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Capricorn beetles and large oak trees


David
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We have, or had, three very large oak trees in our garden.  Last week one of the trees, which did look rather sickly, fell down.  The root system was exposed showing that there were no roots left, all having either rotted, or been eaten away.  We are now cutting it up for firewood.

While cutting it up we have found that it had been extensively attacked by capricorn beetle.

The second tree also looks rather sickly, and we have found evidence of capricorn beetle, so it will be felled soonest.

Both of these trees had never been pruned, so the trunks are large and straight.

We have a third tree which at some point in the past been pruned (or pollarded?) at about 12 feet above the ground.  Now it has a thick trunk to about 12 feet high, and above that there are many branches reaching to the sky.  It is about perhaps 70 feet high, and very beautiful.  This tree is very close to the house, and also the overhead electricity supply to our house and the adjacent farm (the wires go through the tree branches).  If this tree falls it could be very dangerous.

After finding capricorn beetle in the fallen tree, we inspected the third tree and found about a dozen exit holes of the capricorn beetle in the trunk.  The tree looks generally healthy, and produces lots of acorns, but there are the first signs of distress in that some branches seem to have died at the ends, and have reduced leaf cover. Similar to the other two trees but not nearly so advanced.

I wonder if there is anything we can do to protect this tree from the capricorn beetle, and also what is the life expectancy of a large oak tree after capricorn beetle infestation.  How safe is the trunk?

I have tried a google search, but apart from many gory photos of the beetle, nothing tells me how to protect the tree, or what the tree's life expectancy might be.

Many thanks,

David

 

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David, are you sure that it's Capricorne beetle that's the problem? There's no evidence that I know of that would suggest that capricorne (Hylotrupes bajulus) would attack oak in this manner, the species has a preference for softwoods, a large number of telephone poles were / are attacked.

If you have any photos it would be useful if you could post them on the forum, either of any beetles that you have found, larvae or the damage to the trees.

Perhaps I should add that the root system damage indicates something else.

Chris

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Unfortunately we are pretty certain that it is the capricorn beetle, or cerambyx cerdo linnaeus of the Great Capricorn Beetle family hexapoda>coleoptera>cerambycidae family which does live in oak.

Having been told by the locals, and two tree surgeons, that it was a capricorn beetle I looked it up on the internet.

This morning we started cutting the branches of the fallen tree, and found some galleries.  I have not yet taken photos as it was raining and I didn't want to get my digital camera wet.

We have not seen a beetle yet, only the exit holes and some galleries, and these are exactly as shown on the web site www.forestryimages.org and www.forestpests.org .

This morning through google I also found a thread on the subject in the total france forum, of which I am not yet a member.

No real advice though as to how to protect the tree, or how badly damaged it might become.

I do agree that the root damage is separate from the capricorn beetle.  We have now found out that before buying the house, the first two trees were surrounded by maize for several years, with enormous amounts of watering.  Thus the locals feel that the roots rotted because of too much water in the ground.  Possible, but as well as rotted roots, we have found hollow roots which appear to have been eaten.

The third tree was not surrounded by maize, so we are optimistic that the roots may be sound, but we are concerned about the capricorn beetle.

Thanks for your reply.

David

 

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Hi David, That was the species that I indicated on Total France, and it's common name is, as you say, in France is Grande Capricorne, but not the beetle that most people are usually speaking of when they use the word Capricorne (as in Capricorne des maisons)

It is in fact a species in severe decline, listed in France as a species to have habitat protection and a close eye is being kept on its population levels, so although you may not think so, you are in fact rather fortunate if that is what you have.

I really would appreciate photos of any beetles 'dead or alive' that are in the direct vicinity.

I can't really see how having the maize there, irrigated or not, would have any bearing on the situation what so ever, and it's more likely that the roots have been eaten by another species (or several) after the tree has started to die.

What's the situation like with other oaks nearby and is it a wooded area, or just odd trees here and there?

Chris

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Hi Chris,

We have been cutting up the fallen tree today, and have finished cutting the branches into 50 cm lengths.  We have not yet started on the trunk.

There is a lot of good solid wood in the branches, but also a good many branches are in poor condition.

We have found some beetle runs and chambers on the cuts, but not as many as we expected.  We have not seen any beetles or grubs yet.

We had quite a wet day today, but I managed some photos.  Tomorrow I hope to take more photos, but it is difficult for me to rake around the cut off pieces as I have to watch from afar.  The neighbours are being wonderful, and are cutting up everything in sight, but they are not looking for beetles.

I had another look at the tree we hope to save today, and it has the same exit holes in the trunk as the exit holes we have seen in the branches of the fallen tree.

I too suspect that there is more to this than meets the eye.

Could you send me a private message with your e-mail address so that I can send you some photos (I haven't mastered the art of photo posting on this forum yet).

David

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Chris,

I should have said that this is a cattle raising area, so we have fields of grazing cattle or growing maize.  Each fairly small field is surrounded by hedges with mature trees, many of them oak.  We have three large oak trees in our garden which could be described as odd trees here and there.  All our trees are exposed to weather and sun.  We do not have any wooded areas nearby.

David

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David, You can e-mail me at [email protected] .

Have you looked at Phytophthora ramorum?  I just find it strange that an oak should succumb to a few (or even a few hundred) beetle larvae holes, they are a very robust tree and can happily live with a huge hollow more than half way through the trunk. The fungus is interesting, and recent in Europe, but if this is what you have it needs containing.

If any of the photos are interesting, I'll post them on the forum for others.

Chris

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Chris,

Many thanks for your latest post.  I have looked in the web for Phytophthora ramorum and it is very worrying.

I have sent you some photos, and two of the photos seem to show this in the third tree we hope to save.  There are also signs in the second tree to be cut down, but I could not find it in the fallen tree.  However, access to the fallen tree is difficult.

As an aside we have a large laurel hedge near the third tree, and last winter one of the plants forming the hedge suddenly died.  The rest seem healthy.

We have noticed some discoloured leaves, but thought no more of them.

David

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Photos first.....these are some of the photos that David has sent me, I have put my comments, but this is only my view.

Above. appears to show bark where the tree is injured or diseased.

Above. apparently tunnels or chambers, it may be that the orange brown area at the end of one of them is fungal.

Above. Again tunnels / chambers, again orange brown staining and it would seem that at the right hand edge the bark has lifted from dead or diseased wood.

Above. Exterior bark photo which I think is an infection.

Again, I find it hard to believe that a mature oak tree can be killed by some beetles, normally a tree "heals" around these cavities, the most important place for a tree is the bark, and even with this huge areas can be removed, as long as they don't encircle the trunk completely, and the tree will survive, especially oak.

I think that you should consider getting in touch with INRA, David, and let one of their experts have a look at it, I think that Pamproux may be you nearest research establishment, if it is serious, quarantine and destruction of infected wood in situ may be the course of action.

This is all somewhat speculative, but I think that better safe than sorry is the correct course of action.

Any other comments?????

Chris

 

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Chris,

I do agree better safe than sorry.  I have looked up INRA on the internet but could not find anything about Pamproux, or any contact details.

I am afraid that my french is very basic, and I could not hope to hold a phone conversation on this subject in french.

I had thought of going to the Marie, but it is a small village, and as you said earlier in this thread they will probably just say capricorn beetle.

We live in North Deux Sevres near Bressuire.  Is there anywhere nearby that we could take some photos for an initial opinion.

If quarantine and destruction of the infected wood in situ is recommended, would this include all the wood from the affected trees (we were hoping for some firewood), and who would pay for it?

Thanks,

David

 

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There's alot that could be happening here, to identify the various pathogens that might or might not be happening would require a thorough eximation, unfortunately a few photos doesnt really give the full picture. Most certainly there is insect activity and bacterial wetwood, if the tree is old then it's just succumbing to what all old beings suffer from...old age!
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Sorry Chris.H.  I should have mentioned that the trees, as far as I can tell from another photo, are not exactly veteran, David will correct me if I'm wrong, but I would guess at 80 to 120 years old, not a great age for an oak, the one that remains is well formed and upright.

David, I'm not sure what to suggest, I could try to get the photos to someone at the National Forestry Office in Poitiers tomorrow, it may not be easy, but I could have a go. They are in the same building as the LPO, who I know rather well!  They at least may give a better informed opinion.

I'll telephone in the morning, it's an excuse for a day of work and I had a long, if productive day today.

Anyway I'm intrigued now.

Can you e-mail me your telephone number?

Chris

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The 200 year-old oak tree in our orchard fell down the other week, taking half of our even older bread oven with it. It had the same kind of  damage you describe all the way through the middle of it, and the roots didn't seem to be very substantial either, so maybe it is the same thing.

Our neighbours tell us that there is a disease spreading amongst oak trees in the south of France, and that in 20 or 30 years there won't be any oak trees left in the south - perhaps Chris has heard about this?

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Thanks Chris,

I am not an oak tree expert, but I would agree that the trees do not seem to be very old.  I would estimate 80 to 100 years, or perhaps less.

I have sent Chris pp an email with my contact details, as I think it might be worthwhile getting an expert opinion.  The third tree is close to the house, and I would hate for anybody to be hurt by a falling tree, or a falling branch.

David

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I am very sorry to hear thet you are not keeping well, I hope you have a quick and full recovery.

Please do not rush on this matter on my account.  It was very kind of you to offer to help and I value your help and assistance.

I have been looking at the trees again, and I think that you may be correct that, although we do seem to have capricorn beetle, the main problem seems to be a fungal or virus infection.  We are told that London is also having problems with trees suddenly falling down because of "bleeding cankers" caused by infections.

I am less worried about the two remaining trees suddenly falling as they both survived the first of the autumnal equinox gales which we experienced last night.  However, I would prefer to ensure that they are safe before the winter sets in.

Get well soon,

David

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David, our tree man called today to cut down a dangerous chestnut tree and he says that Capricon is becoming a real threat for oak trees in the south, plus there is also a Ver (Worm) that is attacking them as well. He says that Capricorn leave "pods" (I don't know the technical term) attached to the tree, and when the young hatch out they burrow into the tree, even into the middle, so all the "channels" you see in the bark of your trees are almost certainly down to Capricorn. he thinks that there is something you could spray the tree with, but it may be dangerous to other wild life. It seems to be a very bad world for the oaks where we live because they also have to cope with ivy strangling them (we cut the ivy roots at the base to kill it) and with some sort of fungal growth covering them (I don't know how harmful this is to them).

As an aside, at the end of the job the tree man was using the biggest chainsaw I have seen (80cms). He had to use his car to pull and finally drop down the base of the tree which was nearly 2 metres in diameter, because it was in such an awkward position that he couldn't completely cut through it!

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Probably not related (I wouldn't recognise an oak tree 'till it started chucking conkers at me) but there seems to be a lot on the internet about "sudden oak death" - type it into Google and you'll see what I mean... but as I say, I have no idea if it's relevant to your situation.

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Tarngranny and Iain,

Thanks.  I think we may have worms and fungal growth, and I have looked at the internet for sudden oak death, and this seems to apply to my trees also.

I am hoping that chris pp can diagnose the problems with my trees so that we can make them safe.  We were very lucky when the first tree fell in that it caused no damage.  However, I had been working under it the day before, and my children had been working under it the weekend before.  This makes me very sensitive about the other two trees.

The remaining two trees could do a lot of damage if they fell, and one could go through our bedroom where we would be if it fell at night.  If it fell during the day it could take out any visitors including the post lady, in addition to our lounge where we might be sitting.

I am waiting for chris pp's reassurance.

 

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David, there's one thing I forgot to mention, a moss (Lichen?) which grows on a lot of our trees and apparently sucks moisture out of them - it's a wonder that they survive at all isn't it? The "secheresse" of 2003 and more recent droughts are also having an effect as well, because the ground is becoming too dry to support tree roots in some places, especially on sloping ground like ours.

My husband has been worrying for a while about the dangerous Chestnut we have just had chopped down and if that had come down on its own it would have even crushed a tank! Another point, the Chestnut had exactly the same kind of disease/attack damage as your trees so it doesn't seem to apply solely to oaks and you should check any other types of trees you have. Don't hesitate about having the trees felled if there is the slightest doubt about them because the old oak tree in our orchard came down without warning during a spell of good weather and would have done tremendous damage if it had fallen towards our house.

Yet another point, I wonder if anybody on the forum has had experience of Insurance claims caused by falling trees and were there any problems? Also, I wonder if an Insurance company would pay for preventative maintenance where a tree needs to be cut down?

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David,  I'm not getting very far in getting any concrete answers, no one that I have spoken to thinks that beetles would be the cause. The prevailing view is that the tree was poorly rooted and went over eventually with a strong wind and soft soil, does this seem possible? Apparently it's not unusual, nor is it unusual to find large internal cavities.

I'll keep on it, but it's not exactly inspiring to get the "shrug".

Chris

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Chris,

Thanks for your post.

I agree that it seems unlikely that the capricorn beetle caused this tree to fall.  Unfortunately the tree fell in a light wind, and the soil was not soft.

The exposed root system was almost non existent, and the exposed roots were either a soft fibrous material (rotten), or were hollow.  We suspect a bacterial infection, perhaps combined with an insect infestation of the roots.

We are now concerned that the other two trees may have the same root problem, but no one we have spoken to can give us a proper answer.

We are therefore going to fell the second tree which looks poorly, and trim the third tree to about half height, so that if it does fall, it will cause little or no damage.

We have also found a large hole in the centre of the trunk on the third tree, at the level of the pollarding.  I cannot get up to see it, but I am told that it is about 0.5 to 1.0 metres diameter, and about 1.5 metres deep.  It is full of soft rotten wood, acorns, and other damp or wet mush.  Some say this is not a problem, others say that because the tree is so large, it may split at the hole.  If so the larger part would fall across the house, flattening the bedroom and lounge, and taking the electricity supply out.  Thus we will trim the tree to a safe height, so if it falls, no one will be hurt, and minimal damage will be caused.

On this post, others have asked if the cost of this might be covered by house insurance.  A very good question, but no answers.  I suspect the insurance would pay for damage if the tree fell, but would not pay for preventative treatment.

Thanks,

David

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OK, this looks as though it may be promising, Phytophora cambivora or Maladie de l'encre. It attacks the roots of chestnut and oak and really does start to look as though it may be prime suspect. The tree starts to look a bit unhappy and then just falls over.

See what you think, David.

Fingers crossed, Chris

 

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