pace again, as the volume and speed of international trade and human movement increases. In Britain, a pathogen which has killed millions of trees in Germany is infecting our native alders. Horse chestnuts are at risk from a deadly bleeding canker. Massaria disease, caused by a fungus, has reached our shores and is affecting London Plane trees. Thousands of acres of larch have been felled across western Britain because of infection from the fungus-like Phytophthora ramorum pathogen. Our oaks are suffering from the oak processionary moth. Red-band needle blight is a fungus affecting Corsican pines. In 2011, sweet-chestnut blight caused by the fungus Endothia parasitica arrived in Britain, some 80 years after it devastated the trees of southern Europe. The list goes on. It seems a new blight is identified in Britain's woods almost every year. By the time these pests and pathogens have reached the UK, the battle has largely been lost. What we need to do in the future is prevent yet more plant diseases reaching this country through trade controls, quarantining and clear supply chains.

Source: Independent UK, Coillte Ireland, Forestry Commission England & my opinion.