Millions of trees face the axe as ash dieback decimates landscapes across the UK – while measures are being stepped up to prevent a deadly new tree killer from getting a foothold the country.
The National Trust described this year’s record warm, dry spring, which placed trees under enormous stress, combined with the devastating effect of ash dieback, as a “perfect storm”. The charity, which needs to save £100million a year due to the Covid-19 pandemic, expects to fell at least 40,000 trees on its estates this year, at a cost of more than £2million.
Ash is currently one of the most common trees in the UK
It predicts that 75 to 95 per cent of all ash trees will be lost in the next 20 to 30 years, with around 2.5 million trees on National Trust land facing the chop. The Trust claims that frail, infected trees pose a risk to public safety. In the Cotswolds, a badly hit region, more than 7,000 trees are likely to be felled over the next year, with the Trust warning that the loss of native ash is a “catastrophe for nature” that will have a “devastating impact on wildlife and biodiversity”.
Asked what will replace felled ash, a spokesman for the charity, which earlier this year announced plans to plant 20 million trees, said: “This will be done at a local level with regional considerations in mind. Ash dieback provides an opportunity to establish a wider range of native species such as limes, field maple and alder as well as habitat-rich scrub species, and to consider the use of non-native species where appropriate.”
Alder could replace some felled ash trees
Royal Horticultural Society gardens have been affected by ash dieback, too. Although the disease is present at Wisley and Hyde Hall, no trees have been removed so far, but Harlow Carr is in a badly affected area which led to the loss of six large ash trees. RHS Rosemoor and Bridgewater have had to remove, or plan to remove, trees within areas of their woodland.
Dr Lisa Ward, Senior Scientist – Biosecurity at the RHS, told Candide: “Species diversification is an important element of future planting plans at all RHS gardens and has been core to our work for some time. For example, 10 years ago, RHS Rosemoor was badly affected by sudden oak death, requiring the removal of 15 acres of larch (also susceptible to sudden oak death), and the team is working with the Forestry Commission to re-plant native broadleaf species in their place. Harlow Carr’s annual tree planting programme sees the team plant around 100 new trees each year.”
Sudden oak death has been most destructive on oak populations in America
Curator at RHS Hyde Hall, Robert Brett, pointed out: “We are planning to plant more trees around Hyde Hall, including 200 for 2021. We have bought the elm Ulmus x ‘Wingham’, which is apparently resistant to Dutch Elm Disease, as an educational, interpretative piece for the garden. Maybe in a few years’ time, clones of Fraxinus with resistance to ash dieback will be available in a similar way.”
The RHS has also identified nine hosts of Xylella fastidiosa, a bacteria can infect more than 560 plant species. The disease has struck on mainland Europe but is not yet evident in the UK. Hosts including olive and prunus (such as cherry and plum) “present the highest risk of introducing the bacterium to the UK,” according to the RHS.
Imported olive trees could introduce Xylella fastidiosa into the UK
The Department for Environment, Food & Rural Affairs (DEFRA) is concerned about the threat posed by Xylella.
Chief plant health officer, Professor Nicola Spence, said: “We take the nation’s biosecurity seriously and currently have some of the strongest measures in Europe. The threat posed by Xylella has not changed. We will continue to thoroughly inspect plants which are imported to the UK.”
In April, DEFRA introduced new national “stringent” import requirements. Imported plants, which previously had to carry a declaration that they met DEFRA requirements, must now be accompanied by a Plant Passport, indicating they “meet the plant health standards of Great Britain”. Inspections of plants imported to the UK are being stepped up, while gardeners travelling abroad are being urged not to bring plants back from overseas.
Gardeners are being asked to remain vigilant and report any unusual symptoms on trees or plants at this website.