Bunny Guinness: The ash crisis shows it's time to rethink Britain's quarantine controls Sad is not the word to describe Robert Crowder, owner and chairman of Crowders Nurseries (crowders.co.uk) in Horncastle. Angry is probably more fitting. He notified the Forestry Commission in June that he had some ash trees showing signs of Chalara fraxinea. Then, he alleges, a movement order was issued forbidding him to cut, prune, destroy or treat the plants in any way. For three months, plant health inspectors visited, often more than weekly, going from the infected group of trees to other areas of their nursery which had clean ash trees. Defra claims necessary bio-security measures had been taken during the inspections to stop transferring the disease from one area to the other, and that Crowders could have taken the decision to destroy that stock itself. In September the nursery was ordered to destroy all its ash trees, even those in isolated areas where no disease was present. There is concern, too, about the provenance of the seed. Some people, such as Robert, believe in using locally sourced seed, as trees from their area will be more genetically adapted to growing in our climate. But it is a controversial area. Derek Patch, renowned arboriculturist from the Tree Advice Trust (treehelp.info), thinks that because of issues such as climate change, the key is to achieve genetic and species diversity, and to tighten up the screening of imported plants. Derek points out that when containers stuffed full of plants arrive at the docks it is difficult to check them all properly. But when I am working in places such as Japan, anything I import from Europe is vigorously screened. All plants have to be totally free of compost, with their roots well washed, before they are allowed in. They often spend days being checked at Sapporo after a long trip. Conversely, unloading a Dutch container lorry stashed with plants in compost, takes mere hours and the checks are probably cursory. Much of our nursery stock comes from Europe. It is competitively priced and well marketed. But if we enforced plant health regulations like they do in New Zealand and Japan, we would give British nurseries a boost and protect ourselves a more from diseases swiftly winging their way towards us. There are new threats to London plane, oaks, larch and horse chestnut to name a few. It is definitely a wake-up call. Derek points out that they do not think Chalara kills the ash roots: the trees may regenerate. Ash were once commonly coppiced and pollarded. It is difficult to spot the disease on large trees with no leaves as the lesions are on recent shoot growth. On young trees, with the new growth nearer eye level, you can see the brown-black staining on the newer shoots. Excellent pictures are available on the Forestry Commission's website, forestry.gov.uk/chalara. Check all young trees for symptoms immediately and ring the Chalara helpline (08459 335577) if you see anything suspect. Send an email with a good reference and your contact details to ddasah@forestry.gsi.gov.uk, then clear up and destroy (burn) all the leaves and new growth. New infections can only occur through the leaves so no new outbreaks will occur until spring. Infected trees with the lesions could spread within the tree though, so remove the infected branches, if feasible, and burn. Keep checking the Tree Advice Trust website to keep up to date. In spring the symptoms on larger trees will be noticeable as the blackening, wilted leaves hanging on infected specimens will be easily visible. If mature trees have been infected, ideally they need to be felled. Again, the infected twigs and branches need to be burnt. So far no one has found the fruiting bodies of the fungus (which causes the disease to spread) on wood that is stored. So dead wood could contain the mycelium (roots) of the fungus which you could store and burn at your leisure. It is the leaves and twigs that need to be destroyed. Contact the Tree Advice Trust to send you its free "Tree Damage Alerts." Derek reminds us not to plant monocultures but to widen our selection, even to carry on planting ash, maybe just 10 per cent of the mixture. Other good trees to plant are natives such as beech, birch, field maple, hornbeam, wild cherry and oak. So I am ordering more trees to plant among my shelter belts where I can. They, hopefully, will start to thrive where my ash might fail.