Each winter, of late, has brought a flurry of scaremongering about the risk of global pandemics with the power to wipe out millions of us.

Yet while we have selfishly fretted over each sneeze and cough, and wondered where to buy germ-repellent masks, deadly diseases have already arrived on our shores. Their victims are not us but various types of trees, but while they may not directly affect human health, in the long term they represent as serious a threat as any new strain of flu.

Ash dieback has grabbed the headlines in the past week, a merciless affliction which could destroy most of the 90 million ashes in the UK. News yesterday that an equally serious threat hangs over the Scots pine was possibly even more disturbing. According to Dr Steve Woodward, reader in tree pathology at Aberdeen University, two foreign diseases which destroy Pinus sylvestris have already reached France, Spain and Portugal, and are but a hop away from our forests. Were either to cross the sea, our most distinctive, emblematic tree would be in grave danger. If both arrived at once, the results would be catastrophic.

Pitch canker and pine wilt are the layman's names for these, the Scots pine equivalent of the bubonic plague. And it's not the only species in jeopardy. Corsican pine, juniper and larch, among others, are also at risk from new diseases. They are all victims of what one government scientist calls "a tidal wave of pathogens", entering the country thanks to a burgeoning international trade in plants, and a warming climate, which allows disease-carrying insects on imported trees to disembark alive and kicking.

The loss of any species of tree is awful to contemplate, but with the possible exception of oaks I doubt any has a more important place in the country's affections than the Scots pine. Its stature, shape and scent are synonymous with Scotland itself, and as the authors of The Heritage Trees Of Scotland write: "No tree symbolises Scotland, and particularly the Highlands, more than the Scots pine." They go on to relate a story about Queen Victoria, who was so enchanted that she bought Ballochbuie Forest, "with the express intention of preventing the old Caledonian pines being sold to an Aberdeen timber merchant".

In the face of impending blight on the scale predicted, it's easy to become hysterical. In fact, I'd recommend it, since otherwise it might be too late to prevent arboreal armageddon. As is becoming clear with the ash's plight, government ministers were decidedly sluggish in taking action to curb its spread. Were the same to apply to the Scots pine it would be shameful, not least since 2013 has been designated The Year Of Natural Scotland, with the aim of promoting Scotland's exquisite landscape and rich ecology. But imagine if, in the run-up to the independence referendum, politicians could not, or would not, save our national tree. What sort of message would that convey about their priorities, as well as their powers?

Those who remember the devastation caused by the foot-and-mouth outbreak in 2001 will recall the gloom it cast. While not to belittle the impact of that disaster on farmers and the countryside, its horror would pale into insignificance beside the massacre of our Scots pines. Once foot-and-mouth is controlled, livestock can be swiftly replaced. Scots pines, which live for 150-300 years, cannot. A field empty of sheep and cattle is an abomination for farmer and onlooker, but it does not reshape the landscape. The felling of trees as tall and straight as tea clippers's masts, does.

In economic terms, the Scots pine is crucial for our timber industry. It's also vital for the wildlife it nurtures. For the sentimental among us, these noble trees are like the guardians of the country's soul, the custodians of true wilderness. To walk among them is to be transported to a more elemental time, to feel a connection with nature that is profound and comforting.

When we were children, our Christmas trees were mostly Scots pines. If rigorous action is not immediately taken to ward off danger, however, there might not be many more Christmases left for these beautiful giants.