IT may have gone quiet over the past few years, but the seriousness of ash dieback, which first hit the headlines in 2012, still lurks and has reached the Dales.

Ash dieback disease has spread “phenomenally quickly” right across the Yorkshire Dales National Park, hitting its most treasured and ancient woodlands, the park authority’s senior trees and woodlands officer, Geoff Garrett, has said.

Detailed in a Yorkshire Dales National Park Authority blog, the effects of the disease cannot be underestimated and the fact there has been little said about it doesn’t mean it has gone away.

Infected young ash trees can be seen on roadsides verges all around the area as well as in woodlands.

As native trees go, ash is hugely important to the landscape. Ancient semi-natural woodland covers about one per cent of the Yorkshire Dales National Park. About 80 per cent of this woodland is made up of ash, making it the iconic tree of the Dales.

The National Park Authority has responded to the spread of ash dieback by removing ash from all tree-planting schemes.

There is currently no cure for the disease.

Mr Garrett said: “The confirmed arrival of ash dieback disease in 2012 prompted a spate of news coverage but many people won’t have heard much about it since then. I think it’s important to raise awareness of how quickly the disease has spread.

“Ash is the dominant tree in the Park’s ancient woodlands, supporting a very special cohort of plants and animals. Over the next 20 years the disease is going to have a devastating impact, so much so that ash will likely become relatively minor in the landscape. Mature trees will take decades to die, but young trees are being killed off very quickly.

The disease is a chronic fungal infection called Hymenoscyphus fraxineus which has blown in to Europe from Asia and is having an impact on the biggest native woodland in the national park, at Grass Wood, near Grassington.

Tell tale signs are a lozenge shaped scar at the base of branches which have died back.

“Grass Wood is an incredibly important ancient semi-natural ash woodland, partly because it has been there so long – probably since the last Ice Age – and partly because of the cohort of plants and animals that it supports,” Mr Garrett said.

“Ash dieback will create opportunities for other trees, but other trees won’t have the same qualities as ash – the same dynamic of light intensity.

“The thing about ash is that it takes forever to come into leaf, then at the first hint of a frost in the autumn, all the leaves drop off. This means certain plants can thrive such as water avens, St John’s wort and celandine. Dog’s mercury and herb paris grow in Grass Wood – plants which take many years to spread. It is this mix which makes an ashwood so special.

“You’ve got to be careful when diagnosing ash dieback,” said Geoff, “because ash trees can die of all sorts. When ash dieback was first confirmed in Britain, many people rang us up to report cases, but they were often mistaken. They’d seen ash trees suffering from canker or wind damage.

“A single, isolated ash in a field is unlikely to be affected by dieback. The wind will blow away the fungal spores before they can settle. It is ash woodlands that are most heavily affected because of the high loading of spores in the air.”

“There is little we can do to tackle the disease itself, but there is a lot we can do to manage the decline of ash trees by making sure that the spaces they leave are filled by other native trees.”

For the ash tree lover, however, there is hope.

Mr Garrett added: “Over the years, our tree planting schemes in the national park have been ash woodlands. But we’ve always planted a mix, using hawthorn, holly, hazel, alder, and sometimes oak. So even if we lose the ash out of the woodland we’ve planted, we’ve still ‘future proofed’ and got the right structure of trees when and if ash makes a comeback.

“The vast majority of native woodland in the Yorkshire Dales National Park is ash woodland on limestone. The ash is the dominant tree, just as it is in the Lake District and the Peak District. From a landscape perspective, the ash is absolutely iconic. Losing it will be nothing short of disastrous. Big trees with big trunks will last longer. It could be years before we see them dying back.

“Ash trees are not going down without a fight, but the consensus is that they are losing the fight. The disaster will unfold over the next 20 years or so.

“But it may well be that ash keeps regenerating and dying – over and again – until the ‘Darwin effect’ kicks in and trees with immunity begin to grow.

“Important research is being carried out by the Forestry Commission to try to identify and develop ash trees that are most tolerant to the disease. My expectation is that some ash trees will be resistant to the disease.”