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Ash dieback

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What is ash dieback?

Ash dieback is a serious disease of ash trees caused by a fungus called Hymenoscyphus (formerly Chalara) fraxineus. Trees affected by the disease suffer leaf loss and crown dieback, and they usually die. It is unlikely that any 'cure' or prevention measures will be available in the forseeable future.

Ash trees suffering ash Dieback have been found across Europe and the disease is now becoming widespread in the UK.

The disease tends to kill saplings and young trees fairly rapidly, but it may take 20-30 years for mature trees to succumb. They may even appear to recover from the disease, but in the longer term are likely to die.

Ash trees in the Peak District

Ash trees are the most common tree in the central limestone area of the Peak District National Park (known as the White Peak). There are an estimated 8 to 9 million ash trees of various ages, and ash is the overwhelmingly dominant tree in the woodlands of the steep limestone dales, where it may comprise up to 99% of the tree cover.

These limestone dales contain the largest areas of ravine woodlands in Great Britain and are the best examples of this habitat in the UK. The White Peak is one of the most important areas in Europe for ash-dominated landscapes and habitats. The Peak District supports 21% of the UK’s ravine woodland. This mosaic of woodland, scrub and grassland habitats support rich invertebrate and plant communities, such as lily-of-the-valley.

They are of international significance: the Peak District Dales Special Area of Conservation covers seven dales and contains almost 900 hectares of ravine woodland, including the iconic landscapes of Dovedale, Monsal Dale, the Hamps and Manifold Valleys and Lathkill Dale.

Ash trees are also a major feature of the Peak District's landscape, particularly across large parts of the White Peak plateau as field boundary trees, village trees and important components of the small copses that are so characteristic of the White Peak.

Ash dieback in the Peak District

Ash dieback was first found in Britain in 2012 and was predicted to reach the Peak District within about 3 years. As expected it was confirmed in the Peak District in July 2015. It is expected to spread quickly throughout most of the Peak District, particularly the White Peak, over the next year or two.

Because it affects young trees most severely it is likely that the majority of young Ash trees in the Peak District will become infected and die over the next few years. However because mature trees often take some years before the disease causes death it is unlikely that we will see a lot of large ash trees dying for several years. The longer-term consequences in the Peak District are likely to be:

  • loss of 60-90% of Ash trees, with significant long-term impact on the landscapes of the White Peak plateau and dales
  • probable replacement of ash woodland by scrub and sycamore (non-native) in the limestone dales woodlands
  • an associated loss of biodiversity
  • financial impact through loss of ash as a timber crop
  • cost of managing dying trees and encouraging replacement trees.

Experience from continental Europe suggests that the disease cannot be stopped, and it is likely that between 60% and 90% of the UK’s estimated 80 million ash trees will die over the next 20-30 years. To put this into context, Dutch Elm disease killed around 25 million trees in Britain.

Managing ash dieback nationally

The UK government accepts that it will not be possible to eradicate the disease. The national strategy is to research disease-tolerant strains of ash and to consider alternative replacement species where necessary.

The Peak District National Park Authority endorses the national action plan, and particularly the recognition that our existing trees are a vital resource from which to identify tolerant strains of ash. In the longer term, the aim is to identify and encourage tolerant strains of ash.

What are we doing about ash dieback?

In line with the national action plan and in anticipation of ash dieback reaching the Peak District, the Authority has been working with partners to:

  • help monitor for the presence of ash dieback
  • raise awareness among tree contractors, nurseries, parish councils and the public
  • highlight the importance of the Peak District’s ash woodlands
  • establish long-term monitoring plots in the dales woodlands to assess the impacts of the disease
  • plant thousands of new trees through a partnership with the Woodland Trust
  • develop options for future long-term tree and woodland management.

Frequently asked questions

1. Should I avoid visiting the Peak District because of ash dieback?

No, please continue to visit the Peak District. It is unlikely that visitors play a significant role in the spread of the disease, which is predominantly wind-borne.

2. Do I need to clean my footwear?

Yes. We are following current national guidance in asking people to clean obvious mud and leaves from footwear, pushchairs, bikes, cars, dogs and horses if you have been walking/riding through any of the ash woodlands in the limestone dales. We also ask people not to remove leaves, plants or wood from woodlands. Whilst it is unlikely that small amounts of material will spread the disease, it is a reasonable precaution to remove more obvious material.

3. What if I suspect an ash tree has the disease?

If you think you have spotted the disease, please check the symptoms video and guide on www.forestry.gov.uk/chalara and, if you still think it is ash dieback, provide your details on the tree alert form.

4. Is the disease dangerous to other species or animals?

The disease poses no risk to human or animal health, and is not known to affect other tree species. National guidance states that the risk of spreading the disease by humans or animals is low. However, we are asking people to reduce the risk of spreading the disease by cleaning outdoor equipment (please see question 2).

5. Can I plant a new ash tree?

At present no strains of Ash are available which are known to be tolerant to ash dieback. It is therefore highly likely that any newly planted ash would become infected and die. In addition restrictions on the movement of ash plants, trees and seeds, introduced when the disease was first discovered in Britain in 2012, still apply. In most cases it will  therefore be more appropriate to consider suitable alternative species.

6. Should infected ash trees be removed?

If young ash trees planted since about 2007 are found to be infected then they may have been infected at the time of planting. It may therefore be appropriate to remove them to help slow the spread of the disease. The removal of other infected trees is not recommended as it is unlikely to significantly slow the spread of the disease. Furthermore, it may result in the loss of trees which might have proven more tolerant of the disease, and it will be important to retain such trees to provide a seed source for the future.

7. What should I do if I own or manage an area with ash trees?

In general it will be important to retain existing Ash trees so that more tolerant individuals can be identified to provide stock for the future. Ash dieback affects young trees and new regrowth most severely. It is therefore likely to be some years before it causes structural problems in mature ash trees:

  • retain ash trees where possible
  • check for signs of ash dieback regularly and report any suspected cases via the Forestry Commission’s website (see question 3 above)
  • minimize any pruning or tree surgery, as young regrowth is more susceptible to the disease
  • keep an eye on the tree’s safety as the disease progresses; pre-emptive action is generally not recommended as some trees may prove more tolerant, and unnecessary work on the tree may make it more susceptible
  • consider planting other species appropriate to the location.

8. Where can I found out more about ash dieback?

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