Ash dieback at Cissbury Ring

Ash dieback on a mature tree

Ash dieback is a growing concern across the country including on the South Downs here in Sussex. This fungal disease is changing our local habitats and we are working hard to lessen its effects.

Many of our young trees on the north flank of Cissbury are ash (Fraxinus excelsior) and as a result many of them will be lost to this fungal disease over the next 10 years.

The effects are already clearly visible in the tops of the trees at Cissbury and ash dieback will certainly change the landscape considerably over time.

As always we will be working to try to make sure that this transition is as smooth as possible in our key habitats. We want to ensure that it has as little impact as possible on the wildlife and wild flowers in the area during this time.

However, due to the sheer scale of the issue, we have already been planning for the potential effects of this widespread disease on Cissbury and our other properties and have built this into our practical tasks and property plans across the whole South Downs.

What you can see on Cissbury now?

The effects on a young ash tree are most noticeable as this disease enters the tree through the leaves and so affects the tips of the branches first. It then works its way down the tree towards the roots so small trees die more quickly.

A close up showing the effects of ash dieback
The effects of ash dieback
A close up showing the effects of ash dieback

The effect on larger trees is still noticeable if you take a closer look. The tips of the tree will have dead twigs sticking out of the canopy. The length of these dead twigs is an indication of how many years ago the tree was infected. Cissbury was one of the sites hit in year one of the fungus arriving in this country so has a lot of mature trees with substantial dieback.

In August to October you may see twigs with retained drooping black leaves. These drooping leaves indicate the twigs affected this season as part of the spread of ash dieback, and next season those twigs won’t grow a leaf at all.

What about long term?

This action of dying back over the seasons means that the fungus will keep moving along the branches, back down away from the tip towards the heart of the tree until it has killed off all the living ash tissue in the tree.

In Poland, where the fungus arrived in 1992, it has been well studied and documented. There and in other European countries there appears to be a proportion of ash stock that is resistant to the disease.

It is assumed this will also be the case in this county so we are looking and watching to see if any of the ash trees on Cissbury match this situation. Hopefully any tree that is resistant will shed seed that is resistant and we will be able to regrow ash from that stock.

It is totally unaffected trees we are looking for; any tree that is showing signs will progressively die back and can reasonably be assumed to have no resistance.

We will continue to clear many of these affected trees but trees that look clear of the disease will not be felled and may well in the future be used as seed trees to help recolonise other woodland areas.