Chalara dieback of ash – (Chalara fraxinea)

Tree health has been a hot topic in recent weeks following the introduction of a new tree disease into the UK. There has been much press coverage regarding the potentially serious threat to one of our most valuable native trees – Ash.

Chalara dieback of ash is a serious disease of ash trees caused by a fungus called Chalara Fraxinea. The disease causes leaf loss and crown dieback in affected trees, and usually leads to tree death.

The disease appears to have been introduced on imported nursery stock and is now being treated as a quarantine pest under national emergency measures. However, now that the disease has been found in older trees (East Anglia, Kent and Essex) with no apparent connection with plants supplied by nurseries, government scientists are investigating the possibility that it might have entered the UK by natural means; such as wind borne spores or birds coming across the North Sea.

It is still very early to judge what the position is and the Forestry Commission and DEFRA are still gathering information so the full impact that the disease will have in England is not yet known.

If we look to the other countries that have suffered with the disease it looks very likely that 60-90% of UK ash trees will be infected in the foreseeable future. Ash trees make up 5% of the UK tree population so this will have a significant impact on our towns and countryside.

The disease is a fungus that readily infects young trees and saplings but affects older trees more slowly. The main spread of the disease is through the movement of young plants and this is now being controlled. The majority of the reported outbreaks relate to young planting with a few cases of mature trees being affected.

The disease spreads slowly on its own (12-20 miles per year) and mainly through spores on leaf litter and twigs from June to September. This means that we will get a much better idea of the extent of the spread by the end of next summer. Our current knowledge of the spread is based on sample plots inspected by DEFRA.

There are no reasonable controls (at the moment) and it looks very likely that the policy will be to allow the disease to run its course rather than undertake sanitation felling. The problem with sanitation felling (removing all the trees in an area around an outbreak) is that it is expensive for landowners and you lose trees that may be resistant to the disease. So in the long term it is better to identify the resistant trees so that we can re-establish the ash tree population.

The current advice is that mature trees may live for some time after infection so felling trees hastily may be too harsh a measure when some benefit can still be gained from keeping the tree.

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Aspect Tree Consultancy launches with training seminar

Welcome to the first blog posting by Aspect Tree Consultancy Ltd.

The company launched in November 2008 and combines the talents and experience of Dominic Scanlon, Jon Kiely and Chris Widdicombe.

On 4th February 2009 we ran our first seminar – Tree Risk Management for Housing Associations. The company has a policy of providing training and advice that will provide a public benefit across the South-West of England and beyond. The seminar was run in conjunction with Tor Homes, South Hams District Council and QTRA Ltd. A major part of the Aspect ethos is to work in partnership with other organisations and companies to make a real impact on tree care.

The event was a real success with excellent feed back from the delegates. There is no doubt in our minds that we got a great response because we made every attempt to make the day relevant to peoples actual jobs.

Many Housing Associations originated from Local Authorities but when they split they lost all the specialists that Councils have the benefit of. As a result many people responsible for trees have no training or experience in managing tree populations or managing the risk that they can pose.

Our event aimed to give the delegates an overview of tree management and how they can achieve sensible and affordable tree management – to suit their budgets. Trees generally pose a low risk of harm and managing the risk they pose should be guided by the location they are in and how frequently this is used.

The event started with Dominic providing an over view of tree biology and how poor pruning can increase management costs over the long-term.  This was followed by Simon Putt from South Hams District  Council giving advice on tree protections and tree work application procedures.

Quantified Tree Risk Assessment – an affordable system:

We promote the Quantified Tree Risk Assessment system and we had the honour of the systems author, Mike Ellison, giving a talk about QTRA. This was followed by a presentation by Rob Scholefield of Tor Homes who gave a working example of how he uses the QTRA system and how he has implemented a tree policy to ensure that he is spending his money where it is really required.

The benefit of this system is that is allows tree owners to identify the sites or areas that are most frequently used and then to focus their tree inspections to the areas of the highest use. By prioritising in this way tree owners can prevent expenditure on unnecessary inspections or overly detailed ones. There is also a reduced tree surgery cost compared to the works thrown up by the traditional survey method.

QTRA and Health & Safety Executive Guidance:

The QTRA system corresponds to the current HSE guidance and promotes sensible and simple methods for inspecting and managing trees.

Upcoming Aspect Seminars:

Aspect will be running another seminar to deal with Planning Applications and 1APP – to highlight what information applicants need to include with a planning application and why.  The seminar will deal with best practice and advice on how to minimise problems at the application stage.  If you would like to attendend this then please contact us to register your interest.