Deadly oak disease hits Welsh private woodland


An outbreak of the pathogen Phytophthora ramorum, otherwise known as sudden oak death, has been discovered for the first time in Wales on trees in a privately-owned woodland, reports the Forestry Commission Wales.

Staff from Forestry Commission Wales and the Food & Environment Research Agency (Fera) have visited the owner of the woodland in Denbighshire and a notice has been served to fell the infected Japanese larch trees. Only a small number of trees are infected, and the owner will use the timber on site.

Sudden oak death is a fungus pathogen that kills many of the trees that it infects. It was first found on Japanese larch trees in Wales in June this year in public woodlands  near Port Talbot, near Bridgend.

The outbreak in South Wales was the first time P. ramorum has been encountered on larch elsewhere in Great Britain since it was first discovered on larch in South-West England in 2009.

The woodland owner, Wendy Charles-Warner, contacted Take Cover, to say: “We feel rather aggrieved at the tone of the [Forestry Commission] press releases stating that we have been served with enforcement notices as if we were responsible for this outbreak and somehow in the wrong.

“We could take no steps to prevent this disease which is mainly airborne, have done nothing wrong and have at every point done everything we can to assist the forestry commission.”

A motor rally set to attract thousands of spectators to South Wales in July was postponed as a result of an ou6tbreak of the tree disease.

The route of the Swansea Bay Rally ran through forests that had been hit by the infection.

Richard Siddons from the Forestry Commission Wales said the organisation was “determined to minimise the impacts of this serious tree disease on woodlands, and the support of woodland owners in looking out for early signs of P. ramorum infection will play a key part in achieving that”.

It seems as if the warm but wet summer has been a key driver in the development of tree pathogens, with a number of cases making the headlines.

In April, a group of woodland experts expressed their fears for the future of British native oaks in light of the emergence of a disease called Acute Oak Decline, a bacterial infection that, they warned, could be as devastating for the English Landscape as Dutch elm disease in the 1970s.

They called for much more financial support from the UK government to help tackle the problem through research and land management measures.

In July, the Forestry Commission announced a £600,000 support package for woodland owners in South-West England and Wales to help tackle the outbreak of P. ramorum infection on larch trees. The package is part of Defra’s £25 million, five-year Phytophthora management programme.

Forestry Commission Wales is developing a complementary programme of support for private woodland owners who have P. ramorum confirmed on their land. Details of this support will be announced in September.

Ms Charles-Warner, in her comment to the story on this blog (see below for her full response), added: “

The ‘package of assistance’ that the Commission have announced is £300 per hectare, which we are not receiving or going to receive.

“If you have knowledge of tree felling you will appreciate that in a situation where stringent biosecurity measures have to be used and the trees have to be felled and brashed by hand that is a paltry sum, even in the highly unlikely event that you receive it.

She went on to say that she was “deeply concerned” about the situation: “If the Commission wishes landowners to report Phytopthora Ramorum and control it, in order to protect commercial forestry, then realistic support needs to be in place.

“Many landowners faced with a the prospect of funding felling and site clearance work themselves with the attendant stress and unpleasantness, are likely to ignore the disease and not report it.”

More information about sudden oak death can be found on the Forestry Commission’s website at www.forestry.gov.uk/pramorum.

To find out more about the support fund or to report suspected P. ramorum infection in their trees, woodland owners should contact Forestry Commission Wales’s Grants & Regulations Office on tel: 0300 068 0300 or email: bww.ts@forestry.gsi.gov.uk.

Source: Forestry Commission Wales press release

Date: 25/08/2010

UK elms – ‘not out of the woods yet’


Colin Tudge, the author of The Secret Life of Trees, is invited by the UK’s Telegraph newspaper to give his reaction to efforts to breed a Dutch elm disease-resistant species.

Library image from Take CoverIt’s an interesting read as he gives his reaction to this battle with nature, so here it is:

Could the English elm, so sadly laid low by Dutch elm disease, make a comeback? Paul King, who breeds trees at Raine in Essex, is on the case. Nearly 25 years ago he acquired cuttings from a few mature trees. He has now multiplied the tissues to produce a whole new generation of young elms that seem to be resistant (and are on sale for £120 apiece). Scientists at the Forestry Commission’s research centre in Surrey welcome his initiative – they are on the case, too – but are cautious. Resistance, they point out, is a tricky business.

The English elm, Ulmus procera, is probably not a “true” native – Britain has only 39 “truly” native trees – and was most likely introduced by Neolithic farmers from south-east Europe, via Spain. But it is an honorary citizen, treasured for its usefulness and its looks, favourite of landscape painters, notably of Constable; a tree of open woodland but just as happy in hedgerows where, if it was left alone, it flourished by the tens of millions. In the West Country it was known as “the Wiltshire weed”.

The first sign of trouble came in 1910 when the fungus Ophiostoma ulmi, a distant and degenerate cousin of the truffle, started killing trees in mainland Europe. It acquired its name, Dutch elm disease, in 1921 because it was first properly researched in Holland. It arrived in Britain by 1927 and looked very nasty. Happily, the disease died down by the Forties, after killing 10 to 40 per cent of our elms. Dr Tom Pearce of the Forestry Commission predicted, in 1960, that such a thing should not happen again – unless, he added, “the fungus completely changes its present trend of behaviour”.

Which it duly did. A new, closely related species of Ophiostoma appeared in North America – Ophiostoma novo-ulmi. It arrived in Britain in 1967 on imported logs, and throughout the Seventies and into the Eighties it killed about 25 million out of about 30 million elms, including most of the particular English species, Ulmus procera.

Dutch elm disease has all the biological attributes needed to be thoroughly nasty. It is one of the many “wilt diseases” of trees, which spread through the vessels of the xylem and block them. The spores are carried passively with wonderful efficiency in the sap, through the whole tree, and spread via the roots of separate trees that are often joined underground. The spores don’t live long once the tree has died and so should die out as their host succumbs – but they have a trump card: they are carried from tree to tree and from forest to forest by flying bark beetles of the genus Scolytus.

There is some innate resistance among the world’s many species of elm. The Ophiostoma fungus probably arose in Asia, so the Asian elms have evolved in its presence – and have developed considerable resistance. Breeding programmes are afoot in Europe to introduce genes from Asian species into European types by various means – and may yet succeed. Meanwhile, as Paul King has found, even within susceptible species, such as Ulmus procera, there will usually be some resistant strains. If they can be bred, perhaps we will have a new resistant strain.

So why the caution? Well, for one thing, it depends what the tree is really resistant to: the fungus or its insect vector? Paul King’s new trees are probably not resistant to the fungus itself, but are simply less palatable to the beetle. Of course, the fungus can’t usually infest the tree without the beetles – but it surely would be better to be specifically equipped with genes that would protect it even if beetles did get in.

The sad tale of Britain’s elms parallels that of the American chestnut, Castanea dentata – with some intriguing contrasts. For the American Indians and for the first immigrant Europeans, the American chestnut was a wonder tree. Its nuts were a food staple – and supported 40 million wild turkeys for good measure – and its trunks provided timber. There were so many that a squirrel could travel from chestnut to chestnut from Maine to Georgia without setting foot on the ground, or so the story went.

But the overconfident forestry “improvers” of the 19th century were still not content. They began to import Asian species with bigger nuts, to crossbreed. Inevitably, the newcomers came with their own diseases. And the American chestnuts, beset by novel pathogens, succumbed. By the end of the Twenties, the American chestnut, once perhaps the commonest North American broadleaf, was all but gone.

Again, through too much zeal, the Americans felled great swathes of chestnuts to create a firewall against the spread of infection. This failed to contain the disease – but it did, so some biologists suggest, remove the myriad genetic variations from among the wild trees, which might have included some that would have conferred resistance.

By leaving our own beleaguered elms to live on in the hedges, and nurturing the few survivors, as Paul King and others have been doing, we may avoid that final fate. (In truth, the American chestnut might not quite be dead. At least, George W Bush planted one outside the White House on Arbor Day in 2005 – but it is a hybrid: 15 per cent of its genes are from resistant Asian species. It is a sad relic, like an exhumed dodo).

Overall, the message is mixed. We could see the heroic efforts of a few growers and scientists as a triumph of human ingenuity over natural adversity – the continuing tale of “man’s conquest of nature”. Or we could see this endeavour as a desperate, last-ditch attempt to ward off the consequences of our own folly. For these are tales of hubris. We thought we could do what we liked in the name of commerce. But actually, life is more complicated than we ever supposed – and in the end, it is beyond our ken. Cause and effect relationships in nature are non-linear, which means it is intrinsically impossible to predict the outcome, beyond saying it won’t be good.

Source: Telegraph newspaper

Date: 09/06/2010

Forest Research draws up canker plan


Forest Research is to develop guidance on managing and drawing up controlling strategies for the bleeding canker tree blight, reports Horticulture Week.

“This disease has rapidly become widespread throughout Britain over the past five years,” said a representative for the research arm of the Forestry Commission.

Bleeding canker of horse chestnut was caused by the bacterium Pseudomonas syringae pv aesculi (Psa), but until recently it had only been reported in India in 1980, he said.

“It has now proved to be highly mobile and exceptionally virulent to European horse chestnut, Aesculus hippocastanum.”

Researchers were looking to provide an accurate diagnosis of the pathogen and underpin management strategies to combat the disease.

“A technique called real-time polymerase chain reaction has been developed and is being used to detect the levels of Psa on infected trees and their surroundings.”

Previously little was known about what natural resistance horse chestnut populations may have had to Psa.

“But evidence indicates that even in heavily affected locations some trees remain healthy and symptom-free.

“Disease-free horse chestnuts have been propagated and will be tested for disease resistance in inoculation trials and compared against other disease-prone individuals.

“This research will ultimately guide management and mitigation strategies. Molecular techniques developed will also be applicable to the study of other important tree diseases.”

Source: Horticulture Week

Date: 07/05/2009

Planting trees amid chaos of war


In the Tree Garden of Kilravock Castle is what looks like a giant octopus, says Steven McKenzie, a reporter for the BBC News website.

Called a layering beech, its limbs snake out from a sturdy trunk and bend to the ground where they have taken root before twisting skywards.

More than 300-years-old, it is classed as “extremely rare” in the Forestry Commission‘s list of Heritage Trees.

It would have been relatively young at the time Bonnie Prince Charlie visited the castle in the days before the Battle of Culloden.

The castle and its grounds lie a few miles east of Culloden Moor.

In a bizarre twist, Hugh Rose, the 17th Baron of Kilravock, played host to the warring cousins Charles Edward Stuart – Bonnie Prince Charlie – and the Duke of Cumberland in the days before the Battle of Culloden.

According to the Genealogical Deduction of the Family of Rose of Kilravock by Rev Hugh Rose, a book later updated by historians Lachlan Shaw and Cosmo Innes, the Young Pretender stopped at the castle as his forces massed in the surrounding countryside.

The baron, who is thought to have had no role in the later fighting, played the prince’s favourite Italian minuet on a violin before showing him his tree planting operations.

Bonnie Prince Charlie was said to have remarked: “How happy are you, Mr Rose, who can enjoy these peaceful occupations when the country round is so disturbed.”

The following day – 15 April – the Duke of Cumberland headed for the castle, according to the genealogical deduction.

The book goes on to tell how the baron feared reprisals for hosting the Jacobite figurehead, but was told by the duke he could not have refused hospitality and had no choice but to treat him like a prince.

Kilravock Wood also played a part in the downfall of the Jacobite night march, according to historian Christopher Duffy’s recent book The ’45.

Soldiers were delayed as they negotiated a breach in a wall around the woodland and elements became lost among the trees.

Nicole Deufel, learning manager at the National Trust for Scotland’s Culloden Battlefield Visitor Centre, said the night march was recognised as one of many factors influencing the outcome of the Battle of Culloden.

She said: “The main problem was that the men were exhausted even before they set off on the night march. Some drifted away looking for food and sleep.

“The story goes that, on their return, Prince Charles only slept for an hour and there was just one biscuit per man for food.”

On whether the march could have succeeded, she said: “It’s hard to say. There probably would have been another battle after this.

“A successful night march would not have prevented another battle in the future, but there may not have been a Battle of Culloden.”

Source: BBC News website

Date: 20/03/2009

Welsh woodlands to fight climate change


Climate change experts from across Europe will be seeing how the Welsh woodlands are already helping to alleviate the effects of climate change, says a press release from the UK Forestry Commission.

Researchers in Wales are putting in place exciting new ways in which the forests can help prevent flooding as well as locking away millions of tons of carbon dioxide.

Leading members of the new FUTUREforest project will be taken on a fact-finding tour of south Wales on 26-27 March, 2009.

The mission is part of the project’s remit to share experiences and new methods of environmental management to prepare the forests of Europe for climate change.

Specialists from the other six partner regions – Auvergne, France (biodiversity); Brandenburg, Germany (knowledge transfer); Bulgaria (soil protection); Catalonia (natural risks); Latvia (timber production); Slovakia (carbon sequestration) will see some of the effects of climate change on Welsh forests – and some of the solutions in and around Abergavenny.

They will see how woody debris dams, new woodland creation and other flood risk management techniques in the uplands can help to prevent the kind of flooding that has caused millions of pounds worth of damage across Wales.

The 30 strong delegation will be staying at The Hill Education & Conference Centre, Abergavenny, and visiting Forestry Commission Wales woodland sites at Mynydd Du, Usk College and the Woodland Trust’s Great Triley Wood.

“We have already begun to discover much about the way the woodlands of Europe can help us to combat climate change,” said Mike Over, Project Manager of the FUTUREforest project in Wales.

“We hope that experts from our partner regions discover that in Wales we have made some really exciting new discoveries that can help them back in their own countries.”

Source: Forestry Commission press release

Date: 19/03/2009

Bleeding cankers continues to take its toll


The avenue of 43 horse chestnut trees at Barrington Court, near Ilminster, in Somerset is being cut down and replaced with a variety of oak, the Telegraph reports.

The National Trust decided the trees had do go for safety reasons, following an infection of bleeding canker that causes the trees to lose bark and branches and eventually die.

The Trust has already had to cull a number of other horse chestnuts at properties around the country, with 28 trees recently chopped down in Avebury, Wiltshire.

Home-owners around the country have also had to cut down horse chestnuts because of the disease, which the Forestry Commission say has killed 3,000 tree in recent years.

The disease is spread by spores in the ground and can cause the tree to bleed a reddish brown liquid. It can be controlled by cutting out infected areas but will eventually kill the tree.

Christine Brain, head gardener at Barrington Court, said: “Bleeding canker is rife in England’s horse chestnuts.

“It kills the tree from the inside out, and while doing so makes it susceptible to other infections which hasten the trees death.

“We’ve been maintaining the trees over the last few years in an effort to extend their life and keep the disease as controlled as possible, but removal is now our only sensible option.”

Horticulturalists have warned that conker trees are in danger of dying out in Britain unless more is done to control the disease.

The call comes as the UK government announced a £25m package to curb the spread of sudden oak death through woodlands in England, Wales and Scotland.

Source: Telegraph newspaper

Date: 03/03/2009


Twiglet: Trees and roots


  • First thing to emerge from a seed is the embryonic root – the radicle.
  • In most plants, this primary root will develop secondary or lateral roots that grow out away from the main root as the plant grows.
  • The growth of any root is dependent on a small ball of dividing cells just behind the root tip. This collection of cells is called a meristem; it generates new cells to extend the root and form new root tissue (such as the xylem and phloem – the conducting tissues).
  • A long tap root may develop in suitable soils, whilst, in sandy ot peaty soils, the lateral roots may dominate.
  • Studies indicate the dominance of the young tap root is often lost quite early in development in many tree species.
  • The deepest root systems are probably found on desert plants.
  • Tree roots do not generally occur too deep in the soil, with the majority of roots found in the top one to two metres.
  • Trees tend to have shallow but extensive root systems.
  • The spread of the lateral roots can be as great as the spread of the canopy or crown, even further in some cases.
  • One study showed that the root spread of poplars was three times the crown radius. This type of root system is sometimes referred to as an extensive system.
  • An intensive root system is one that is confined to a smaller volume of soil, relying on shorter lateral that have numerous fine endings. This system is seen in beech (Fagus sylvatica), which was one of the species that suffered more than most in the drought of 1976.
  • The survey of trees blown over in the October 1987 Great Storm showed that only 2-3% had distinct tap roots.
  • Oak, pine and silver fir are among the species with persistent tap roots.
  • Other species have what are known as “heart root systems”, where larger and smaller roots penetrate the soil diagonally from the main trunk. Trees such as larch, lime and birch can fall into this category.
  • A surface root system is one where the roots tend to run horizontally just below the soil surface, with a few roots going deeper and vertically. Ash, aspen and Norway spruce are examples of trees with these kinds of roots.
  • The root system depends upon the local geology, soil type, climate, drainage… so, if a local area is water logged, this will limit the gas exchange which in turn will affect the amount of oxygen the roots can get for respiration (which generates the energy needed for growth and the absorption of minerals).
  • When oxygen levels in the soil falls, root growth is reduced or stops completely — the availability of oxygen can also be reduced by the compaction of the soil.

Source: Woodland Trust

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