It's not neglect, it's our love of planting trees that has caused this disaster

Is the ash tree doomed? It looks like it. Ash dieback, spread by Chalara fraxinea, a fungus invisible to the naked eye, is now firmly rooted in Scotland and England.

Something might have been done in time but it wasn't. Hopes of preventing its spread now are as vain as Canute's attempts to turn back the tide.

Future generations might wonder who was to blame for the holocaust of our most graceful woodland tree. They might point a finger at the hapless, failed guardians of our woodland heritage, Defra and the Forestry Commission. They would be wrong. What is about to cause the worst disaster in woodland history is not so much law as love. Everyone loves a planted tree. We thought planting trees was the solution but it wasn't. It was the problem.

Remember sudden oak death a few years back? Or the fungal disease that is killing rare wild juniper in northern England? Or the bleeding canker that had polished off two million horse chestnuts even before the tiny moth was turning them brown by midsummer? Or the waterside alder, one in five of which are dead from disease.

The elms, of course, are long gone. I could go on. Name a tree and I'll show you a disease. We have become an unfriendly place for trees. And where did this epidemic start? More often than not, with imported trees. No one has been more outspoken about the coming horror than the Woodland Trust, a charity which manages more than a thousand woods across Britain. No one has been a more enthusiastic planter either.

"We are passionate about planting," they say. True enough, they have planted 32 square kilometres of trees so far and aim to plant plenty more. Someone should ask them where they got their stock from.

Most planters buy it from nurseries. And most nurseries get their stock from abroad – in the case of ash, from Holland and Hungary – rather than grow them from local seed. And guess what: one of the places where ash dieback was first found is the Woodland Trust's Pound Farm estate in Suffolk. Penny dropped yet, Woodland Trust? Still feeling quite so passionate?

Maybe, just maybe, we will be more careful about where tree-planting stock is obtained in future. Perhaps we will create more home-grown nurseries and screen them better. The tragedy is that we need not have planted a single imported tree. Every British ash tree produces masses of seed. We could have potted up any of millions of seedlings growing in any ash wood. That way we might still have had ash trees to admire in 20 years' time instead of piles of wood ash on the bonfire.

Peter Marren is the author of 20 books on nature and nature conservation