It's not about the 'healing' of the exterior of your tree but rather what happens on the inside when improper cuts are made.

Attached are some images of what can happen when flush cuts are made. I can send more, too. You might want to hold off on that pruning until you learn more about the long term ramifications of pruning techniques.

Here is a link that might be useful: Click here

There's already a thread on the topic . . .

Here is a link that might be useful: Related thread

Katrina:

Thanks for your report on your own pruning of these oak trees. This is the kind of information we need to get after the publication of Professor O'Hara's article.

But I want to ask a question to make sure I understand correctly--you pruned these branches after the end of the growing season in 2005, and now early in the growing season of 2007 the cut areas have healed over (occluded)completely, meaning that the callus growth--new wood with its own bark--has covered the cut areas?

That seems extrrordinarily fast to me. I know that most oak species can grow callus more rapidly than many other kinds of tree, but I want to make sure I understand clearly.

Although I have no reason not to accept the conclusions of Professor O'Hara's article, I must admit that I would be as uncomfortable as you were making such large cuts when pruning a tree. It will take a while for my old habits and fears to leave me.

--Spruce

Rhizo, I don't read that Katrina, nor Spruce, are advocating making flush cuts, only that cutting into the branch collar a little way is not necessarily the wrong thing to do, and in some, if not many cases, may be the right thing to do. I didn't look at all the photos on your link, but most of the initial ones were showing flush cuts, which seems clearly to have the potential to be very bad for trees.

Resin, I appreciate Katrina's starting a new posting, as this, while relevant to the topic, has little to do with the philosophical argument presently being conducted, except insofar as it bolsters the conclusions of the article. It does give a forum for practical observations, while the philosophical ones can hopefully be continued on the other posting.

Katrina, thanks for sharing your experience - I will utilize it when trimming a maple I have to limb up. A lower branch is about to start rubbing on the porch. I'll try to remember to let you know how it worked next year..., although the branch in question is only about 2-3" in diameter.

I agree that this new thread may be a good place to discuss the more practical applications of the basic principles that are outlined by O'Hara.

dibbit: One of the kinds of pruning cuts that O'Hara discusses is called a "close cut." It is not clear exactly what this means in very specific terms, but my understanding is that with a "close cut" there may be more than a cutting into the branch collar just a little way. I take it to mean that the cut will be "close" in that it will be substantially closer to the trunk than a cut outside the branch collar or one that just goes into the collar just a little way. The difficulty Professor O'Hara has in writing an article like he did is that depending on what your expectations or needs are, the information can seem overly sketchy. But this is unavoidable because as the article emphasizes there are many kinds of trees and different kinds of trees have branch collars that are shaped differently, and they will have different responses to different kinds of cuts, and different susceptibilities to fungal rot entering. So, quite appropriately, he gives just a few examples from prior research to make the point about the stimulation of callus growth by a cut into the collar, but makes no pretense giving a basis for answering all questions about how to prune a specific tree or how close a "close cut" should be.

Also, I need to emphasize that one of the primary concerns of this article is one of high quality wood production. So a "close cut" may be motivated by wanting to reduce the size of the defect core of a tree. But as we see from Katrinas original post here, a "close cut" can also be motivated by aesthetic factors. Sorting out how these two different kinds of concerns may influence the kind of cut we may want to make will take time, and will require the experimenting with many different kinds of trees and different sizes of limbs, etc. I see absolutely endless research projects in all of this.

To sum up, the most important thing I can take away from this article is that there is a good body of solid research that shows a cut into the branch collar stimulates callus growth enough in many if not most cases to more than make up for the larger area to be occluded, even if there is a "close cut" which would substantially enlarge that area.

It is also my understanding that with some trees with branch collars of a certain size and shape, that a "close cut" may at least approximate a flush cut. But I canÂt emphasize enough that the article in no way suggests that there can be any "one size fits all" kind of pruning. No does it support based on prior research any one specific kind of cut for any one kind of tree. Perhaps one or two examples from the research cited could be used to argue for something like that in a specific case, but if so that was not the point of O"HaraÂs citing that research--his purpose was more general.

--Spruce

Rhizo 1, thanks for the link with the photos. doesn't that damage look horrible.

It is true that I did not go so deep into the branch collar for my pruning to be called a flush cut. I think the proof of that is now seen by all but one of the pruning points being cleanly healed.

At the time of pruning, I did not put anything on the cuts. The first year after my pruning I did not see much indicator that they would heal this rapidly. I did not pay attention to how the healing progressed, until a few months ago, when I noticed that two of those trees planted on the west side of my house needed to be pruned again. That is when, I was greatly encouraged to see that even the largest cuts on those two trees were nearly totally healed over with only one or two having maybe the thinest line still needing to finish sealing off.

Then, yesterday, after reading the new findings forestry report, I check those two trees again, and found that after the recent spring growth flush, even the few fine line separations I noticed a few months ago are now closed.

I do not know how our 2005 and 2006 droughts affected the healing process of those two Shumard oak trees. Then again, as far as Oak trees go, my trees are still relatively young. That makes me wonder if their youthful vigor helped the trees heal so quickly.

As for my Scarlet Oak tree, which was 5 or slightly more years younger than my Shumard when they were first planted back in the late '80s or early '90s; it is just as tall as the Shumards. On that Scarlet Oak there was one ugly prune cut we did that would be considered a flush cut. That prune cut now looks nearly as bad as some of the photos in the above link. There is even a little bit of fungus that now can be seen coming out of the northern side of the not yet closed up callous. I suspect the fungus goes further under the callous than can presently be seen. It is a significant concern for me. All the other pruning cuts that were done on the tree were not flush cuts and have currently healed over completely.

Will it be best for me to get an arborist to work on the fungus area in the bad pruning part of the trunk, or is there nothing that will help? Otherwise, is the only solution to cut the tree down now before it grows even larger and will be too expensive to have removed? The damaged area is on the north side of the tree's trunk, and the tree is still trying to close over an about 5 inch wide area with callous. This damaged area along the trunk is also about 9 feet above the ground.

Katrina:

The fact that you are seeing some infection in this old pruning cut is not a good thing. Also, what you are seeing I would guess is a fungal fruiting body, and it is my understanding that these do not develop unless the fungus is well established.

BUT, BUT, BUT, there are many kinds of fungus that can infect pruning cuts, and some of these grow smaller than others and put out fruiting bodies very quickly. So, this infection may not be deep.

Also, fungal infections sometimes develop in old pruning cuts and do not progress into the wood of the trunk of the tree--after the callus closes the wound they die or do not progress any further. O'Hara briefly notes some research findings in his article about this.

I can report one experience I had with a very large and tall tuliptree that was in my yard where I used to live. This was a tree well over 100 feet tall and about 2 1/2 feet in diameter. I noticed a place about 25 feet up where a large old branch had broken off many years before and it had an incomplete covering with callus. Because I was in a neighborhood with houses close together, I was afraid and the risk of huge damage if this tree was blown over or broken with the wind, I did not really trust any arborists opinion--what if he was wrong? People could be killed, a house destroyed. So I had the tree taken down. As it turned out, the tree was still surprisingly sound and did not at that time have a great risk of breaking at that point. That does not say that some problem could have progressed in the future, but the tree was, after all, basically OK.

My recommendation. If you can get up on a ladder and do a close inspection of this yourself (assuming you can do this securely, poke into the area and see what kind of softening of the wood has occurred. If there is a fungal fruiting body that you can collect and put in a jar, do that--it can be identified. And it may not be too late to treat the area with copper fungicide as I have been recommending. If the wood still seems fairly sound--not turned to some kind of soft mass, I would say it may not be too late. And for a first treatment on an area like this I would paint it twice so you get a good "soak in." If the callus later closes the wound the copper fungicide that will at that point be under the callus may have some effect on stopping or reducing the infection.

If you want to hire an arborist that may be a good idea. But I am not sure how much training they have in identifying specific species of fungal rot pathogens, and I am not sure that methods they have to determine the exact extent of a fungal infection. Maybe some arborist can give me some information here in this forum about this. In any case, I would examine the area carefully yourself so you will know exactly what the arborist is talking about and you can decide if it makes sense based on your own observations. And you will know what kinds of questions you can ask.

Anyway, to sum up, I think there is a good chance your tree will be OK.

--Spruce

Wow spruce, Thanks for the helpful advice. As soon as the soil dries some from our current rains, I plan to check the area as you described.

So; am I clear in concluding that according to your remarks I should dig out as much of the fungus as I can access?

If that causes a depression or hole beneath the callous; than I guess, I will need to immediately apply the copper fungicide as you instructed. Would it help to also soak and dry some sawdust with the copper fungicide and then add enough wood glue to bind it for filling any significant hole or depression my digging out the fungus causes under the callous?

Even though you have posted similar advice for others on this forum in the past, you can tell by my last comment that I am pretty novice about such matters. Is there a better way to fill it, if I do end up making a depression or hole beneath the callous?

Also, do local nurseries usually sell copper fungicides? If not, from where do you obtain yours; even better, where could I most likely find some being sold?

Well, I would not try to dig out any rotten wood. What I meant to say is that you should try to look and see if the wood has really significantly softened or rotted. I think the first step is to try to see what has happened. And if you can cut off whatever fungal fruiting body you find up there you could take it to someone and find out what kind it is and then maybe what the extent of its growth inside the tree is likely to be. Perhaps an arborist could identify the fungus, but I don't know what training arborists routinely receive in identifying fungi--there are so many kinds.

I would not, under any circumstances advise putting any significant amount of copper fungicide into a hole or depression in a tree. I can't say that it would always be a bad thing to do, but I have no evidence that it would do much if anything to eliminate an entrenched fungal infection, and it could if it soaked into the sapwood of a tree from the inside of a hole in a tree, do some harm.

The only use I have made of the liquid copper fungicide that I have enough observations of to show me its effectiveness, is as a surface treatment on dead exposed wood after very large pruning cuts or large mechanical injuries to the trunk of a tree. I do have some partial evidence that it can have a toxic effect on the sapwood of a tree if applied in very, large amounts.

If you find, however that in spite of the fungal fruiting body you can see, that the wood seems hard and not significantly rotted or softened, then a surface application of the liquid copper fungicide as I have explained in prior posts, could be a good thing to do.

I would not try to fill the cavity, if removing softened wood or rotted would would create one. I have no experience with this kind of treatment, and I think experience has shown others that cavity fillers do not in the long run help much, if at all.

If the fungus has a head start, then I would not give up--the tree may be able to contain the fungus in the immediate area, and when the callus finishes sealing off the area that fungal infection may die. How you would know that it was dead, I am not sure--perhaps an arborist could in 10 years or so take a core sample to see if the wood in the trunk of the tree below where you new think there may be an infection, is sound. If a core sample is taken, the little hole could be plugged up and there should be no damage to the tree from that.

--Spruce

Great advice!

One thing that can be helpful about the identification of the fruiting body is in understanding just how your particular fungus can be expected to affect your tree. I'd worry much more about some than others.

The best thing you can do for your tree is to make sure that it is properly mulched, watered occasionly if your weather conditions merit it, protected from injury (oops!) and anything that may compromise the root/soil system it which it resides.

Thanks for your further clarifications. Guess my first interpretation was an "over kill" knee jerk reaction.

It is good to know that the copper fungicide is bad for the sapwood area of the tree.

I have put some garden sulfer in the holes I dug for planting some ornamental fruit trees. The idea is that, in the spring rainy season, using the sulfer will help to prevent fungal root rot to set up in these well draining soil need trees.

Is the Copper fungicide much more effective for the air accesible bark situations than garden sulfer would be, if used instead? Not that I now am considering not using the Copper fungicide as instructed. The garden sulfer question, is just to satisfy my curiosity.

I know nothing about any potential benefit from liquid copper fungicide in any soil applications. I would think its activity would be very different from a sulfur product. I would not advise any experiments on your own with this. One thing that strikes me immediately is its potential negative effect on mycorrhizal fungi--the fungi that work in partnership with roots to absorb nutrients.

--Spruce

Katrina, I think you need to put the products on your shelf and keep them there. ;-)

Sulfur can do some wacky thing to your soil pH, too. This can pose problems for your plants as well as the multitude of soil biota so essential to healthy growth and develoment of those plants.

Some of the best ways to avoid root diseases are to foster a viable, healthy soil system, solve drainage issues before planting, and select those plants that are suited to your particular environment (even at the worst of times).

I meant how would putting the sulfer on the fungal infected and unhealed pruning cut work.

rhizo 1, in this part of OK nearly everyone who plants a fruit tree loose their trees to root rot if they do not first de-fungal the soil. Peaches, pears, plums, apples and almonds are the fruit and nut trees, which have locally proved to need such treatment. These species along with pecans, walnuts and some other fruiting and nutting trees have commonly been growing in this part of the state, at least, for nearly a century.

Katrina:

The use of a sulfur fungicide is something I have not tried. One thing is it would have to be a true liquid, and not just a wettable powder. My advice would be if you have a high value tree (to you) you use the liquid copper fungicide I recommend. If you want to do an experiment on some trees and a failure of that experiment on a specific tree would not be a problem, then try the sulfur.

I have about 20 years of experience with the liquid copper fungicide. I have used in situations where destruction of the tree by rot was almost inevitable if left alone. And I have not seen any one time where it has failed (as far as I have been able to observe), even in a few cases where cuts have not occluded after almost 20 years.

But I did try a couple of other things before I tried the liquid copper fungicide and they did not work and the trees suffered. So, experimenting with other things may have a cost.

--Spruce