Defra advises on ash tree dieback

By Amy North

Local authorities should prioritise incineration and landfilling of green waste suspected to be infected with Chalara, instead of sending it for composting, according to an advice note issued by Defra.

Residents are being encouraged to deal with infected leaves by burning them or composting them within their land and if this is not possible placing them in their residual waste bin for disposal. Despite this, councils said there were no concerns that this would have an effect on recycling rates.

Withering of young leaves caused by Chalara fraxinea fungus. Photo courtesy of Forestry Commission
Withering of young leaves caused by Chalara fraxinea fungus. Photo courtesy of Forestry Commission

The advice note was issued by the Department for Environment, Food and Rural Affairs yesterday (November 28) following a recent outbreak of Chalara dieback in ash trees across the UK.

Chalara fraxinea is a fungus which causes leaf loss and crown dieback in infected trees which usually leads to the death of the tree. The infection is spread via spores from fruit bodies on leaf litter. Cases have been confirmed in a number of counties including: Berkshire; Essex; Kent; Lincolnshire; and Yorkshire.

The guidance aimed at householders, landowners and councils aims to address the options for the disposal of ash tree leaves and saplings infected by Chalara in a bid to prevent or slow down the spread of the disease. The advice follows consultation with, among others, the Environment Agency, the Food and Environment Research Agency and the Forestry Commission.

Arrangements

Defra said it seeks to accommodate existing waste management practices as far as possible and minimising disruption to local authority operations in particular. Where there is no suspicion that trees and leaves are infected with Chalara the leaves can be left where they fall and councils can continue with existing arrangements.

It states: Local authorities should advise householders not to put out green waste suspected of being affected by Chalara, but to deal with it within the curtilage of their own premises, wherever possible. Where it is suspected collected green waste is affected, local authorities may choose to continue sending this for composting nearby, although this is a less preferred option if the compost is known to be intended for use at distant locations.

Local authorities are encouraged to discuss this with their contractors. Local authorities should prioritise incineration with energy recovery or landfill at an existing permitted site, where these are available nearby.

Treatment

The preferred way to manage any infected vegetation, depending on its nature and location, in decreasing order or preference is:

  • Burning in situ on the ground or in mobile incinerators brought to site (where these are used because they offer a practical solution to deal with a high volume of leaves);
  • Burial in ground (option for householders only);
  • Composting in situ;
  • Incineration or landfill off site; and;
  • Composting and other biological treatment off site.

Defra said there is no clear scientific evidence available on the effect of composting on Chalara spores meaning composting is the least desirable method for dealing with the waste. The Department said: The temperature increase during the composting (including AD and treatments at MBT) process and the presence of decomposition fungi, which will decompose leaf material rendering it unsuitable to sustain Chalara may lead to its destruction.

However, it added that given the uncertainty around the destruction of Chalara in the composting process, it is advised that wherever possible the resulting compost should be spread on or near the infected source and not passed on to a third party where it may be transported considerable distances. In addition, any leaves that are not destroyed or processed should not be used for mulching or use on allotments where the infection may spread.

Defra said it is working to gain a better understanding of the disease and its thermal death point.

Recycling

Instead local authorities are being urged to encourage householders (where possible) to compost or burn the leaves on their own land and if not place them in residual waste bins for collection.

Speaking to letsrecycle.com Andrew Bird, West Midlands representative and organics expert for the Local Authority Recycling Advisory Committee (LARAC) welcomed the guidance and said he was unconcerned about the effect the proposed treatment of the material would have on recycling rates.

He said: I have not heard any concerns about the effect it will have on recycling rates at this stage. I have certainly not had any feedback.

Mr Bird added that LARAC is awaiting a further action plan from the government and will issue specific guidance for local authorities and householders within the next few months.

Defra has already taken action to minimise the spread of infection by implementing an action plan which includes the destruction of newly planted diseased trees and a ban on imports of ash trees as well as movement restrictions within the UK.

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