THOUSANDS of Scots pine trees are being attacked by a deadly infection that had gone unnoticed in the UK's woodlands. 

Researchers believe Curreya pithyophila is likely to have been imported and is now "here to stay", having been confirmed in Scotland and at one site in England. At present, there are no Welsh findings, but forestry officials fear the fungus will move south. 

C. pithyophila grows between the inner and outer bark of the pine, pushing up the outer bark. This space traps tiny insects called adelgids, which feed off the tissue of the trees. The insects are a common and typically harmless occurrences on pine, however when trapped beneath the bark they can be deadly.

With protection from adverse weather conditions and predators, the insects reproduce at pace and stay in a confined area, feeding to the core, sucking the health out of the branch and leaving an exposed wound. The vulnerable site is then seized upon by a known native fungus that does the final damage of killing the branch. The fungus then gradually moves along and up the other limbs of the pine, leaving dead branches in its wake.

Experts only noticed the issue after a report of unusual symptoms of cankering, where a destructive fungus damages the bark, on Caledonian Scots pine in October last year. 

Dr Sarah Green, a forest pathologist at Forest Research, told the Times: “I had never seen that level of cankering in Scots pine, and almost every pine I looked at in Cairngorms had it — a black, burst-open bark.

Forestry Journal:

“When I looked at it under a microscope, I peeled back the outer layer of the fungus and underneath I was quite shocked to see all these immature insect bodies writhing away under the heat of the microscope light.”

Described as "obscure" by Forest Research, the fungus has only occasionally been mentioned in academic papers, and it reportedly did not produce any match on a global database. 

Dr Green added: “It’s here to stay. You cannot stop something spreading that is already so widespread. It’s yet another thing that’s affecting our trees … we’ve had a lot of invasive pests and pathogens coming in.

“If we do prove this was an introduction, I think it’s another example of poor planting material, things coming in on traded plants. I’m hoping that it will only result in a slow debilitation of trees, rather than an outright killer. But we don’t know what it’s going to be like in 20 years' time.”

Forest Research has called on the public to report infections in England and Wales through its “Tree Alert” service.