24 May, 2017

Ash Tree Dieback Disease – countryside users urged to look out for diseased trees.

Local conservationists urge everyone to look-out for ash tree dieback disease, now confirmed in both the wider environment as well as in saplings in areas bordering Ryedale.

Among local areas which could be hard-hit is the Howardian Hills Area of Outstanding Natural Beauty where the ash and oak are the main native canopy tree species.  Broughton Parish has some of the first ash trees to be found on the eastern side of the AONB.

Updates on this disease, especially alarming for areas of Ancient Woodland on calcareous soils such as those typically fund in Ryedale, can be found on the Forestry Commission website.  As it is such a fast-moving situation, regular visits are recommended – especially as the site has an excellent map showing the locations of confirmed cases as well as advice on how to identify affected trees.  There is also a facility on this site to report any suspected sightings of diseased trees.

Selina Scott is among those  with reasons to fear ash tree dieback disease. Her concerns stem around newly planted woodland on her farm between Coxwold and Ampleworth. See her story here.

The common ash tree.

Typical ash tree in full leaf during the summer.

Common ash trees, Fraxinus excelsior, also known as the European ash, are the fourth commonest tree in Britain (Woodland Trust). It is a deciduous broadleaf, often dominant on heavy or calcareous (lime-rich) soils which are typically found in Ryedale, especially in parts of the Howardian Hills Area of Outstanding Natural Beauty.

The ash also survives on poor soils where few other trees can grow. It can live for some 400 years and has a high conservation value. British folklore credits the ash with a range of protective and healing properties as well as the ability to predict the summer weather according to when the buds open in Spring! The prediction is found in the well-known saying “Oak before ash, in for a splash : Ash before oak, in for a soak”.

Common ash trees do not just grow in woods – they are also commonly found in hedgerows.   Many can be found in Broughton Parish, including in the village, perhaps notably towards the top of Main Street (Moor Lane.).

Serious threat of wipe-out.

The ash is now under serious threat from a fungal disease which could wipe out nearly all the ash trees in the country. Ash dieback disease, Chalara fraxinea (C. fraxinea), is a windborne fungal disease. The disease causes leaf loss and crown dieback in affected trees, and usually kills the tree.  Any species of ash risks being attacked.

Rowan tree – similar leaves but no relation to the common ash tree.

Ash dieback does not affect mountain ash (Sorbus aucuparia), also known as the Rowan tree. (See picture on right.)  They are unrelated to the true ash trees such as the common ash which is of the genus Fraxinus in the olive (Oleaceae) family.

But there are some of this family which can be found in gardens and parkland – these include Fraxinus excelsior ‘Jaspidea’ which has yellow leaves in spring, and a golden colour in autumn, and the smaller weeping ash, Fraxinus excelsior ‘Pendula’.

Facts

The Forestry Commission advice says spores are short lived with high doses needed to infect trees. Infected trees show signs of disease within months and cannot be cured. Those trees which survive the disease are likely to have a genetic resistance. Infected dead leaves produce the spores from June to September inclusive. The FC states there is “a low probability of dispersal on clothing or animals and birds”.

You can help by reporting any diseased trees.

Local conservationists are concerned.

Local conservationists Don Davies (Countryside Officer with Ryedale District Council) and Paul Jackson (Manager of the Howardian Hills Area of Outstanding Natural Beauty Team) are deeply concerned.  They  urge people to keep a look out for the disease which needs to be reported to the Forestry Commission.

“Most of the local ancient woods in this area are mainly ash which is the predominant native tree in calcareous woodland.  The ash is important for invertebrates, many rare, as well as tree roosting bats,” said Don Davies.

“The Ryedale Bap (Bio-diversity Plan) states there are around 236 ha of ancient semi natural woodland in Ryedale the majority of which is ash woodland.” (Ryedale District Council website, Ryedale BAP Page 24 http://www.ryedale.gov.uk/pdf/RYEDALE_BAP.pdf)

Ash tree keys (seeds).

Don explains that ash is good at setting seed in existing woods, often forming dense stands of saplings in natural gaps in woodland canopy. Often a major constituent of a wood’s under-storey, it is late to come into leaf allowing lots of light onto the ground benefiting woodland wildflowers. An additional benefit is that ash leaves seem to break down quickly, so do not mulch the soil as other tree leaves can do.

His concerns are not just for the loss of magnificent ancient woodlands, but also how any large scale loss of ash trees could be replaced, pointing out practical benefits such as the use of ash in landscaping schemes to hide developments and its popularity as a fine firewood.

Paul Jackson points out that within AONB woodlands, ash and the oak are the two main native canopy tree species.

Ash tree leaf.

He says losing ash trees would have a “highly significant impact on woodland biodiversity” as the likely alternative, the sycamore, casts a significantly denser shade than ash which would “impact negatively on woodland ground flora.”

He recalls working in Essex after the devastation of Dutch Elm Disease. Knowing that English Elm suckers grew happily for about 20 years before they too succumbed to Dutch Elm Disease, he worries that the same might happen to the ash.

“If the same thing happens with ash in our best native woodlands, then the impacts on biodiversity are likely to be serious” said Paul. “Ash often produces thickets of young trees in Ancient Woodland, which is why it is of high biodiversity value. A species cannot survive long if it cannot produce offspring that survive to maturity.”

“We encourage anyone walking in the countryside to look out for potentially diseased trees and report them to the Forestry Commission. But in the winter the only symptoms visible will be the diamond-shaped grey/black lesions where branches join the stem. This can only really be seen in young trees, so trying to spot the disease in mature trees in winter is impossible.

“Although it would be good if people could let us know out of courtesy if they find a diseased tree, we don’t have the staff resources to collect and pass-on sightings.”

How to recognise ash die back disease and how to report diseased trees.

Details of ash die back disease together with a video showing you how to spot symptoms can be found on the Forestry Commission (England) website http://www.forestry.gov.uk/chalara.

There is also a pictorial guide which can be downloaded.

The disease is notifiable and anyone who suspects an ash has ash die back disease is legally required to tell the authorities.

Contact details, given on the Forestry Commission website are:

Chalara helpline: 08459 33 55 77 (open 8am – 6pm every day)  or plant.health@forestry.gsi.gov.uk

 Mobile phone users

Those with mobile phones can go to Ashtag.org – a website set up especially to monitor the spread of the disease and to make it easy for people to report any suspected sightings, including photos and a GPS location via their mobile phones.

Ash Tag is supported by both the Forestry Commission and the Woodlands Trust among others and provides a cross-link to the FC website.

(AGW Dec 2012)

 

 

 

 

 

 

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