Summer limb/branch drop

[David Humphries]

Puzzling phenomenon ?

 

An interesting photo study here with this beech

 

I've been driving by (usually within a few hours after each one) when the tree has shed a limb.

 

All in summer, during high temperatures.

 

Bit scary, but a number of people were sitting under the canopy of this one earlier in the day.

 

SLD = The shedding of mature branches in the months of summer.

Usualy horizontal in form (like these three) with a large canopy of leaves end weighting the limbs.

 

Seemingly no specific known cause, although from reading and observing the following are often associated elements.

• heavily end weighted by leaves (and/or mast)

• often windless (although yesterdays was possibly due to increased wind as well as heat)

• noted moisture change in the tree at cell wall structure/fibre level (branches feel dry)

• & often no obvious external signs of defect

 

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[David Humphries]

The first (shots 1 & 2) was in June - 2006

The second (shots 3, 4 & 5) was again in June - 2008

Most recent (shots 6, 7, 8 & 9) was today, July - 2013

 

 

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[David Humphries]

an interesting ISA article from 1983

 

http://joa.isa-arbor.com/request.asp?JournalID=1&ArticleID=1877&Type=2

 

 

 

 

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[Dan Earp]

Interesting, could this be also due to high temps that the fluid etc inside is expanding causing internal weakness ?

[David Humphries]

Yikes! Failures with no symptoms make me twitch when inspecting trees!

 

Have you got a close-up of the fracture?

 

 

Sorry Paul, I posted the thread twice

 

A few more shots attached above, on this version

 

 

 

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[David Humphries]

Interesting, could this be also due to high temps that the fluid etc inside is expanding causing internal weakness ?

 

I think higher temperatures perhaps lead to less internal water?

 

 

 

An interesting comparison to make is between this failure tree (un-mulched) and a neighbouring beech approximately 100 yards away (same soil)

 

Although the first shot here doesn't show the second tree having been mulched, it has been subjected to having mulch placed out to its drip line about three years ago.

 

The mulched beech (which has an amazing array of Ganoderma species at the base and Auricularia mesenterica at the canopy break) hasn't shed a limb during high temperatures.

 

 

Soil hydration perhaps the key here ?

 

 

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[Big Beech]

I recall a few years back, umm perhaps 10 we had some monster oaks drop some monster limbs due to this. was the first time I had heard of summer branch drop or what ever it is called.

these where garden trees, one was far enough away from property but I think it had a kids swing attached and was perhaps 24" wide or so. the other tree shed a HUGE branch that took 3 of us a day to clear, that went through three garden fences and two sheds and that was approx. 36"!!

[treeseer]

Thanks for dredging up the article. Some good guesses on causation re transpiration etc., but every case I've seen, the branch was outside the crown outline and overextended.

 

So it can be chalked up in large part to gravity. (Brilliant huh?) Makes one believe in periodic reduction of sprawling limbs over public spaces; a 5-year cycle perhaps. Especially with previous occurrences. It's easier to prioritize based on probability when one focuses on the single factor of sprawl, but not easy nonetheless. The 1983 management options seem a bit draconian.

[difflock]

I mentioned this a while ago.

Beech, heavily in leaf and v heavily masted.

After a period of intense heat, which likely influenced the leaf/mast growth.

A calm dead still night with v heavy rainfall.

BAM! down it come.

PS a large largely horizontal extended branch, growing towards the South West.

BUT

growing in rank Moss, so dehydration unlikely to be an issue.

Probably the sheer unsustainable weight of leaves and retained rainfall, wind, if there had been any, would have blown most rainfall off I can only presume.

[Paul Cleaver]

ive seen a white pop develop a substantial crack during some very high temperatures a few years ago - i think moisture is a key factor