Thousands of trees felled to halt parasite

THOUSANDS of trees are being cut down across Scotland to prevent an outbreak of a deadly fungal parasite which threatens to be the new Dutch Elm Disease.

Record numbers of new cases of Phytophora ramorum fungus have been found in larch trees in Scotland this year, with the number of woodland sites affected up from just a “handful” in 2011 to nearly 150 now.

More than 8,000 trees on the West Coast are currently being felled after the destructive parasite was found to have infected dozens of larches on one estate in Inverclyde. The disease has also been reported in Dumfries and Galloway, Mull, Islay, Craignish, south of Oban, at Carradale, in Argyll and at the National Trust for Scotland’s Arduaine Garden, where hundreds of larch had to be axed.

Land managers hope drastic action will save other plantations from being infected by the disease, which spreads rapidly from tree to tree via wind-blown spores or by being transported by walkers and mountain bikers. The fungus causes the tree’s crown and branches to die back and death can follow within months.

There are concerns that if the fungus is not contained it could hit Scotland’s timber trade even harder if transferred to other species such as the sitka spruce. More than 80 per cent of Scotland’s tree cover is made up of conifers such as larch and spruce.

The outbreaks are being monitored by the Forestry Commission, which has predicted that unless serious preventative measures are taken, Britain could suffer a similar epidemic to the Dutch Elm Disease outbreak in the 1970s, which wiped out almost every mature elm in the country.

Forestry management experts Bell Ingram, which is dealing with the West Coast outbreak, is urging other estates to check their trees for signs of the fungus and take precautions to stop a new  epidemic breaking out.

Geoff Brown, a senior associate at Bell Ingram, said: “The West Coast of Scotland is affected by Phytophthora ramorum which is why we want to raise awareness of it now, so people know what symptoms to look out for and how to minimise the risk of spreading it.

“As larch is a deciduous conifer, it is critical that estate owners arrange to have their crops inspected as soon as possible before the autumn needle drop makes it impossible to identify the infection.

“Although fewer than 100 trees are infected on the estate in Inverclyde, more than 8,000 trees are being felled to contain the disease, which gives you an indication to the scale of how infectious the disease is and the precautions we need to take to try and prevent further damage to other forest areas.”

He also urged outdoors enhusiasts to take care they do not accidentally transfer the disease between woodlands. “What a lot of people might not realise is that it can be spread easily through activities like mountain-biking and dog-walking, as both can involve travelling through different forests with the infection being transferred by footwear or bicycle wheels,” he added.

Phytophora ramorum, which translates as “plant destroyer”, was first discovered to be infecting larch trees in the UK in 2002.

Few trees in Britain were affected until 2009, when it was found to be infecting large numbers of Japanese larch trees in south-west England which had to be chopped down. The following year it spread to Japanese larches in Scotland, Wales and Northern Ireland.

This year, Forestry Commission Scotland has issued more than 140 statutory plant health notices requiring owners to clear the trees in affected areas, which cover 300 hectares in total.

Norman Starks, operations director at the Woodland Trust Scotland charity, said measures to prevent woodland diseases coming into the country from abroad are inadequate. “What controls do we have at our borders for stopping these diseases coming over?” he said. “The answer is, not many.”

Phytophthora ramorum has been spreading up the west coast of Britain for some years as a result of the climate becoming warmer and wetter, first affecting larches in Cornwall and Wales.

It has also been found on juniper trees in the north of England, so could spread north to what is an important native species in Scotland.