I watched the video, couldn't help but wonder about this guy's knowledge of how plants work.
Wound callus tissue does not transfer nutrients. The rolling wounds are useless to the tree, other than to compartmentalize injury by the wire:
It is not until much later that regular cambium tissue overgrows the callus tissue--possibly decades...If you're too aggressive with this kind of thing, you will kill your tree.
A week or so ago debate insued over callus tissue and it's ability to transfer nutrients or not. Some said no, I said yes. I said I had some pictures to share and now I can relate what I have and maybe more discussion can move along.
Mark's quote above suggests that rolling callus tissue is a poor conductor of nutrients due to the nature of callus tissue which for all intents and purposes is actually akin to cancer via growth cells out of control. My contention is that callus tissue is a defence mechanisim for a tree damaged and in a state of shock. While I agree that a callus is a poor conductor of nutrients my contention is that nutrient travel does not take place in the callus tissue but much deeper at the cambium which knits almost within days of damage. The callus tissue is a bandage of sorts to protect the vital life line below that needs protection from damage or else the tree dies. This tissue is much like the tissue that evolves around burn victums where by thick blubbery scar tissue develops to protect the baby like new skin where real vital fluid exchange takes place. Many of my clients have suffered burns in house fires and during reconstruction many times a healed wound will begin bleeding at the slightest touch. This could be curtains for a tree.
I showed these pictures to Ted Matson whom I think we can all agree is a very noteable bonsai master around the nation. During our exchange he verified indeed that damage to trunks and branches will take place at the cambilum level in only thousand's of an inch cell tissue to maintain life and fluid/nutrient exchange, while scar tissue (callus) is only a topical bandage.
The Central Valley of California, Bread Basket to the World is full of agriculture. One of my current homes under reconstruction is a Japanese family whose home burned down a few months back. He was a farmer for 62 years. Mostly stone fruits and grapes. I asked him about grafting, and callus tissue.
This was his story and how it realates to bonsai.
Making money in the food growing businesss is very complicated. Many times a farmer will plant a crop that is making money one year only to have it fall out of market the next year. In the case of stone fruits many years of growing to achieve adult crop producing trees may take many years. If a certain fruit begins to decline financially, what can a farmer do? Change to a better stone fruit. How can you invest ten years in growing trees only to pull them out to plant new ones then waste another ten years to get back to where you were?
You don't plant new trees, you graft on a better financially sound tree. In the case of this farmer, he related that when peach trees are planted a farmer can have his choice of grafting on literally any peach, any nectarine or any plum to the peach stump. If a farmer starts with plum as a stump then he can only graft on a new plum or apricot but no peach or nectarine.
So peach is the way to go....
In this first picture we can see peach stumps with new stone fruits grafted on. A large sacrifice leader is left on the stump to keep it alive while the new scions knit. (Just so you know I have already spent most of January and all of February learning his grafting skills and he has said that when he finds his old knives he will give them to me. They are his Fathers from Japan and they are close to 175 years old. I can hardly wait).
In the fourth picture we can see that the grafts have already taken and callus tissue is starting to grow. This callus tissue is growing nearly five taimes faster than the tissue at the cambium intersection at the point of conception for lack of a better term. The nutrient path was the first thing the tree made. in the case of the callus tissue it serves two purposes, one to protect this tender bond, and two to lay down the necessary wood to maintain the bond. At this point wind will tear these off in a heart beat. I know, they lay all around the orchard as testiment to their weakness at this point.