Just in case you missed the comments on the blog relating to the branch failure on the Open Masters oak see below. Russell is the Cornwall Park arborist for those of you who not know him.
"Yeah crazy ay. looked 100% fine, on the VTA. at least 10 other climbers had climbed that tree and done the branch walk.
i think it was from an old pruning cut, and must not have healed properly. i will go and have a close look at the wound and have a good inspection, as to why this failed.
but very good point rich, there has been a few oaks with very large limbs shedding. defo good idea to double check ur anchor points the whole length of the limb you are anchored into and more.
anyone got any reason's to why this is happening recently? my guess maximum weight of tree throughout the year? turning to cold morning maybe affect?"
"It hasn't rained in ages and that snap hasn't even torn down the stem much, if at all. The oaks are pretty brittle at the moment. And it did have jono jumping on it and that's a lot of punishment."
"I cannot tell you why this branch failed but I can say that there was on old cut on the top side of this branch with a small column of decayed wood running along the top of the branch.
The branch was very long and pretty much horizontal (exposed to a lot of gravitational force). Also it's never been heavier than the day it broke as we've had good rainfall last winter and lots of heat this summer (long shoot extension).
Looked strong to me though, I would not have guessed it would go, particularly when Z untied his high, central TIP and descended from the end of it!
While I worked in California I saw a number of trees (mainly E. species but some oaks too) which failed during 'classic' sudden summer limb drop conditions. This just didn't really feel like that to me, not hot enough, not dry enough.
If I could add a guess it would be that the branch was possibly heavier than it has been during most of this summer because of increased available soil moisture which, in turn, allowed an increased rate of tranpiration. The heavy, long branch broke at a weak point during 50 knot SW winds.
We are lucky this did not happen while any of us were up the tree. Shame for the tree, hopefully this does not introduce too much decay into the trunk."
"Cheers Russ, nice update."
Russell pondering on the day of the Open Masters