ASH DIE BACK (CHALARA FRAXINEA)

You may be interested in the information below. I was asked recently for the Council view on this issue. I took this up with Forestry and set out below is the response I received.

Summary of main issues

  1.  The ash tree (fraxinus spp.) population throughout the UK (approximately 5% of woodland cover) is threatened by the fungal pathogen, Chalara fraxinea, which causes dieback in ash trees.
  2. C. fraxinea was confirmed as being present in the UK in March 2012 and is being treated as a quarantine pest under national emergency measures.  It is important that suspected cases of the disease are reported: national contact details given at foot of attached Forestry Commission Pest Alert leaflet (see paragraph 7 below).
  3. Scores of newly planted sites throughout the UK are being monitored, many have confirmed infections, including one near north Leeds.
  4. The UK Government banned the importation of ash trees on 29th October 2012.
  5. The disease has, however, been confirmed in the wild population on a number of sites in East Anglia.
  6. Last week the UK Government convened a meeting of COBR to co-ordinate work across all main Government departments and their agencies with a view to controlling the disease.
  7.  Up to date information can be obtained from the Forestry Commission’s website: www.forestry.gov.uk/chalara

 1                           Purpose of this report

1.1                     To brief Members and senior Council officers about the severity of this tree pathogen and the potential consequences for Leeds.

 2                           Background information

2.1                     Originating in the far east, where it exists harmlessly amongst the oriental ash population, the C. fraxinea was identified in eastern Europe during the early 1990’s and spread rapidly through central and western Europe. It is an aggressive fungal pathogen, with the potential to kill 90% of European native ash populations – as highlighted by the devastating effect it has had on the Danish ash population.

2.2                     C. fraxinea was first discovered in the UK in March 2012 in a consignment of young trees imported from the Netherlands to a Buckinghamshire nursery. Since then it has been discovered on a variety of sites throughout England, plus a site west of Glasgow, all planted with imported nursery stock during the past 5 years.

2.3                     A newly planted privately owned site in north Leeds is thought to be infected (no details as yet).

2.4                     In late October 2012, C. Fraxinea was found in the wild ash population in East Anglia. It is thought that this infection may be the result of wind blown spores from the continent. This suggests that the fungus may have been present in the UK for a number of years.

2.5                     As well as affecting young, recently planted trees originating from imported nursery stocks, in nurseries, C. Fraxinea  poses a clear risk to our native forest trees, plus trees in urban settings, such as in parks and gardens and along road verges.

2.6                     Forestry Commission staff and officers from the Food and Environment Research Agency (FERA) are focused upon assessing the spread of the disease in the UK, both in recently planted sites and, crucially, the extent of infection within the wild population in East Anglia.

2.7                     Where C. fraxinea is confirmed, the Forestry Commission uses its statutory powers to order land owners to up root or fell infected trees and destroy them on site. No movement of ash trees away from infected sites is allowed. The sanitation of infected sites must be undertaken within a strict timeframe and at a landowners own expense.

3                           Main issues

3.1                     Public concern – it is anticipated that P&C will receive a high number of enquiries. All P&C staff are being briefed on the symptoms to look for. The Forestry Section, will co-ordinate referrals to he Forestry Commission.

3.2                     Symptoms are described in the attached Forestry Commission pest alert leaflet (paragraph 7 in above summary).

3.3                     Potential Loss of 90% of the UK ash population. In Leeds this represents a considerable proportion of our native woodland cover (as much as 1/3 in some areas).

3.4                     Identification of the disease in the wild, significantly increases the chances of it reaching Leeds. The timescales are uncertain.

3.5                     Identification of the disease in LCC owned young plantations (potentially those planted within the past 5 years) will mean that we have to destroy all the ash trees present. This will include plantations at Temple Newsam, East Ardsley, Leeds New Forest Village and Water Haigh Park (Woodlesford).

3.6                     P&C are actively monitoring our young plantations and keeping in close contact with the Forestry Commission.

3.7                     Identification of the disease within our native ash population (all age groups) may lead to an instruction for us to fell and burn on site all infected trees. However, it may be too late at this stage for such action to have any positive effects on the ash population at large. Nonetheless, there will be a need to assess the potential risk that dead trees present to people and property and to implement the necessary mitigation.

3.8                     Potential capital cost of sanitation felling are likely to be significant. A figure of £1000 per mature tree (to dismantle/fell and burn on site) would not be an unreasonable estimate.

3.9                     Currently, LCC’s tree management budgets focus on the management of identified risks. The potential for a rapid increase in dead trees in high usage areas (bordering highways and residential areas for example), may create a substantial pressure on existing budgets.

3.10                  P&C have placed a carpet ban on planting of any ash trees until further notice.