Aggressive disease to kill off almost all of region’s ash trees within 20 years, report states

File photo of a research at the John Innes Centre, Norwich, investigating the affects of Ash Dieback Disease. Photograph: Simon Parker (Image: Archant)

And in the past year alone, the number of ash trees in Norfolk considered healthy has decreased by 12pc.

The findings are included in a progress report after the second year of a three-year investigation into the extent of Ash Dieback Disease in Norfolk, which is one of the first projects of its kind in the country.

Anne Crotty, Norfolk County Council's senior arboricultural and woodland officer, said: 'Our 20-year strategy will be looking at how best to deal with the trees as they decline and how to recover the landscape. This is happening right across the country.'

Data gathered will be analysed by the Food and Environment Research Agency (Fera) to see if any trends or correlations could be identified.

Ms Crotty said: 'They will look at the statistics and that will help us identify any hotspots that we will be dealing with over the next 20 years.

'We suspect there is a correlation with soil water as ash trees tend to suffer from the disease more if they are in wetter soils.'

MORE: The £20m plus bill to prevent diseased trees falling on roads and at schools in Norfolk and SuffolkProject workers have so far looked at ash trees on A and B roads and HGV routes which accounts for about 19pc of Norfolk's road network. It is estimated from this work that there are roughly 196,000 ash trees lining Norfolk's roads. Ms Crotty said: 'Between 2016 and 2017 the number of trees that are healthy has gone down by 12pc.

'The rate of decline due to the disease is going up slowly, but this is for roadside trees only. Woodland trees appear to be affected much more rapidly.'

Ash Dieback Disease is caused by the fungus Hymenoscyphus fraxineus - formerly known as Chalara.

Ms Crotty said: 'It's a fungus which has come from beyond the Urals that has evolved with a different species of ash. During the past 20 years the disease has spread across Europe. Our European ash trees don't have any defence against this disease.'

Ms Crotty said as well as concern for the trees themselves, the council also had to consider the danger to public health dead or dying trees could pose through falling onto roadways, property or people. She said ash was the second-commonest species of tree in Norfolk, after oak.

The Ash Dieback Project update will be received by the council's environment, development and transport committee at a meeting at County Hall on November 10.