Author Topic: What causes oak trunk to thicken and sprout? (Read 2147 times)

Steph Hen · « **on:** March 14, 2021, 08:48:47 am »

We have some lovely trees and oaks. Some have this condition where the trunk and main limbs have thickened bark, swollen and with many sprouts. I think I looked it up years ago and found it was caused by a beetle but today my searches just yield endless tales of other oak diseases but nothing on this. Do any of you good people know what it is please? Will try to upload a photo.

Fleecewife · « **Reply #1 on:** March 14, 2021, 01:02:29 pm »

Hi Steph. It's really hard to see from the pic, but it looks as if the tree is developing burrs, but a lot of them. That does imply some kind of damage to the trunk - insect or fungus - which is causing this reaction. Burrs are produced to protect the tree from some kind of attack. I think they are also produced when new sprouts go a bit mad or cancerous and overgrow erratically. Depending on the cause, it may or may not damage the trees it's affecting (sorry, I know that's not exactly helpful)

Perhaps you should contact the Woodland Trust for advice and maybe a visit when possible.

The upside is that later on you can sell the burrs, once they've grown BI-IG, to wood turners to make really interesting bowls

Fleecewife · « **Reply #2 on:** March 15, 2021, 01:39:53 am »

On the report of the Clapham Common demo tonight, it showed an oak (I think) with what I think your pic is showing, except all the shoots had been trimmed off - it looked like lots of small burrs, with a dip in the middle of each. Next to it was another tree with a larger burr, so perhaps they are the same. Perhaps too it helps to trim off the shoots?

Steph Hen · « **Reply #3 on:** March 15, 2021, 08:04:23 am »

Thank you Fleecewife :-)

It seems it’s nothing too bad, and could be quite exciting for the eventual timber crop.
It was the terminology which was stopping me get any further. This is one big limitation of google vs a big book on a topic. I could read a chapter on conditions and disease of trees, but online, without the term burr, just returns endless stories of sudden oak death and all the other diseases of our trees. I do have books, but forgot to use them! (Also forgot the term burr; memory isn’t what it used to be!)

Fleecewife · « **Reply #4 on:** March 15, 2021, 01:16:41 pm »

I only know about burrs (burl in US) because of the wood turning aspect. I do know about the difficulty of remembering certain words. For me, I'll know the word, but by the time my fingers go to type it, it's gone and takes a minute or two to come back. Nothing new, I've always been like that since long before I got old

arobwk · « **Reply #5 on:** March 15, 2021, 04:13:46 pm »

Having believed that burrs were a natural aberration on some trees resulting from internal chemistry just going a bit wild 'naturally' (some apple varieties, for example, are very much more prone than others) I went off to double-check before commenting. Well, as I'm sure you've also found, @Steph Hen from your own web-searches, the consensus is that actually some sort of trauma (biotic or abiotic) has probably made the tree/s produce a burr/s. Normally nothing to worry about: one commentator did however suggest that really really large (abnormal) burrs will reduce a tree's trunk/branches ability to resist heavy winds.