I have a large oak tree, approx.forty feet tall and sixty feet wide. The main trunk is about six feet in diameter. At about the ten foot height it splits into five large (18"dia.) branches,at this point there is a cavity between two of the branches.
(If you held your hand up, with your fingers pointed up as if trying to fit it into a small hole, your arm being the main trunk and your fingers the branches the cavity would be like at your palm.) This cavity fills with debris and recently I noticed a small tree growing in there. I removed the tree and cleaned out the roots and debris. The space atarts the size of a large punch bowl,it continues down about 18 inches where it becomes as narrow as a mail slot, this is as far as I could reach. I found no apparent damage to the bark.
I am worried that this cavity can develop rot from water and debris collecting in there, or insects or other pests making a home.
Should I be concerned?
I would like to fill in the cavity and create a dome so that water and debris run off.
Is there a product for this sort of application?
I thought of possibly insulation foam, the type that expands to fill in gaps, or a wood filler, concrete?
What would you suggest?

Thank you for your time.
fv

Hi
I'm in England. I would not be overly concerned with the water collecting in the crevices of the tree and I would not recommend that any type of filler is used and definitely no attempt to drain the liquid.I would agree though that it is likely a good idea to prevent other trees growing in the cavity by pulling them out (although it could produce a very interesting view, here in England we sometimes get large Hollies growing out of Oak cavities).I would suggest a more holistic approach. Keeping the tree in good health by preventing compaction of the roots,removing weed competition and providing an organic mulch. That said it would be worth checking the limb/branch attachment points for obvious defects and extensive decay that may lead to failure. If this were to be a concern it could light remedial pruning might be the answer.
I am iterested in what capacity you view this tree?

quote:

posted Tuesday March 29, 2005 03:42 PM
Hi
I'm in England. I would not be overly concerned with the water collecting in the crevices of the tree and I would not recommend that any type of filler is used and definitely no attempt to drain the liquid.I would agree though that it is likely a good idea to prevent other trees growing in the cavity by pulling them out (although it could produce a very interesting view, here in England we sometimes get large Hollies growing out of Oak cavities).I would suggest a more holistic approach. Keeping the tree in good health by preventing compaction of the roots,removing weed competition and providing an organic mulch. That said it would be worth checking the limb/branch attachment points for obvious defects and extensive decay that may lead to failure. If this were to be a concern it could light remedial pruning might be the answer.
I am iterested in what capacity you view this tree?

Thank you for your comments.
I love the tree, it is the centerpiece of my front yard. My concern is with the roots of the "parasite tree" growing into and possibly damaging the oak, or wildlife moving into the crevice.
By the way I am in South Florida (hurricane country) so I worry about any weakening of the branches which are over the house.
Rather than a filler, how about some kind of an umbrella or cover to divert matter from collecting?
Thank you again,
fv

I am not familiar with the plants that grow in Florida. In the main a plant that has green (or possibly red) leaves is photosynthesising and therefore producing its own food, making it an endophyte i.e. just residing on the host plant. Some plants are hemi-parasites that tap into the water conducting wood of a tree with a root-like structure called a haustorium, but not the sap containing the sugars and with all other factors normal this puts very little strain on the tree. That is not to say that a large endophytic plant could not cause problems. The thickening of the roots could cause problems to the structure of the tree, a poorly rooted specimen could be blown out of the tree and there is a possibility that the new tree could be extracting nutrients from the decaying heart of the tree that would have been exploited with adventitious roots of the tree itself.
It is unlikely that any structure erected to prevent debris and water from entering the crevice would be of benefit, but if you were to do so make sure that it does not cause damage to the tree (i.e. rope, nails, etc.). The tree is not defenceless and trees have been dealing with these things for alot longer than we have been around. A defence of healthy wood to fungal attack is the water content that prevents oxygen which the fungus needs to survive and also various phenolic compounds that are toxic to invaders.Drying the crevice could be detrimental. As for the critters they will not likely to do much harm and they need a home too (if they are foreign invaders that upset your ecosystem shoot them).
All this said if you have parts of the tree that if they failed could cause harm or unacceptable damage (which I could not diagnose from a few thousand miles away) you really need to have the tree inspected by a competent professional Arborist. The only advice I can be sure of is that if that wind starts 'a' blowin, don't stand under your tree.

FV, the problem here is the safety of the tree. A large cavity at a strategic point like the main crotch may be cause for concern.

Don’t just guess at this. Get some expert help. The American Society of Consulting Arborists website has a directory for consulting arborists around the US. Contact one in your area and have the tree checked out. A tree of that size can cause a lot of damage. Hopefully, there will be some treatment, rather than removal of the entire tree.