An outbreak of Ash Dieback Disease (Chalara fraxinea) has been confirmed in our area. Worse still, it’s in the Landmark MD’s garden in the Chew Valley south of Bristol. Nick noticed some possible early signs in late May and these became more marked in June. He submitted a report to Tree Alert via the Forestry Commission’s website (http://www.forestry.gov.uk/treealert?open&A=Y), with photos, a map reference and a detailed description. The Commission responded impressively promptly to request a site visit by one of their field scientists. He extracted a sample from high up in the crown – which entailed a very long-handled saw and much dexterity.
The sample comprised living and dead tissue from the extracted stem, along with green and black leaves. These were tightly sealed in a bag and clearly labelled before being sent to Alice Holt laboratories in Hampshire. The Forestry Commission officer then rigorous doused all tools and clothing before leaving the site.
This is unfortunately the first record of Chalera in the ten kilometre square, but perhaps not surprising given that areas to the south around Wells and Shepton Mallet are already infected. It is clear that biosecurity is more important than ever – we may be too late to save all of the nation’s ash trees in the long term, but it is nonetheless important to be aware of the risks of infection caused by, for example, not cleaning pruning tools properly.
So what should you to do with the infected tree? The Forestry Commission advises that unless it is a hazard, from falling branches, or if it becomes an eyesore, there is little merit in felling the tree.
The disease is now in the area and it spreads from airborne spores produced in damp foliage in the leaf-litter under trees, rather than the foliage in the crown, so cutting the tree down won’t help. Fortunately the area under Nick’s infected tree is not suitable for the fungus to thrive and produce spores, so keeping the tree, which marks an historic lane and supports a wide range of wildlife, shouldn’t exacerbate the problem. There is some good news – the adjacent ash trees show absolutely no signs of the disease but, not surprisingly Nick is keeping a very close eye on them. If you are interested in the spread there is an interactive map which shows the 10K squares containing infected trees at http://chalaramap.fera.defra.gov.uk/.