Ash dieback and our approach

Ash Dieback, also known as Chalara dieback of ash, is a serious fungal disease that is killing ash across Europe. Ash is a very important tree in the UK so this disease is causing great concern about the damage it will do.

The disease has spread to some of the University's A tree with ash diebacktrees and we are currently inspecting our ash trees to understand how many are affected. Ash trees make up around 6% of our 10,500 trees so this disease is a significant issue for us.

Once the trees have been inspected, we will develop an action plan and policy to help guide us to tackle the issue over the next 5 years.

We are currently working with the Forestry Commission, the Peak District National Park and other partners establish an Ash Dieback steering group to help share best practice and support throughout the region in tackling the problem.

We will be engaging with community groups such as Sheffield Tree Action Group (STAG) to ensure our plans and policy are as transparent as possible.

Ash Dieback FAQs

What is Ash Dieback?

Ash Dieback, also known as Chalara dieback of ash, is a serious fungal disease that is killing ash across Europe.

It blocks the water transport systems in trees causing leaf loss, lesions in the wood and on the bark and ultimately the dieback of the crown of the tree.

This disease was first described in Poland in 1992 and has since swept westwards throughout Europe. It was first identified in Britain in 2012 in nursery stock then in the wider environment in 2013, although it could have been in the country much longer. The number of confirmed findings is continuing to increase.

Young trees are particularly vulnerable and die quickly once they succumb. Older trees can be slowly killed by a yearly cycle of infection. Spread of the disease in the UK is most likely to be as a result of the planting of infected nursery stock and wood but wind borne distribution of the fungal spores also occurs.

Why do we have Ash Dieback on campus?

We do not know exactly where this infection has come from. The disease was first identified in 2012 in Britain but has taken its time to spread across the country. The disease is spread via airborne spores which are carried via the wind over tens of kilometres.

Prior to the ban in October 2012 on the movement of ash trees, spread over longer distances was likely to have been via the movement of infected ash plants.

What is the University doing about it?

We will be inspecting all our ash trees for Ash Dieback disease. Trees that are affected are being closely monitored to make sure they are safe, but we will have to fell a number of trees.

Why do they need to be felled?

Trees suffering with the disease will eventually die or become weakened over time. Weak trees may cause damage and become a hazard to our students, staff, the general public, buildings or vehicles.

What are the symptoms of Ash Dieback?
  • Dark lesions – often long, thin and diamond-shaped – appear on the trunk at the base of dead side shoots
  • The tips of shoots become black and shrivelled
  • Blackened, dead leaves – may look a bit like frost damage
  • The veins and stalks of leaves, normally pale in colour, turn brown
  • Saplings have dead tops and side shoots
  • In mature trees, dieback of twigs and branches in the crown, often with bushy growth further down the branches where new shoots have been produced
  • In late summer and early autumn (July to October), small white fruiting bodies can be found on blackened leaf stalks.
Who do I contact if I am worried about a tree on campus which may have the disease? Please contact Alan Henderson, alan.henderson@sheffield.ac.uk
Will the trees be replaced? Our policy is to replace every tree we have to fell with at least two other trees.

We will be updating our FAQs but if you have any further questions, please contact us.