I visited the Forestry Commission website which lists the whole range of current tree pests and diseases.
The most topical of interest to foresters and landowners at the moment being Acute Oak Decline – a condition affecting oak trees in parts of England and Wales; Chestnut Blight, a highly damaging disease caused by the fungus cryphonectria parasitica, which has been confirmed in sweet chestnut trees and, of course, Chalara dieback of ash – an aggressive fungal disease of ash trees which causes crown death and wilting and dieback of branches.
Other diseases affecting commercial conifer species include; Dothistroma needle blight – formerly known as red band needle blight, and caused by the Dothistroma Septosporum fungus, which causes mortality and loss of timber yield in pine trees and Phytophthora Ramorum, a fungus-like organism which attacks many trees and plants – the most economically important of which is larch, and large numbers have had to be felled both in the west country and in Wales.
However, there was one non-native pest that was ominously omitted from this page of the website – grey squirrels.
Unlike imported ash trees, grey squirrels have not been subjected to government regulation or control but cause a significant amount of damage to the nation's trees.
The grey squirrel is among the top 20 non-native species inflicting the highest annual direct costs to the British economy – estimated at £14 million per annum.
Invasive Non-Native Species, according to a report from an international research organisation are costing the UK economy at least £1.7 billion per annum.
Grey squirrels cause irreparable damage by bark-stripping the tree of both coniferous and broadleaved species, most commonly of young plantations under 40 years old, including beech, oak, wild service tree, field maple, sycamore and Norway spruce.
There is also evidence that they are contributing to reducing bird populations by stealing birds' eggs, killing off our native red squirrel largely because greys are 'carriers' of the squirrel pox virus which is fatal to the red squirrel.
As foresters look around, against all the odds, to plant alternatives to ash (not the grey's preferred browse) and to restructure and restore Plantations on Ancient Woodland
Sites with site native broadleaves, many of which are favoured by grey squirrels, grey squirrel control has to be one of the Environment Minister's most critical and pressing issues he needs to address if quality timber is to be produced in the future and that Forestry Commission grants for new planting (£32.2 million out of a total of £51.4 million in forestry grants) is seen as taxpayer money well spent.
A case study of an oak plantation published in April 2012 by Forest Research showed that 61 per cent of all the trees had some damage and between two and 17 per cent would be ring-barked above 4 million in any year.
I have witnessed such damage myself on properties I manage.
Martin B. Jones is a forest management consultant and Managing Director of "The Woodland Stewardship Company" based in Shrewsbury