Grafting to fill in spruce

[ATH]

I worked with a client who has a spruce tree that is a little bare on one side because there used to be another tree shading it. It is too sparse to expect it will fill in on its own - the bare spot covers about 1/4 to 1/3 of the bottom 3' of the trunk. He asked if I thought we could graft branches from other parts of the tree onto the trunk to help fill that it. The trunk is about 8" dbh. What do you think...can we successfully use a bark graft to get new limbs filling that part of the tree back in (I am thinking no more than 1/4" to 1/2" diameter scion)?

I have never grafted anything before...but willing to learn! It would probably be in good shape if we could get 3-4 grafts to take...but that is the big IF that I just don't know.

Thanks.

 

[TheJollyLogger]

It should be doable, though no guarantee. Spruce actually do a pretty good job of filling in bare spot

 

[imagineero]

This question comes up from time to time and nobody ever tries it. I'd be curious to see the outcome, but my guess would be probably not.

This image shows how a branch penetrates into the heart of the tree, but look at the shape the tree takes around the branch in order to support it.

The above diagram illustrates a branch where it penetrates the stem. Each vertical growth ring of the tree is interlaced with a horizontal growth ring from the branch, with a 'tail' from the branches growth ring extending out mostly downwards creating the 'bulge' shown in the first image. There's a much better illustration of this which is shown in many books but I can't find it. It shows very clearly years of interlaced rings between a branch and a stem.

Grafted branches are starting life on the back foot, and when it comes right down to it they have no real structural integrity. They're just suckers. You could graft branches on, but basically for it to have any sort of hope of not breaking off the branch is going to have to be as close to vertical as possible. I'd be curious to see it done anyhow!

Shaun

 

[ATH]

Good point on the integrity of the branch even if it does attach.

I talked to a guy who does a lot of hardwood grafting today. He wasn't sure about spruce, but he did offer some thoughts (with doubt that it will work):
1) It is best to graft young wood to young wood...so getting the graft to take on the trunk is going to be difficult.
2) Grafting to a limb would be better, but they need to be vigorous. The only limbs even close to the area are not looking real good, so I don't think that is an option. I did wonder after the fact if giving the tree a shot of N this fall might help stimulate better growth/more likely to graft???
3) He thought that the best chance might be to graft a bud rather than a small limb.
4) Pointed out that a really good grafter gets 70-80% success with ideal root stock and scion...in a green house. Does not bode well for the chances here. Certainly not a good option for my first attempt. I'd love to try, but I don't want to leave wounds on the side of his tree just so I can play!

 

[treeseer]

Pics would help...

Maybe if you are able to find dormant buds you can scrape the bark off them to encourage release?

 

[CanopyGorilla]

Good point on the integrity of the branch even if it does attach.

1) It is best to graft young wood to young wood...so getting the graft to take on the trunk is going to be difficult.

Yup...... I can't see this working with a spruce of this age. Even 8"dba is MUCH older than most successful root stock or branch grafts in a controlled greenhouse environment. The side that is bare due to phototropism will most likely fill itself in with time. Maybe not quite as quickly as desired, but as someone already mentioned spruce are fairly good at this.