tree rot
By Woodyer
wiltshire,
United Kingdom 
I have a mature, tall silver birch with recently discovered rot in the main trunk. About 15 foot up the main trunk it splits into two branches. I suspect years ago there was a third at this same level. I had a treeman in taking a lower branch off and he noticed a short rotten stump in the "V" between the two branches. When this was removed he found rot down into the main trunk. He scooped this out to find the extent of the damage, which is basically now a hole several inches in diameter at the top and going down some 15-18 inches into the trunk.
Discussing measures to retard further rotting, and preserve the life of the tree (I don't want to cut it down just yet), I came up with filling the hole with concrete, which he conceded he had heard of, but wasn't too keen on (he thought the lime in a concrete mix could be counter-productive). He proposes pouring a large can of Arbrex in, waiting until it solidifies, then adding more cans in stages until the hole is filled, and finally sealing with a top coat of Arbrex.
Any advice?
25 Jan, 2009
Answers
Fill the hole with fine tarmac, put support tie well up the other two branches.
Arbrex is a tar based product and would be very expensive for that size hole.
25 Jan, 2009
I agree with Spritzhenry. It sounds like you treeman knows what he's doing.Talking from experience I suspect this tree is on its way out and it may be time to bite the bullet and take it out.Think of it as an oppotunity to plant a new tree (or two),also do you know what caused the rot. Ask your treeman to check for honey fungus.
25 Jan, 2009
Thanks all. Re. Spitzhenry, my treeman a good worker and spotted the possible problem, but not (I believe) a "qualified tree surgeon", hence my seeking second opinions. The tree's not that far gone that it won't last a good many more years, Rbtkew, (my treeman's view as well) and there's no honey fungus. The fine tarmac sounds plausible as an alternative to Arbrex.
Woodyer
25 Jan, 2009
You might try talking to the tree officer at your local council and get his advice
25 Jan, 2009
Hmm! Trouble is, Andrewr, tree officers tend to have "views", like the advice from "elfnsafety" angle would probably be take it down!
Woodyer
25 Jan, 2009
Silver birch is not a particularly long lived tree, unlike oak, beech etc. So it could simply be at the end of its life.
27 Jan, 2009
this happened to my 2 silver birch and they were about 45-50 years old. the culpret was honey fungus and had to be removed. have found the RHS advice fantastic for other things to grow in the space.
12 Feb, 2009
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If your treeman is a qualified tree surgeon, then I would be inclined to take his advice. Ours is very knowledgeable and has the best of the trees at heart when he gives advice - he doesn't just say what he thinks we want to hear. If you trust him - there's your answer, Woodyer!
25 Jan, 2009