My blue cedar tree, which is about 15 years old, has been displaying a blighting appearance for the past few years, with pines readily falling to ground, though with some small clusters of fresh growth interspersed. The top metre or so of the tree appears quite healthy. Any hope that it can be rescued? P Maher, Co Wexford
I’m very sorry to say that your tree seems like it’s almost certainly suffering from a fungal disease known as Sirococcus blight, which originated in North America. In the last decade it has been identified in Britain and Ireland as well as parts of mainland Europe. Species of cedar and hemlock (Tsuga) are particularly vulnerable, including Atlas cedar (Cedrus atlantica), Himalayan cedar (C deodara), cedar of Lebanon (C libani), Cyprus cedar (C brevifolia), western hemlock (Tsuga heterophylla), mountain hemlock (T mertensiana) and eastern hemlock (T canadensis).
Tell-tale signs of infection including pink discolouration of the tree’s needles as seen in your photo, shedding of needles, wilting and dieback of young shoots, and the excretion of a sticky resin from dark red lesions/wounds on the bark. If you look closely, you may also spot small, dark fungal fruiting bodies on the branches that look a little like black moles or freckles. These symptoms are most obvious in spring-summer, when the disease is most active, which is also the time of year when healthy trees are most at risk of infection. The disease can also be spread via infected dead wood, needles and plant litter. The fungal spores are easily carried in wet, windy weather. There are no effective ways to treat it. Some affected trees can soldier on for years before eventually dying but will look increasingly unsightly and unhappy.
As awful as it sounds, my advice is to cut your losses and carefully dispose of your sickly tree rather than watch its slow but steady decline, making sure to burn the wood and collect, bag and burn or safely dispose of any needles. This would also be the best approach for phytosanitary reasons, greatly reducing the chance of it infecting any other vulnerable species growing nearby, either within your own garden and those of any neighbouring properties. Very sadly, the rise and spread of a wide variety of destructive tree pests and diseases in recent decades as a combined result of climate change and inadequate phytosanitary controls within the EU poses formidable challenges to our gardens and parks as well as the wild landscape. eppo.int
