Ash trees are a renowned part of Norfolk’s landscape. You’ll find them along our country lanes, in parklands, and in back gardens across the county. It’s estimated that ash trees make up roughly 12% of broadleaved woodlands in the UK and are home to around 955 species, 45 of which are believed to only ever be found on ash trees.
Ash dieback spread to the UK from mainland Europe, with one of the first cases in England confirmed in a nature reserve in Ashwellthorpe by Dr Anne Edwards, a researcher from the John Innes Centre.
Since the disease first arrived, experts have become more hopeful about the future of ash trees, estimating that 25 – 50% of affected trees could recover from infections.
As qualified arborists, our role is to check the health of your tree and help you understand what to do next.
What is ash dieback, where did it come from, and what does it look like?
Ash dieback is caused by a non native fungal pathogen, Hymenoscyphus fraxineus, also referred to by its older name, Chalara. Through genome sequencing, the fungus has since been traced to Japan, two years after it was first identified in the UK.
Much like the disease name suggests, an infected tree shows signs of dieback in the uppermost crown. This looks like thin and patchy branches, with bare, dead twigs at the tips. Many trees also try to make up for lost leaves by sprouting bushy clumps of new shoots along the stem and larger branches.
In the summer, you will see signs of Ash dieback on the leaves of affected trees. Look out for dark brown or black patches, or leaves that wilt and turn back while still attached to the tree. Infected trees often drop their leaves early too.
In younger trees, the condition of the bark is also a good indicator. Ash dieback often causes dark brownish patches shaped like a diamond where smaller branches meet the trunk of main stems.
Summer is the great time to look for suspected infection, as the symptoms are easily spotted amongst the tree’s foliage. Some of these signs can also point to other issues, such as drought stress or a different disease. Before you decide what to do, it’s best to speak to a qualified arborist. They can confirm whether the symptoms you see point to ash dieback, check how badly your tree is affected, and advise on the next steps.
How does it spread?
Ash dieback is an airborne pathogen. When infected leaves fall in autumn, the fungus survives over winter in the leaves on the ground. The following summer, it produces minute white fruiting bodies on the old leaf stalks. They release spores into the air, which land on leaves of nearby ash trees and start the cycle again.
This means trees can be reinfected year after year by spores from the fallen leaves around them. The spores can also travel a long way on the wind, which is how the disease has spread throughout the country so quickly.
People play a part in the spread too. Imported young trees helped to bring ash dieback to the UK and leaf litter carried on boots or vehicle wheels is one of the biggest risks for moving it to new areas, making biosecurity an immensely important process in protecting our native trees.
How serious is it?
Ash dieback is one of the most severe diseases the UK has faced in decades. Experts have compared its potential effect on our landscape to Dutch Elm disease, which wiped out most of the UK’s elms in the 1970s. Woodlands have been hit the hardest, whilst individual trees, or trees growing in open areas are far less affected by the disease.
For homeowners, the biggest concern is usually safety. Weakened trees can become more susceptible to other issues such as honey fungus, which attacks the roots and can make the whole tree unstable. This is a major risk for trees close to homes, roads, footpaths and play areas.
Can a tree recover from ash dieback?
Whilst there is currently no cure for ash dieback, it doesn’t mean every infected tree will die. There’s a big difference in how individual trees respond. Some die very quickly, while others hang on for years, and few stay completely healthy. Young trees tend to die fastest, while larger, older trees can take several years and typically succumb to other pests or pathogens.
DEFRA expects between 1% and 5% of ash trees to have a natural tolerance to the disease.
Closer to home, scientists identified a tree in a Norfolk woodland, nicknamed Betty by Dr Anne Edwards, that shows strong tolerance. Trees like Betty are helping researchers grow new generations of ash that can better resist the fungus.
Projects such as “the Living Ash” Project look for trees with natural resistance, collecting graft wood, and planting with a national archive for further research.
Because the disease affects every tree differently, an infected tree doesn’t automatically need to be felled. Guidance suggests removal isn’t usually needed for trees with up to 50% dieback in their crown. Many mildly affected trees can remain where they are with an annual inspection to determine whether the tree is beginning to recover or whether further maintenance is required.
For more serious cases, pruning affected branches or removing the tree may be the safest option.
Who is responsible for a tree with ash dieback?
If a tree is on your land, it’s your responsibility. Tree owners have a legal duty of care to keep their trees in a reasonably safe condition, whether the tree is healthy or diseased. If a tree drops a branch or falls and causes damage, you could be held responsible.
You don’t have to be an expert. The law only expects owners to assess the risk sensibly and take steps that are reasonable and practical. This normally just means getting a diseased tree checked and following the advice that you’re given.
If you rent your home, check your tenancy agreement. Trees are normally the landlord’s responsibility, but it’s best to let them know about any concerns as soon as possible.
If the tree belongs to a neighbour, it’s their responsibility to deal with it. A friendly chat is usually the best place to start, as they may not have noticed the signs.
For trees on public land, such as parks or highway verges, the responsibility lies with district or local council authorities. A discussion with the local tree officer will help determine ownership of these trees and raising concerns may help them to identify “problem trees” that they were previously unaware of.
What should you do if your tree is infected?
The first step is to get your tree checked by a qualified arborist. They can confirm whether they believe that this is ash dieback, see how far the disease has spread, and look at where the tree is positioned. Depending on what they find, your arborist might suggest monitoring the tree, removing dead branches, reducing the size of the crown, or fully removing the tree.
Ash dieback is never a job to tackle on your own. Infected wood becomes dry and brittle, which makes it unpredictable to cut. Badly affected trees can be too unsafe to climb and may need to be removed from a mobile platform.
You may also need permission before any work goes ahead. Larger groups of trees on farmlands or in woodland may need a felling licence from the Forestry Commission or if your tree has a TPO (Tree Preservation Order) or sits in a conservation area, you’ll need to let your council know or get permission first, even if the tree is diseased. Our team can speak to your local council on your behalf, and as part of our service, we will always check for TPO or Conservation Areas prior to providing your quotation.
Ash trees often provide homes for bats and nesting birds, which are protected by law. A trusted arborist will check for signs of wildlife before starting and plan the work around nesting season where possible.
Can we stop the spread of ash dieback?
Unfortunately, there’s no way to stop ash dieback completely. The disease has already spread across most parts of the country. There are still simple things we can all do to slow it down and protect the trees that are holding on. Experts have said that good biosecurity around trees is key.
If you have an ash tree in your garden, clear up the fallen leaves each autumn. This reduces the number of spores released near your tree in the following summer. When you’ve been walking in woodland or the countryside, give your boots, tyres, and dogs’s paws a thorough clean before you head somewhere new. This helps to stop infected leaf litter travelling with you. The same goes for any garden tools or equipment you’ve used around diseased trees.
If you’re planting new trees, buy from a reputable nursery that provides relevant plant passports. This lowers the risk of bringing in this pathogen or other tree diseases from abroad.
Finally, if you spot signs of ash dieback somewhere new, you can report it through the Forestry Commission’s Tree Alert service. Every report helps scientists track the disease and find tolerant trees.
Worried about an ash tree? Speak to our arborists
Ash dieback is a serious disease, but it doesn’t have to mean the end for every infected tree. Many trees are fighting back, and with the right care, some can stay safely in your garden for years to come.
If you’ve noticed signs of ash dieback, the best first step is to get your tree checked. As qualified arborists, our team can assess your tree’s health, explain your options and help you decide whether to monitor, prune or remove it. We’ll always give you honest advice, even if that means leaving your tree as it is.
We may be able to give advice from a photo, so feel free to send one on Whatsapp. Or, get in touch to book a site visit.
