F
Frans
Guest
If that were true, then the branch collar would have tears. In Sudden Limb Drop, the collar is cleanly sheared.
If that were true, then the branch collar would have tears. In Sudden Limb Drop, the collar is cleanly sheared.
sotc
Dormant hero!!
correct me if im wrong but i always thought sudden limb drop was associated with shear water weight. hot afternoon, wide open stomata, pumping serious amounts of water through the tree and over loading limbs.
sotc
Dormant hero!!
never experienced that
F
Frans
Guest
http://www.treebuzz.com/forum/showflat.php?Cat=&Number=6084&page=0&view=collapsed&sb=7&o=&fpart=1
CA. tree failure report Program:
http://groups.ucanr.org/treefail/index.cfm
What is the major cause of limb shear in trees?
There is no single cause. Limb shear occurs because of a combination of different factors. These include environmental conditions, the age of the tree and species variation. The variation may be within species as well as between different species. You can see a whole paddock of River Red Gums and 48 out of the 50 will be fine and two of them will have fallen limbs all round them. Certainly some species of trees are particularly prone to limb shear.
However the majority of cases are caused by some defect in the union between the limb and the trunk, or some section of the limb adjacent to the trunk. Very often we can see evidence of decay. This may have been caused by something as simple as a cockatoo or possum eating away at the bark, allowing decay to set in. Or perhaps the tree has been subject to environmental limitations, such as drought or compaction, and its ability to repel decay may have been reduced. Sometimes the reasons may go back 10 or 15 years. For example, people forget that 10 years ago, a new water main was put in and half the tree’s roots were severed. Trees are amazing survivors but such things take their toll. Limb shear may be the consequence of actions from years ago.
Having said all that there are still occasions when arborists can find no explanation at all for why limbs fail.
Which species are most vulnerable to limb shear?
Some eucalypts are particularly vulnerable. River Red Gum (Eucalyptus camaldulensis) (see top right), Narrow-leafed Peppermint (E. nicholii), Sugar Gum (E. cladocalyx), Lemon-scented Gum (Corymbia citriodora), Spotted Gum (Corymbia maculata) and Swamp Mahogany (Eucalyptus botryoides) are trees to be watched in particular. Most species of Elm are also prone to limb shear. Ulmus procera and U. x hollandica seem equally likely to do it.
The problem with Swamp Mahogany in the urban situation may go right back to the original genetic stock used for propagation, or the lack of care taken in the nursery to remove problem branches. The problem seems to stem from the morphology of the tree. Because of a condition called "included bark", the branches are typically not very well attached to the tree.
I think it’s important to understand that the eucalypts in the urban situation are quite different to the eucalypts in the forest. Eucalypts in the forest tend to grow straight up as they compete with each other for light. In the urban situation, the trees have more light and consequently, a more extensive canopy and branch structure.
We are currently engaged in research to test the hypothesis that shading of lower branches, or over pruning of branches, may have an influence on their tendency to drop.
What can be done to minimise the danger?
I think it is important to realise it is difficult to predict when a limb will fall. However there are steps that can be taken that will minimise the risk. As trees age, the likelihood of limb shear increases. Old or vulnerable trees should be examined regularly by a professional arborist who needs to climb the tree and examine the limbs closely. Some limbs may need to be removed, or it may be that the whole tree needs removing. Where a limb is aesthetically important, cabling and bracing can be employed, so that if the limb does fail, it will be less likely cause an injury.
About Leigh Stone: Leigh Stone is a full-time arborist, a part time lecturer at Burnley College and is completing his Masters thesis on "Sudden Limb Failure in Trees".
CA. tree failure report Program:
http://groups.ucanr.org/treefail/index.cfm
What is the major cause of limb shear in trees?
There is no single cause. Limb shear occurs because of a combination of different factors. These include environmental conditions, the age of the tree and species variation. The variation may be within species as well as between different species. You can see a whole paddock of River Red Gums and 48 out of the 50 will be fine and two of them will have fallen limbs all round them. Certainly some species of trees are particularly prone to limb shear.
However the majority of cases are caused by some defect in the union between the limb and the trunk, or some section of the limb adjacent to the trunk. Very often we can see evidence of decay. This may have been caused by something as simple as a cockatoo or possum eating away at the bark, allowing decay to set in. Or perhaps the tree has been subject to environmental limitations, such as drought or compaction, and its ability to repel decay may have been reduced. Sometimes the reasons may go back 10 or 15 years. For example, people forget that 10 years ago, a new water main was put in and half the tree’s roots were severed. Trees are amazing survivors but such things take their toll. Limb shear may be the consequence of actions from years ago.
Having said all that there are still occasions when arborists can find no explanation at all for why limbs fail.
Which species are most vulnerable to limb shear?
Some eucalypts are particularly vulnerable. River Red Gum (Eucalyptus camaldulensis) (see top right), Narrow-leafed Peppermint (E. nicholii), Sugar Gum (E. cladocalyx), Lemon-scented Gum (Corymbia citriodora), Spotted Gum (Corymbia maculata) and Swamp Mahogany (Eucalyptus botryoides) are trees to be watched in particular. Most species of Elm are also prone to limb shear. Ulmus procera and U. x hollandica seem equally likely to do it.
The problem with Swamp Mahogany in the urban situation may go right back to the original genetic stock used for propagation, or the lack of care taken in the nursery to remove problem branches. The problem seems to stem from the morphology of the tree. Because of a condition called "included bark", the branches are typically not very well attached to the tree.
I think it’s important to understand that the eucalypts in the urban situation are quite different to the eucalypts in the forest. Eucalypts in the forest tend to grow straight up as they compete with each other for light. In the urban situation, the trees have more light and consequently, a more extensive canopy and branch structure.
We are currently engaged in research to test the hypothesis that shading of lower branches, or over pruning of branches, may have an influence on their tendency to drop.
What can be done to minimise the danger?
I think it is important to realise it is difficult to predict when a limb will fall. However there are steps that can be taken that will minimise the risk. As trees age, the likelihood of limb shear increases. Old or vulnerable trees should be examined regularly by a professional arborist who needs to climb the tree and examine the limbs closely. Some limbs may need to be removed, or it may be that the whole tree needs removing. Where a limb is aesthetically important, cabling and bracing can be employed, so that if the limb does fail, it will be less likely cause an injury.
About Leigh Stone: Leigh Stone is a full-time arborist, a part time lecturer at Burnley College and is completing his Masters thesis on "Sudden Limb Failure in Trees".
sotc
Dormant hero!!
interesting, but she danced around the main topic.
F
Frans
Guest
Yes, she did. Also the TB posts do not mention in Sudden Limb Drop, the branch collar being sheared off cleanly. Almost like the branch is yanked off the trunk straight out, or cut off with a saw. No peeling.
Bodean
Cali dreamer
I've seen a few euc sudden limb drops, never tear always a fracture
and drop.
Like a drop cut.
rarely anything lays down and remains attached or tears bark.
Maybe not enough water to continue the bond from cell to cell.
and drop.
Like a drop cut.
rarely anything lays down and remains attached or tears bark.
Maybe not enough water to continue the bond from cell to cell.
M
Mike Maas
Guest
I've never seen Sudden Limb Drop, but I've seen a lot of limbs drop. There's always been a structural issue to start.
That leaves me doubting it even exists. If it does, it's very rare or non-existent in my area.
That leaves me doubting it even exists. If it does, it's very rare or non-existent in my area.
F
Frans
Guest
Their are lots of things I have never seen, but that doesn't mean I doubt it exists
treesandsurf
Treehouser
What about the water necessary for the production of carbohydrates in photosynthesis that is supplied by the roots. The energy which the leaves are creating is a result of several factors, one of the most important being the H20 that is supplied by the underground portion of the tree. jp
sawinredneck
Treehouser
I think? I have seen the sudden limb drop phenomenon on the Elm trees in KS. With our hard clay soil and little rain in the hot months, you will go around and pick up branches off the Elms. No wind damage, a very nicely formed and healed collar, but the heartwood is rotten, and broken off behind the collar, inside the trunk if you will.
Does this sound right?
Does this sound right?
R
RIVERRAT
Guest
Yes Andy that sounds right. Your description agrees with mine & Mikes thoughts.
I have seen the limbs of ash trees the Green Ash in paticular drop limbs. But in every case I have seen there has been decay or some factor that clearly caused it. Dont know that this is "Sudden Limb Drop" or not. I dont believe that title describes what I have seen.
I have seen the limbs of ash trees the Green Ash in paticular drop limbs. But in every case I have seen there has been decay or some factor that clearly caused it. Dont know that this is "Sudden Limb Drop" or not. I dont believe that title describes what I have seen.
X
xtremetrees
Guest
- Thread Starter Thread Starter
- #63
Hey River Rat good to read ya.
R
RIVERRAT
Guest
Why thank you dude!
"She" is a he... Leigh.
sotc
Dormant hero!!
ooopsie
M
Mike Maas
Guest
jp
True, but the roots and stems are like straws. The leaves do the sucking. If the root system is weakened by low sugars, the branches that die first are out at the tips, typically near the top of the tree.
My point is that the branch live or dies on it's own. The tree doesn't control the branch, the branch controls the tree.
Understanding my poorly expressed point here will help you understand more about pruning a tree. I see many arborists with the idea that they are controlling growth factors by pruning, when in fact, they are just cutting off branches.
A common mistaken idea, is guys that cut lower limbs to give more strength to the top of the tree. Total hogwash. Another, is cutting off adventitious growth to stop it from "sucking" the strength from the tree.
X
xtremetrees
Guest
- Thread Starter Thread Starter
- #68
MasterBlaster
Administrator Emeritus
Dogleg!
M
Mike Maas
Guest
What does a bent tree have to do with Compartmentalization?
MasterBlaster
Administrator Emeritus
I was wondering that myself then I considered the poster...
W
Will
Guest
I just got through reading this thread and real nice, lively discussions. I like this.
As far as Sudden Limb Drop, I think this is someone's trying to coin a phrase; something we all have a tendency towards. It is very difficult to accept the fact that sometimes there is more than one right answer for different situations that may appear very similar.
Limbs of different species of trees with different structure and growth patterns, with and without defects, may experience what I prefer is the earlier term of Summer Branch Drop. I have seen this alot on hot, humid days throughout the summer. This is often associated with a defect, but not always. Sometimes the separation is clean and sometimes not. This seems to be species specific. Not dissimilar to storm damage.
Dave
As far as Sudden Limb Drop, I think this is someone's trying to coin a phrase; something we all have a tendency towards. It is very difficult to accept the fact that sometimes there is more than one right answer for different situations that may appear very similar.
Limbs of different species of trees with different structure and growth patterns, with and without defects, may experience what I prefer is the earlier term of Summer Branch Drop. I have seen this alot on hot, humid days throughout the summer. This is often associated with a defect, but not always. Sometimes the separation is clean and sometimes not. This seems to be species specific. Not dissimilar to storm damage.
Dave
M
Mr. Sir
Guest
That seems to happen a lot on our Florida Elms and Laurel oaks.
SkwerI
Treehouser
My theory/ observations on the laurel oaks dropping limbs is this:
We typically have a very dry period in the spring (April/ May) where we may go 3-4 weeks without rain. Temps are rising and can get into the low-mid 90s. The extended dry, hot weather weakens the trees and the wood contracts and can crack. Then we get a big, long rainstorm that drops an inch or two of rain over several hours. The trees soak up the water and the wood swells. 1-2 days later we have dozens of calls for broken limbs and split trees.
We typically have a very dry period in the spring (April/ May) where we may go 3-4 weeks without rain. Temps are rising and can get into the low-mid 90s. The extended dry, hot weather weakens the trees and the wood contracts and can crack. Then we get a big, long rainstorm that drops an inch or two of rain over several hours. The trees soak up the water and the wood swells. 1-2 days later we have dozens of calls for broken limbs and split trees.
