The virulent disease ash dieback has been found in three new species belonging to the same family, raising fears that other plants including some garden favourites might be next in line.
Staff at the Westonbirt Arboretum in Gloucestershire became suspicious when specimens of mock privet (Phillyrea latifolia), narrow-leaved mock privet (P. angustifolia) and white fringetree (Chionanthus virginicus) growing at the garden not far from ash trees infected with ash dieback began to exhibit the same symptoms.
Now the Forestry Commission has confirmed that they were indeed suffering from the same disease. All are in the same plant family, Oleaceae, which includes garden favourites like Osmanthus and lilac – although so far these have remained unaffected, and the Forestry Commission says it does not believe the discovery will have a ‘significant impact on the environment’.
Chalara ash dieback was first confirmed in the UK in 2012 and is caused by a fungus, Hymenoscyphus fraxineus. It causes leaf loss and crown dieback in affected trees, with the dead leaves characteristically held on the tree long afterwards. Once infected, the disease is usually fatal.
‘Landscapers, gardeners and tree practitioners should be vigilant for signs of ash dieback on these new host species and report suspicious findings,’ said the UK’s Chief Plant Health Officer, Professor Nicola Spence.
For the last five years the government has led the world’s largest research project into screening trees for potential resistance to ash dieback, with Forestry Research identifying over 30 ash species in arboreta like Westonbirt which will be used in the trials.
Scientists are also working to sequence the genome of ash dieback to better understand the biology of the disease. A ban on movement of ash trees has also been in place since 2012 to try to prevent the disease spreading. All new cases should be reported to the Forestry Commission at www.forestry.gov.uk/treealert.