Saturday, October 27, 2012

What can we do about ash dieback?

The idiot Government has finally banned imports and movement of ash trees, having been aware that the new disease caused by the fungus Chalara Fraxinia emerged in Poland in 1992, has been spreading across the Continent, and was first identified in the UK in February of this year.

Owen Paterson, the right wing climate change lukewarmist who is regrettably occupying the post of Environment Secretary, has put forward a poor excuse for his delay by saying that imports do not occur in the summer. By banning in February, he would have been more certain of blocking any unseasonable movements, not to mention inhibiting domestic movements.

It is possible that outbreaks are occurring in East Anglia and the eastern coast as a result of spores being blown across the North Sea. This should not cause us to roll over and give up any attempt to stop the spread of the disease, for reasons given below.

The fact is that the Government, for ideological reasons, does not like interfering in the market, and as a result, we could face the demise of one third of our woodland, some 80 million ash trees. Thank you, Mr "Greenest Government Yet" Cameron.

As things stand, the disease has been found in several nurseries in the UK, and in some wild woods.

So what do we do now? 

Experts sound as if they are resigned to a massive wipe-out of our ash populations. Denmark has suffered 90%. It is possible that some trees may get immunity to the disease. This did not happen with Dutch Elm disease, because the elms did not reproduce sexually, but Ash reproduces sexually, and experience on the continent suggests that 3-5% will be immune.

Others are prepared to wait for advice about what to do from Forestry Commission scientists. Unfortunately, it appears that scientists know nothing about how far the fungal spores can spread from an infected tree.

We cannot wait around. It may take years to get any certainty about what works. Are we to stand watching the fungus spread from tree to tree while we wait for the scientists to get their ducks in a line? No. Action itself, if methodically observed, can be part of the scientific process. Government palsied inaction can be the control, and reasonable swift reaction can be the measured intervention. Let's see which is more effective.

First, we all need to be able to identify the disease. We cannot rely on arboriculturalists and Forestry Commission workers to keep an eye on every tree in every forest. We must all be vigilant when we are out walking.

Ash trees are easily identified by their leaves:

Chalara puts brown marks on the leaves:

Note how it spreads towards the central vein.

Later, it travels down the leaf pedicle to the twigs, branches, and bole, where it leaves a scar around the base of the infected branch:

Adult trees die slowly, and diseased trees will show dead twigs above the crown:

Some mature trees may lose a few branches, and then overcome the infection.

There is a full page of symptoms on the Forestry Commission site here.

If you think you have spotted a case, phone one of these numbers :

Forest Research Tree Health Diagnostic and Advisory Service
T: 01420 23000;

Forestry Commission Plant Health Service
T: 0131 314 6414;

Right. We've spotted an outbreak. Now what happens?

Left to themselves, the authorities will faff around and let the disease rip until the UK has lost 90-100%  - one third of our woodlands. Not good.

What they should do if they had any sense is to fell any diseased trees immediately. That is what I am going to do if any disease appears in the ash on my land. I am also going to fell any contiguous trees, even if they show no signs of the disease. I will fell without any compunction, because the trees are going to die anyway, and the wood and leaves from healthy trees are safer and more useful than wood and leaves from a diseased tree.

[Update Jan 10 2013: This may not be right: diseased trees may recover, and in felling a diseased tree at the first sign, we may be felling a potential survivor. However, a felled ash tree will grow again from the stump. This is what happens in coppicing. The question is - will these new shoots be more vulnerable to disease than the main tree?]

The only question is - how far out should the circle of contiguous felling extend?

This we do not know. How many spores are shed before the diagnosis is made? We do not know.
How many will be shed from a felled tree? We do not know, although we can reasonably guess that Chalara Fraxinea, being a pathogen of living plant, will cease to function on a dead plant.

The final question is, is it possible to spread the fungus by burning it?  This is very possible. Despite ash wood's well-known ability to burn without being seasoned, if the tree is in leaf it will be a damp, smoky fire. A fire will have a hot, destructive core, but the smoke contains much steam and vapour, and it is quite possible that viable fungal spores could be taken aloft, intact and viable, in the smoke. Again, detailed research is needed.

An alternative to burning is to cover the pile of leaves and branches and allow them to dry before firing them.

There may be good advice from the experience on the continent, and I will update this blog as and when I find out more.

So back to what we do.

  • If we identify it, then report it.
  • If identification is confirmed, then the landowner should fell the tree, and any contiguous trees.
  • The area of the outbreak should be intensively observed, and a further cycle of felling should take place if the contagion spreads.

This is a reasonable, sensible plan, but Government and the Forestry Commission will block it. Not because there is some devilish conspiracy, but because they are stupid, and have proven themselves to be stupid by failing to ban imports in good time. I will apologise publicly if they prove me wrong.

We cannot and must not wait for Government to act. Local Authorities NGOs and landowners should take direct action. This will need an intensive programme of education. People do not like to see trees felled, but they have to learn that felling is the only way to stop the disease spreading across the whole country.


PS One reaction from the idiots will be " We cannot afford to pay for the large amount of work called for." Yes we can, with the GWS.


Chris said...

Just read your call to action on ash dieback. I'm afraid that experience has shown that once a fungal disease is present there is no stopping it. Here in the states we've suffered through Chestnut blight, White Pine Blister Rust, and Dutch elm disease which fundamentally altered our forest ecosystem forever. I've looked to see if anyone here is tracking the progress of the disease as it is sure to arrive at some point in the future but no one seems concerned yet. Another case of too little government action too late. I wish you all luck in saving your forests.

DocRichard said...

Hi Chris
Thanks for the info.
My point is that by felling early, and felling a ring around the case, we will at least be getting some use out of the felled trees. They can be moved to sawmills or even to biomass burners, to extract some energy. Such movements would be dangerous for diseased timber and brash.

Felling of contiguous trees could arguably slow the progression of the disease. It is a slow death anyway, with mature trees lasting a few years. And of course, in areas where trees have been felled, thousands of new ash will spring up. Some will succumb, but hopefully, eventually, some will prove to be resistant.

Good luck in the USA. Make sure that your guys are not asleep, like ours were :(