Years ago, my brother lived in a house with a beautiful ash tree in the front yard. Whether by design, or luck, it was in the perfect location to allow the canopy to not grow where it would cause roof problems, and the branches were in the perfect 33 degree separation to allow the maximum amount of growth. Usually, such efforts are in fruit orchards, or the pecan orchards we have locally. The maximum amount of yield is achieved from a tree with that shape.
After a few years, my brother noticed the tree was losing leaves, and the usual lush canopy was becoming more bare by the day. As luck would have it, a close neighbor was having a tree trimmed by a professional, which allowed him to walk over to speak with the arborist.
The arborist walked over to examine the tree, and told my brother what was wrong. He added if my brother knew someone familiar with concrete, he could explain what to do and save him some money. He explained the procedure, my brother called me, and I volunteered to help.
The fork in the tree was holding water. This allowed rot, the tree was being damaged, and would eventually die. Our job was to remove the water, remove the rot, and place concrete in the void. The concrete needed to be shaped to allow drainage, and if done correctly, the tree would more than likely survive.
The fork was about 7 feet above the ground, which required a small step ladder. Climbing up the ladder revealed the problem, and we went to work.
First we bailed the water, then we took a wood chisel to the rot to remove the damage. We took turns and eventually had nothing but healthy wood exposed. At this point, the void in the fork was substantial, and I begin figuring how many bags of concrete we needed. I figured two to be safe, and we started the next phase of the project.
I started mixing the concrete, while my brother sprayed all the exposed wood with pruning spray. I slowly added water to reach the perfect amount between dry-packing and flowable. I'd poured enough curbs to know the point.
With concrete, you have a lot of options. Dry packing, which is where it can be packed into a voids, which allows repairs on walls, although you usually have to only place enough to fill most of the void and leave a shallow void for filling with a wet material, such as grout. I needed the point where the concrete was dry enough to work, but wouldn't slump when worked; just like for curbs.
I achieved what I wanted, my brother handed it up to me as I filled the void, and I eventually had the patch shaped like the contours of the branches. It was the right shape, but I didn't like the way it looked. I asked my brother to hand me the pruning spray, I sprayed it on the fresh concrete, and used a water brush to make the pattern of the trunk. The spray made the concrete a brown, which closely resembled the color of the tree.
Over the next month, the tree started making new leaves, it eventually filled back out, and as far as I could see, it was healed. The patch could be seen, if you looked closely, but to a casual observer, it would be unnoticeable. I felt we accomplished our task, and saved the tree.
My brother eventually divorced, his wife received the house, and I didn't go back to her house until years later. The tree was gone. I don't know what happened, and I refused to ask. I didn't want to know if our effort was in vain, and even worse: I didn't want to know if it was a whim to have a yard easier to maintain.