Why you should plant a tree this autumn
It won’t have escaped you that many of our trees are suffering from climate change and the direct impact of population growth. HS2, the current Government’s flagship capital investment project is currently cutting a swathe through ancient woodland, removing centuries old iconic and ordinary trees alike.
Possibly one of the greatest impacts that humankind is having is on the loss of biodiversity. A simple example of this is that on one hand we are losing colonies of bees and populations of birds whilst on the other we are also experiencing new diseases and pests that survive due to climate change. In the UK today, pests and diseases arrive on high-sided trucks or on a consignment of timber which is how Dutch Elm disease originally came into the UK from Canada. So here are some key issues for trees that you may have and what you can do about it.
Lets start with Ash because we’ve all heard about the problem. Chalara fraxinea is being treated as a quarantine pest under UK national emergency measures; it is important to report any suspected cases. The disease caused by the fungus results in leaf loss and crown dieback in ash trees, which can lead to tree death in affected trees. Symptoms can be visible on leaves, shoots and branches of affected trees. Leaves can suffer from wilting and a black-brownish discolouration can occur at the leaf base and midrib. Dieback of shoots and twigs is also very characteristic. If you are in any doubt about ash trees in your garden then call an expert such as our own tree specialist www.thetreecompany.co.uk
Horse chestnuts are threatened by a leaf mining moth (Cameraria ohridella) which is believed to have come from the Caucasus, turning leaves brown and gradually weakening the trees. It arrived from France and was first found in a few trees on Wimbledon Common it has now spread across the south of England and the Midlands. You cannot treat the tree and it unlikely that you will be given permission to remove it but some years can be worse than others and indeed in 2020 the problem didn’t appear locally as bad as other years. But these trees are also under attack from a bleeding canker bacterial infection (Pseudomonas syringae pv aesculi) that is believed to have originated in the Himalayas and more seriously can kill the tree.
Alders, Larch and Oaks
Phytophthora Alni is now killing alders in large numbers and is believed to have hybridized in a nursery in Europe. Plantations of larch in South West England, Wales and Northern Ireland are being rapidly infected by another related and recently arrived species, Phytophthora ramorum. Over half a million larch trees have had to be felled last year in emergency sanitation measures.
The disease is typified by lesions on the trunk of the tree and rapid die back. Phytophthora ramorum also affects other trees, spreading from larch to beech and it’s seen in oak as ‘sudden oak death’. Whilst Phytophthora ramorum has been more of a threat to the American red oak in the UK than to our native oak trees we must expect that our iconic English oak will come under threat at some time in the future. And of course the Oak Processionary Moth is now found in oak trees across the main boroughs that we work in including gardens in Wimbledon, Richmond and Putney.
It’s not all doom and gloom though and after the Government’s consistently poor management of tree policies over the past few years we seem to be moving to a moment where there is now investment in research to find solutions, not just government but also privately funded. There are some new tree planting programmes including re-planting new disease-resistant forms of Elm across London. But remember if in any doubt some of these diseases are now reportable so keep an eye on your trees, find out more at great websites such as rhs.org.uk, get advice from the local authority registered companies and call an expert in if you are in any doubt