Questions Concerning Grafting

by Sean

Grafting Knife

Grafting Knife

I would appreciate your expertise in answering some questions concerning grafting. I think that I erroneously believed that if you graft a branch from one type of tree to another type of tree, that the grafted branch would bear the type of fruit of the tree into which it was grafted. Is that ever possible? To be more clear, if you graft a Granny Smith branch into a Braeburn Tree, would the Granny Smith branch bear Braeburn Apples or Granny Smith apples? Could it ever be possible for the Granny Smith branch to bear Braeburn Apples, since it is grafted into the Braeburn tree?

Also, can you graft, say a peach branch, into an apple tree and it bear fruit? If you graft a green olive branch into a black olive tree, will it produce green or black olives? Would that branch always bear green olives, or would it vary over time?

Would the host tree ever be in conflict with the grafted branch? How does the grafted branch over time maintain its own "identity", while receiving nourishment from a different type of tree? I would think that there would be some genetic conflict.

I am just curious as to how grafting works. I hope you are able to take the time to give me some answers.



Hi Sean, you've got a lot of questions! So if I understand your first question, the scion would bear the fruit of that variety - using your example, a Granny Smith scion grafted onto root stock that is Braeburn, that branch will eventually bear Granny Smith fruit.

Although the genetics dictate that the fruit will be of that variety, the rootstock also contributes certain characteristics such as dwarfing of the tree itself. This makes it possible to have really intensive orchards with tiny trees trained onto wires, with full sized fruit.

For your second question, no. You can't graft a branch off a peach onto an apple. They are just too far removed genetically. If you graft any kind of apple onto another apple or crabapple, that will work, and in some cases, peaches can be grafted onto other stone fruits (cherry, plum or nectarine) successfully.

Green olives are actually just immature or less ripened black olives to my knowledge, so that's not a good example.

There have been cases of conflicts between different grafted trees - I've seen really old trees with what you would think are completely compatible grafts, but a windstorm took off the branch completely and cleanly, as though it really hadn't been grafted at all. It's a mystery how the graft managed to live so long, and actually get to a good size before the graft failed.

There isn't so much of a genetic incompatibility, but in some cases a virus or bacterial infection can be passed along.

Hope that helps with your understanding of grafting and how it works.

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