a Science & Technology


A seven-acre section of woodland near Bickleigh belonging to farmer John Greenslade has been decimated by the disease, and a major programme to uproot and destroy affected trees is under way.

Mr Greenslade began planting Byway Woods 20 years ago and has won awards for it.

By far the most interesting part of the discussion, and perhaps the more optimistic, was identifying how we might rise to the challenge of making our precious trees and woods more resilient in the face of these on going and inevitable threats. With the input of renowned woodland ecologist, Keith Kirby from University of Oxford, the group considered how the natural and cultural history of our woods has shaped them – and what we can do to give nature a helping hand.

This cannot be a ‘one size fits all’ approach and there is no simple template that all woodland owners and managers should follow – in fact the tendency to try and manage all of our woods in the same way in the past or previous suddenly shifts in management resulting from pursuit of narrow theories has probably made them more vulnerable today. A vulnerability compounded by the continuing gradual loss of woodland and the fragmentation of woods and other habitats, leaving them disconnected and isolated.

But some key principles are emerging. Our woods will be more resilient if they contain a wider range of native species, and have a more diverse structure too – so that we have a good mix of types of trees and a range of young, established and older trees.

Prof Erik Kjaer from the University of Copenhagen, confirmed that a small proportion (around 2%) of ash may be naturally resistant or tolerant to chalara. There are also good signs that this characteristic can be passed on to progeny of those surviving trees.

http://wtcampaigns.wordpress.com/2013/06/28/making-our-woods-more-resilient-tapping-in-to-the-insight-of-experts/

See what we are doing: The Natural Ash Nursery –

http://worldwidewood.wordpress.com/2013/06/17/natural-ash-nursery-cleared-and-ready-for-the-deer-fence/

Thousands of mature, native ash trees are being dug up and burned after the devastating disease ash dieback was confirmed in Devon.

About 2,000 trees at Byway Farm near Tiverton are affected, according to the Forestry Commission.

This is the first confirmed case of the disease in mature, native trees in the region – another nine cases have been confirmed in young trees that have been recently planted at sites across Devon and Cornwall, including two sites on Dartmoor National Park, according to Forestry Commission figures.

Ben Jones, of the commission’s England plant protection team, said: “It appears that the affected trees had the disease when they were planted in 1996-97. It is concerning and we are continuing our investigations into how the spread had taken place and how far it has spread.”

http://www.westernmorningnews.co.uk/Trees-burned-infection-ash-dieback/story-19481835-detail/story.html

The genetic insights could eventually be used to cross Tree 35 with breeding stock from our native ash population. Tree 35 is predominantly female and the genetic make-up could help identify a predominantly male UK tree with resistance to make a breeding pair. Or it could be used to identify both female and male UK trees with similarly low susceptibility to the fungus. A combination of crosses might be needed for a lasting comeback from the epidemic.

Ash trees are almost always fertilised by pollen from another ash tree rather than by self-pollination. This generates two copies of each chromosome in the resulting seeds. Although very similar, the chromosomes tend to have many differences when you look at the detail. This ‘heterozygosity’ makes it difficult to generate a genome sequence because in effect you have to put two genomes together at the same time.

Tree 35 has been identified as highly heterozygous.

http://www.tgac.ac.uk/home/news/54/68/Genome-sequence-for-mother-of-ash-dieback-survival/

The scientists are extremely hopeful that, having determined the tree’s complete set of genetic material – through a process known as genome sequencing – they have paved the way to identify those genes which might be connected to its ability to withstand the fungus.

Although the breakthroughs have raised hopes that a new breed of ash will be able to grow and survive in the face of the fungus, they will do nothing to protect Britain’s 80m existing ash trees, which are all under threat.

Adult clones of tree 35 grown from cuttings taken from the original trees in the 1930s were recently discovered on the Danish island of Sealand. [However] just planting this variety of Ash in the UK would result in a narrow genetic base making the species vulnerable to future diseases, experts said, adding that the latest breakthroughs still represented a giant step forward for the long-term prospects of the tree in this country.

http://www.independent.co.uk/news/uk/home-news/genetic-secrets-of-resistant-tree-gives-new-hope-over-ash-dieback-disease-8660992.html

Scientists have sequenced the genome of a type of ash tree with resistance to the deadly fungal disease sweeping the UK.

The development could be the starting point for breeding a strain of ash to replace thousands expected to succumb to ash die-back in the next few years.

All the data is being put on a crowd sourcing website OpenAshDieBack to enable experts from around the world to help identify genes that might be connected to the trees’ ability to withstand the fungus.

These genes could then be part of a breeding programme for resistant trees.

The samples for the latest research came from so-called “tree 35”, a strain of ash from Denmark originally bred nearly 100 years ago, which has shown an ability to tolerate the fungal disease, when virtually all its Danish relatives were wiped out.

Prof Allan Downie of the John Innes Centre believes this genetic understanding of both the lethal fungal infection and the surviving strain could help fill the impending gap in the canopy.

“We’re trying to give nature a bit of a helping hand by identifying the right kind of (native) trees to do the appropriate crosses,” he said.

http://www.bbc.co.uk/news/science-environment-22913111

The Genome Analysis Centre (TGAC) has worked fast to sequence and assemble the valuable genome of the survivor “tree 35” from the recent Ash Dieback outbreak that have caused devastating damage to the Danish Ash woodlands and that now threatens the UK trees.

This information will be useful to those that are trying to find the trees that would offer at least a partial resistance and can be used to replace the now empty woodlands and remediate the damage.

This work contributes to the Nornex consortium, part of the Biotechnology and Biological Sciences Research Council (BBSRC) and Defra funded bioscience response to ash dieback (Chalara fraxinea). Prof. Erik Dahl Kjær and his group have been instrumental in the success of this project, read more about his work on this here.

“The genome sequence of this ash will be an essential tool that can help us to follow the inheritance of the ability of some ash trees to tolerate and to inhibit the growth of the Chalara fraxinea pathogen. Such knowledge will help generate new varieties of ash trees that can withstand attack by the fungus,” said Prof. Allan Downie at the John Innes Centre.

http://www.tgac.ac.uk/news/52/68/Unravelling-the-genetic-code-of-the-Ash-Dieback-survivor-tree-35/

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