Last fall we did some digging on one side of this green Japanese maple, so I was concerned that we may have injured the roots when it leafed out this spring and the leaves looked burned. I cut back all branches that looked dead (disinfected between cuts), and hoped it would survive. A friend stopped by recently and pointed out the issues on the trunk also and sent me to this forum. I don't see any insects in the injured bark or in the leaves. Any suggestions would be greatly appreciated. I've attached pictures of the leaves, bark, and tree after pruning. This is my first post. Maura
I had a similar problem 2 years ago, on a potted laceleaf maple, and also on a palmatum palmatum planted in the garden. On both, it was on the south side of the tree, the most exposed to the sun: temperature shock? (cold nights and very sunny days) Have a look at this thread, maybe it can help you: Healing bark damage
I would use a sharp knife or box cutter (some of the smaller ones, with tighter machined tolerances offer better control than the old fashioned bulky cutters). Carefully cut along the outer edge of the wound, removing about 1/2" all the way around the wound. You should find green cambium layer exposed along your new cut, when its back to the healthy bark. If you are still into brown and dead bark, cut another 1/2" until you are cutting along the healthy bark, exposing the green cambium layer (this is important, it's the green layer that the wound wood will form to cover over the exposed damage). It's important that it is a clean cut and not a tearing cut. If the cambium layer is damaged it will not form wound wood. Also note that it is very important to sanitize between cuts with a 10:1 (water to bleach), or with 70% or higher rubbing alcohol, or Lysol spray, or hand sanitizer. Next, I recommend sealing the cut with Elmer's wood glue, bonsai cut paste, or my last choice is tree sealer (only because I don't like the looks of it, but it does come highly recommended by someone I have great respect for on this forum and their lifetime of experience can't be discounted) If you go the route of Elmer's wood glue, you can cover it with heavy duty aluminum foil. Use the dull non stick side against the glue (the glue will bond to it, but it will still lift away as the wound wood forms underneath. Here is another tip, before applying the glue, take the piece of foil and press it against the wound area. This will make an impression or mold of the wound area. Use scissors to cut it out for a very nice fit. Apply glue to the area and press the nicely formed foil in place to seal and protect the wound. I always make sure the glue seals along the top, but I leave a very little space along the bottom to allow water to drain, in the very unlikely case that water does get into the wound. I find it's best to start from the bottom working upward, so that any excess glue is pushed out the top and can be neatly cleaned away with your finger. Then you can wrap it with Dewitt tree wrap (because it breathes, unlike paper wraps; and it stretches a little too for a very nice fit) If you use tree sealer, then you may want to wait for it to dry before wrapping. If foil is used, it can be wrapped immediately after. Consider using 0-10-10 in the coming weeks to help prepare the tree for winter and I also find it helps speed up the formation of wound wood to speed up the recovery time. (I feel less is more when using fertilizer, sometimes I use half the recommended dose, just to play it safe) Also consider not using nitrogen fertilizer too late in the season, usually anything after late spring is too late in my opinion (in my area I don't use it at all). It's been found that too much late season growth fueled by nitrogen or excessive moisture can contribute to splitting bark in the following early spring. Hope this helps and good luck!
One other tip, consider using Dewitt tree wrap this fall to protect the tree trunk from winter sun. Sometimes bark damage can occur on the SE side of the tree, due to sharp temperature swings from sun warming by day and freezing at night. The wrap will help protect or insulate the trunk from these sharp swings in temperature over winter and early Spring. If a rodent caused the damage it will help keep them from snacking on your tree bark when food supplies are limited over winter.
We are in an area of very high rainfall (160 - 200" per year), so might the tree wrap keep too much moisture in the wound area? I've never used it, and I'm not sure if it's available in our area, but I could order it online. Maura
I only use that wrap on my maples because it breathes and can easily dry out after rain and melting snow. I try to stop about an inch or two from the ground to prevent it from wicking up moisture from the mulch and soil.
Here in high rainfall Normandie, anything like wraps that interferes with airflow is contraindicated. With respect to any kind of wound sealant, there are still a few people who recommend it, but most wisdom is let the air dry out the wound post surgery. That's what I do, and it works very well. I would be concerned, in a high moisture environment, of creating a situation where moisture might seep in and fester.
And after letting the air dry it out, how many years does it take for the prevailing wisdom method to close a 1.5" wound? Sure, no wound is always perfect once it closes; but I think it's pretty good for one year (please see the picture below). There was a time, several years back, that I used the method of prevailing wisdom and it would take a few years to close a 1.5" wound; when my un-popular method takes 1 year to do the same. I find much of the prevailing wisdom comes from experience with other faster growing and much larger varieties of trees. It's hard to find someone with a Ph.D writing specifically about Japanese maples. It's also hard to find a study that does not have a hidden agenda like economic or to promote a specific product in todays world of Science meets the bottom line fueled by currency. Some are just written to dis-prove a common practice or a so called myth. They make for good reading, but are they practical for a slow growing Japanese maple? Theory vs. results (my picture); at the end of the day results speak louder than theory in my mind.
Plants are like children, they all grow at different rates. Not to mention if we feed them to make offensive linemen! :) (Not referring to the 0-0-10 of course). Anyway, some vigorously growing plants heal up very rapidly, I suppose in around the same time. You're not suggesting the Elmers stimulates the growth? Although I would think the exigencies of modern capitalism would promote the use of various sealers rather than the contrary, we're not going to thresh out the pros and cons of this here. My point was simply that, over time, views have evolved. presumably because gardeners have gotten better results. Not trying to change your mind, just pointing out the alternatives to the OP. I have a large (by some standards) garden in a soggy area, and do a lot of pruning (sometimes major); I used to use sealer, now I don't, and I think I see better results without. (Always difficult to judge because as I said, different individuals respond differently to surgery. But in general my results now are very good.)
I agree that what works for you is great. I am certain in the past, your method of sealing was different than mine. Since you do lots of pruning, you should give my method a chance and prove me wrong. Next opportunity you have to remove two branches of similar diameter on the same tree, use your method on one, and mine on the other. Next chance I have, I will do the same and document the process and results. Below are some pictures of the items needed, and pictures of my process as described in my post above. I am not promoting Elmer's fuels growth or anything like that as I would sound like a snake oil salesman of yesterday. I believe that when you let the cambium layer dry out it is a set back in the process of closing the wound. Harsh summer and winter winds can also cause a further set back in my mind. With my method, the wound wood forms faster, because it is protected from this set back (Elmer's and foil). Many times, with the dry out method, wound wood is slow to form and the growth rate of the trunk consumes the cut faster than the wound wood can close it. Or in then end, it's a close tie and that is why most cuts need to be further from the trunk. (I am not promoting removing the collar, but with my method you can get closer for a less noticeable end result once closed. A common problem I see is that the wound wood is slow to form, then once it get's it's start it is slowed down or goes stagnant. Another thing to consider, since you are in an area of high rain fall and you are concerned about moisture getting into the cut, my method keeps the water out. What I meant, is that an economic study saying you should not seal, may prove beneficial to an arborist who has to take the additional time and resources to seal. To the arborist, the cost of time and money spent on materials outweighs the benefit (mainly to the business). Then someone who is a hobbyist, plant collector, or home gardener reads it and thinks sealing is bad. Take the time is money component out (if you are doing it for a hobby you should have time, if not maybe consider collecting ornamental grasses instead of Japanese maples, which is a labor of love for many, but certainly not the right choice for anyone pressed for time). With cost of materials vs. benefit, again for the arborist, a tube of Elmer's and a roll of foil will go fast; but for the average hobbyist, plant collector, or home gardener the roll and tube will last several seasons. So if the cut closes faster and looks nicer, the benefit outweighs the cost to me. I guess it's my opinion not to take an economic study for face value. You need to consider the target audience.
Staying on topic, here are pictures of bark damage from squirrels that closed within a year using my method. On the Sango Kaku, one wound was almost half way around the trunk and the other was well over 3/4, both were several inches long(4" on one and 8" long on the other). The squirrels actually used my Sango Kaku as a scratching post, literally shredding the bark. Quite devastating to say the least! No leaf damage or loss of branches/trunks despite the massive damage. Yes it makes me so mad that it happened. But if those two branches/ trunks failed, I would have lost 50% of the tree's canopy, in my garden (with tours etc.) the tree would have to be replaced. Both are on the top side of the branch/ trunk. I am sure if I just let it dry I would have had leaf loss in the middle of the summer (at best) and then if I let the rain settle into the wound, I would have lost the branch / trunk totally on the largest of the two. With 75% of the bark around the trunk being removed, leaving a bottom sliver to support an immense amount of the canopy's mass, this was destine to fail without using my technique. ("my technique" meaning the technique I use and recently this year I have discovered others use foil too, I am not claiming credit for the invention of this application, I guess people have been using foil long before I walked the earth in both horticulture and bonsai circles) The Filigree closed in one growing season, keeping in mind it happened late spring. The Orange dream had two wounds, one was pretty major at the base near the root flare and another smaller wound further up the trunk (both are present in the photo). They both closed in less than one year. I encourage others to try it, I think the results speak for themselves. If not, then good luck and I will keep Practicing horticulture Differently :-)
