Sudden larch death Posted on October 30, 2014

It’s a letter I had dreaded coming: a statutory Plant Health Notice: our larches have caught Phytophthora ramorum and have to come down.

Larches are a major element in our Snowdonian woods, and after the oaks and beeches our favourite trees. Many acres were planted fifty years ago and are, in theory, ready for felling. Larches, though, if they are thinned to a wide spacing, so that their graceful high branches form only a thin canopy, grow on with quiet deliberation for a century, making more and more of their marvellous durable timber. With spruce there is a quite brief window where their trunks are the size the sawmill needs. Leave them longer and the butt gets middle-age spread; a huge log is too big for the mill and goes to waste.

Much of the larch was interplanted with beech from the start. Others I underplanted with Douglas fir as we thinned them over the years. But larches are also some of the most fertile trees; their seedlings are everywhere; pretty pale children of the forest. And we have continued to plant larch, mostly in a mixture with spruce and fir, often with pine and oak, over twenty years.

All of this is under threat. The plant health order says the diseased trees must be destroyed. Their needles are carrying Phytophthora spores. They carry on the wind or in drops of water; they remain on the ground after the lovely golden leaf-fall; the source of infection must go.

Our first question: which trees? They were spotted from a forestry helicopter, looking sick, then confirmed as infected by a pathologist on the ground. He didn’t mark them, though, so we can’t do the logical thing: fell their neighbours within a generous radius. The order says the whole forest compartment must go. That’s almost 25 acres: as though the trees know which compartment they are in. Indeed if the helicopter had taken a different route it might be another parcel.

They can either be felled or poisoned with chemicals. Either is allowed. Logic tells me that felling them and carrying them out of the woods almost guarantees spreading the disease, whereas using herbicides and leaving their carcasses standing at least attempts to contain the spores – even if it costs the (already reduced) value of the timber. Felling all the larches would also damage their neighbours, beech or Douglas and all the beautiful mixed population grown up over the years. As for eliminating the several successive generations of young larch: it would mean a scorched-earth operation.

The authorities don’t know what to do either. Last weekend we spent in the woods, watching the fleeting sunshine light one patch of golden needles, then another, across the hillsides.

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