Dutch elm disease ‘resistant’ trees go on sale


More than 2,000 healthy English elms have been produced from a single tree which survived the devastating disease in the 1970s, the UK’s Telegraph newspaper reports.

Take Cover library imagePaul King, who runs a tree nursery, stumbled upon the mysteriously unharmed specimen while he worked to clear hundreds of diseased elms and took cuttings from it.

Over the next 23 years, the paper says, he used the samples to nurture hundreds of saplings which have the same resistant traits as the 200-year-old parent tree.

Mr King sent the sample plant tissue off to a laboratory for micropropagation.

Now, nearly 25 years later, the cuttings have produced 2,000 healthy trees which are set to replace the dwindling English elm population.

The trees (Ulmus procera) are believed to repel the beetle which carries the Dutch Elm disease.

The 10ft tall trees are available to buy from Mr King’s business, The Tree Nursery in Rayne, Essex, and cost £120 each.

Mr King said: “We have been working hard on the project for 23 years.

“I was working dismantling and clearing diseased elms when Dutch Elm disease hit, and saw how many were destroyed.

“But as we worked in this particular area, we noticed that there were a few trees which seemed to be resistant to the disease.

“While other trees around them died, these were totally unharmed by the Dutch Elm disease.

“After about 10 years, they were still surviving while every other tree in the area had died and we knew they must be resistant.

“So an expert from the local council took cuttings from one of the mature trees for me, which survived – and then kept surviving.

“We realised we had something on our hands here and I sent them off for micropropagation, and before I knew it I had a production.

“The original trees, which are around 150 to 200 years old, are still surviving less than five miles from the nursery and the first cuttings are still 100% in leaf.

“The trees we have propagated are all still in full leaf, even though there is Dutch Elm disease in the hedges just two or three metres from them.

“We can say they are extremely resistant to Dutch Elm disease.”

Dutch Elm Disease is native to Asia but was accidentally introduced in Europe in 1910, although it only killed a small proportion of trees.

It gets it name after it was isolated in Holland in 1921.

It had largely died out by 1940 but in 1967 a new and deadlier strain of the disease arrived in Britain on a shipment of elm tree logs from North America.

The disease killed an estimated 25 million elm trees throughout the UK.

Source: Telegraph newspaper

Date: 07/06/2010

Oak disease ‘threatens British landscape’


The continuing spread of a deadly disease that affects the UK’s native oak trees is causing concern among tree professionals and conservation groups.

Take Cover library photoThe BBC’s environment reporter Mark Kinver writes that Acute Oak Decline (AOD), caused by a bacterial infection, can kill an infected tree in just a few years.

Some tree experts are comparing AOD to Dutch elm disease, which killed millions of trees throughout the UK during the 1970-80s.

They said extra funds for more research into the disease were urgently needed.

Although AOD has been confirmed in 55 cases, the number of trees displaying symptoms was steadily increasing, delegates at the Royal Forestry Society’s (RFS) annual conference were told.

The disease affects the UK’s two native species of oak – sessile and pedunculate. To date, there have been no confirmed cases in other species of oaks found in Britain, such as Turkey and red oaks.

‘Extensive bleeding’

Information from Forest Research, the scientific department of the UK Forestry Commission, says the new disease affects oaks more than 50 years old.

Symptoms are “extensive stem bleeding” in which dark fluid seeps from small cracks in the bark and runs down the tree trunk.

In early stages of the disease, the health of a tree’s canopy does not appear to be affected, but it may become thinner as the tree succumbs to AOD.

On its website, Forest Research says: “The incidence of AOD in Britain is unquantified at this stage, but estimates put the figure at a few thousand affected trees.

“The condition appears to be most prevalent in the Midlands and investigations to determine the extent of the disorder are under way.”

A spokesman told BBC News: “Forest Research pathologists have isolated a previously unidentified bacterium they believe is highly likely to be playing a key role in the Acute Oak Decline observed in Leicestershire and elsewhere.

“However, the full cause of the condition is thought likely to be complex, involving a number of factors besides the bacterium. A research report is currently awaiting peer review.”

‘Major threat’

Tree organisations are calling for more funding to be made available to allow researchers to better understand the full impact of the disease.

John Jackson, the organiser of the RFS’s conference, said: “Urgent action is not an option – it’s a necessity.”

Hilary Allison, policy director for the Woodland Trust, added: “The impact of the loss of an iconic tree both from our countryside and towns would be catastrophic, and therefore has the capacity to be a major threat to the UK’s oak woods.”

“I have never seen anything like it,” said Peter Goodwin, co-founder of Woodland Heritage.

“Its spread over the last two years has been quite alarming.”

Mr Goodwin told BBC News that very little was known about the virulent bacteria responsible for the disease.

“We’ve never had a bacterium that is capable of doing what this one is doing.”

He suggested that people were possibly the main way in which the disease was spread from tree to tree, but added that “natural vectors” – such as squirrels, birds and insects – could also play a role.

“I think this is the worrying thing, we all want to know what are the vectors that is spreading it. Is it airborne? We just don’t know.”

Forest Research advises people working in affected areas to take appropriate measures to limit the chances of AOD being carried to new sites.

“The most important thing we can do in this and other cases is to research and understand the causes so that we can provide appropriate management advice for tree owners and woodland managers,” the spokesman added.

“It is also important that we remain vigilant against accidentally importing new and damaging pests and diseases from outside Great Britain.”

Source: BBC News website

Date: 28/04/10

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

Date palm disease threatens livelihoods in Yemen


A disease which kills date palm trees, on which thousands of people depend for a living, has returned to Hadhramaut Governorate in southern Yemen, reports the UN news service IRIN.

Khalid Saleh, 55, could not believe his eyes when he saw his smallholding in Doan District (some 250km north of Mukalla) hit yet again by the dubas bug.

In the past the disease ravaged date palms in his village leaving dozens of trees dead and spoiling the date crop for the following three years.

“In 2005, 2006 and 2007 the date crop was severely damaged by dubas and consequently many people in my village went bankrupt,” Saleh said.

“The reappearance of the disease means we’ll get a poor crop. We celebrated when heavy rain washed the trees and we thought the disease had been wiped out.”

Ommatissus binotatus lybicus De Berg, or date palm dubas, is caused by an insect which absorbs the plant’s natural juices and exudes a sticky liquid, which gradually spreads and in the worst cases engulfs the whole tree, which then dies.

Saleh Ahmed is the head of Wadi Gozah Agricultural Association, an NGO working to maintain date palms in Doan District (250km north of Mukalla), and a member of the local council.

He told IRIN that when the disease reappeared in his village, he immediately informed the Centre for Agricultural Research (CAR) in Mukalla which carries out spraying campaigns, but he was stunned by their reply.

“They told us that they didn’t have money and when they got it they would start spraying. The disease has spread wildly and they haven’t come yet,” he said.

Ahmed has warned that many people in Doan District are threatened by bankruptcy.

“Selling dates is a life-line for poor farmers; others get work tending to the trees. This year, they may fall on hard times again,” he said, adding that farmers were no longer interested in planting palm trees.

Mohammmed Hubaishan, a CAR entomologist responsible for spraying campaigns, told IRIN that lack of cash was hampering the CAR: “We don’t have enough money to combat the disease in all areas and we are also waiting for insecticide to be sent from the capital.”

Hubaishan said the disease had struck to varying degrees in different parts of the governorate, with Doan, Al-Duais, Al-Shargiah, Qusiar and Hadhramaut Valley worst affected. Hundreds of thousands of palm trees already had the disease in the valley.

“Hundreds of tonnes of the crop were afflicted by the sticky substance in the last couple of years… and packing factories were paying lower and lower prices.

According to Hubaishan, there are no precise statistics but he believes the number of trees affected could be millions, and that thousands of livelihoods are at risk.

Source: UN IRIN service

Date: 10/05/2009

Old elm ‘may help save other trees’


Experts hope an elm tree that survived the ravages of Dutch elm disease could hold the key to the species survival in the UK, the BBC News website reports.

The elm was discovered in a Worcestershire hedgerow, near Pershore, two years ago.

It had remained unnoticed because it was assumed all elms in the area had been wiped out by the disease.

The condition, which is carried by a bark beetle, has affected more than 20 million elm trees in the UK since 1970.

Now, Pershore College has taken cuttings from the newly discovered tree and has just planted the first of them.

Bob Hares, from the college, which specialises in horticulture, said that growing cuttings from old trees was difficult.

“The idea is usually to take cuttings from the young trees, which root much more readily, and build up from there,” he said.

The team will not know if these cuttings have the resistance of what they call the “mother tree” until they are about 10 to 15 years old, but they are hopeful.

Now the search is on for other elms that have survived and may also be resistant to Dutch elm disease.

The biggest problem for the college’s team is that most of us do not know what an elm looks like.

John Clarke works for Kemerton Conservation Trust, which works to preserve the natural landscape of Herefordshire, Worcestershire and Gloucestershire.

He said it would be mostly people older than 40 who would be able to recognise elms, “especially people who know trees like farmers and naturalists”.

Elms were once known as the “weed of Worcestershire”. The hope is there are more survivor trees out there to rebuild this much missed part of our landscape.

Anyone who sees a mature elmin the area is urged to contact the conservation trust.

Source: BBC News website

Date: 06/03/2009

Battle on to save Scotland’s red squirrels


More than £1m is to be spent over the next three years on saving Scotland’s red squirrels and protecting routes into their northern strongholds, the BBC News website reports.

The number or reds has been in decline since the arrival of the grey squirrel from North America in the 19th Century.

Greys compete with reds for food and can also carry the squirrel pox virus, which can kills reds in about 14 days.

There are currently about 121,000 red squirrels in Scotland and the country is home to 75% of the UK’s reds.

There are thought to be between 200,000 and 300,000 greys in Scotland.

The £1.3m Saving Scotland’s Red Squirrels (SSRS) project is being launched in Dunkeld, Perthshire.

See a map of shifting red and grey squirrel territories

It will develop habitats in which the red squirrel can flourish but will also try to control the greys, which will involve killing them.

The Scottish Wildlife Trust (SWT), Scottish Natural Heritage (SNH), Forestry Commission Scotland (FCS), and the Scottish Rural Property and Business Association (SRPBA) are involved in the project.

Environment Minister Mike Russell said: “The red squirrel is one of our most beautiful and valuable native species. Therefore its loss would be absolutely unforgiveable.

“Saving Scotland’s Red Squirrels is a true partnership organisation and I am hopeful that its activity will see the red squirrels able to thrive once again in this country and ensure that future generations are able to enjoy them.”

Ron McDonald, from SNH, said that grey squirrel control would be focussed on the key routes being used by grey squirrels to spread north.

“Greys have already displaced red squirrels from most of England, Wales and Scotland’s central belt, but much of the north still remains grey-free,” he said.

“With sightings of greys becoming more frequent in northern Perthshire and Angus, and a population of grey squirrels already established in Aberdeen, it is imperative that we act quickly to protect red squirrels north of the central belt and prevent the grey’s further migration.”

Stuart Brooks, from SWT, added: “I can understand and empathise with those people who do not like the prospect of killing wild animals, but it is disingenuous to say that there are viable alternative solutions to saving the red squirrel in Scotland.

“Work is under way on a vaccine for squirrel pox but it is not around the corner and habitat improvements are a key component of our longer-term strategy.

“To do nothing now will certainly consign our native squirrel to a painful and lingering death.”

The SSRS project is expected to start work properly in April.

Source: BBC News website

Date: 10/02/2009

World Conker Championship ‘in doubt’


Bleeding cankers and leaf miner moths are threatening this year’s World Conker Championship, say organisers.

The Daily Telegraph reports that the dual assault on the UK’s horse chestnut trees is leading to a shortage of conkers, which has left the competition’s officials fearing that the event may have to be cancelled for the first time in its history.

The paper says the Forestry Commission estimates that half of the UK’s horse chestnuts are showing symptons of bleeding cankers, while the leaf miner moth affects many southern specimens, primarily in the South-East.

Organisers say they are considering importing conkers from mainland Europe.

Source: Daily Telegraph, UK

Date: 08/08/2008

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