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Successful grafts that stay dormant?

Posted by jbclem z9b Topanga, Ca (My Page) on
Thu, Oct 11, 12 at 17:45

Over the last three years my pome fruit grafting has been pretty successful in the sense of grafts taking. But I've noticed some grafts that grow a bit the first year, but then seem to go dormant and stop leafing out or even growing new shoots. If I scratch their bark surface I can see bright green beneath, so I know they are still alive.

Is there any trick to get the buds to come alive? I've thought of trying gibberellic acid but can't find any information about it's use this way, or at what strength it would be used.

John


Follow-Up Postings:

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RE: Successful grafts that stay dormant?

John:

You have to force them to grow. That means good growing conditions and most importantly cut off everything else on the tree. Or at least cut back enough that the tree is short on leaves. It's about the balance between tops and roots. If the plant has way more roots than tops it will grow more top. But it will want to grow that new top where the plumbing is biggest. Think of the limbs as water pipes. Growth will be strongest where the pipes are biggest.

It's hard to force growth on an old tree unless you cut the top way way back.


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RE: Successful grafts that stay dormant?

  • Posted by jbclem z9b Topanga, Ca (My Page) on
    Fri, Oct 12, 12 at 6:08

I should have mentioned that none of my grafts are on young rootstocks used just for grafting purposes. Some are on older trees in the ground, some are on recently bought trees in pots. But in all cases I'm adding grafts to trees where I want to preserve the original tree's fruiting ability. So a drastic pruning back would be counter-productive.

Some of these grafts are on a 20-25 year old Satsuma plum tree (which needs pollinator varieties), so it's age could explain the sluggishness of some of it's grafts. But the same old tree has no problem sending out suckers each year that keep growing until I cut them back...I've even grafted onto some of these suckers, and that might turn out to be the preferred way on old trees that I don't want to cut back a lot.

But some of the other dormant grafts are on young containered apple trees that also have other grafts that have acted normally, sending out shoots. So it's not making much sense.

Next spring I think I'll experiment with some gibberellic acid that I have (and have never used). We'll see if that awakens some of these dormant grafts.


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RE: Successful grafts that stay dormant?

Sorry to say, but I think fruitnut is right, at least regarding your older trees. You really need to remove roughly 1/3 of all wood on an old tree in order to get vigorous enough growth from your new grafts.

On your young trees, however, I think there is a simple solution. Next spring just as the buds are beginning to swell on the tree, cut a notch in the bark about 1/2 inch above any branches/grafts that you would like to grow out more. This diverts the flow of sap and sends more energy from the roots into your grafts instead of the rest of the tree. The concept is basically to notch the bark in such a way that sap can flow up from the roots to your grafts, but gets blocked from going much farther. This usually works and I have done it with much success on my own grafts and other branches that needed a little extra push because they started out too small.


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RE: Successful grafts that stay dormant?

Or wait, no, I think I got that a little wrong.... notching prevents auxin from reaching your graft. Auxin is a chemical produced in the growing tips of branches that flows down the tree and keeps buds from branching out too much. For example, when the tips of branches are removed, the auxin factory is removed, so the remaining buds will not be prevented from growing, thus producing a more bushy branch that does not grow solely from the tip of the branch. In similar fashion, when you cut a notch into the trunk of a tree right above a branch, auxin from the top of the tree that flows downwards is blocked from getting into that branch, thus promoting more growth of that branch.

That's what I meant to say. On an older tree, you could still try notching, a.k.a. ringing or girdling. However, I am not sure how successful it might be since the branches are pretty darn thick. You'd have to remove a good bit of bark above a branch to prevent a lot of auxin from reaching it.


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RE: Successful grafts that stay dormant?

John:

Any fruiting tree can be pruned back 50% with little loss in production the next year. But on a 25 year old tree even 50% doesn't mean your grafts will grow especially if they've set there dormant a while. Cutting back more than 50% will force growth somewhere but most will be right next to the biggest cuts.

On a new potted tree you might have to cut off enough to delay fruiting a year on the original. Even doing that won't force everything.


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RE: Successful grafts that stay dormant?

My plan is to cut off the entire branch above the graft.


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RE: Successful grafts that stay dormant?

  • Posted by jbclem z9b Topanga, Ca (My Page) on
    Fri, Oct 12, 12 at 22:15

Notching sounds like it might work for me, focusing the solution on an individual branch. How wide would I make a notch (the width of the branch, 2x the width of the branch, 1/2 the width of the branch??). Also, how deep? Does the notch heal in a few years, allowing the different flows to resume through the healed area? And if I have 2-3 more months of warmish weather, would it be worth trying right now. I'm in S. Calif, but up in a canyon and the weather is usually warmer during daytime, and cooler at night than the nearby city(L.A.).

Can you use notching on a branch coming off of a branch...you would be blocking off horizontal flow, does that still work, does auxin flow in the upper part of a horizontal branch?

John


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RE: Successful grafts that stay dormant?

Good questions. I am by no means an expert in notching or how auxin works as I've only tried it about a dozen times on my young trees; however, I have indeed successfully applied these principles to my advantage in many/most cases.

Based on what I have learned, auxin travels mainly in the bark of the tree, produced by all growing tips of branches, and flowing downwards as if pulled down by gravity. So to inhibit the flow of auxin and thus encourage growth of young buds or branches, you only need to cut into the outer bark in a location that will prevent it from flowing into such buds/branches. All I have ever done is used a sharp knife to make small cuts through the bark, roughly 1/2 inch above buds/branches, taking care not to cut deeply into the heart wood. While notching with the knife has not been 100% effective for my trees, it has been maybe 50/50 or a little better, which has been good enough for me. The advantage that I see of only using a sharp knife and making very small, narrow, shallow cuts is that they stop or slow the auxin for only a few months as the wounds heal very quickly. However, most sources I have seen do recommend using a saw to not just cut the bark but actually to remove a notch of bark, the same thickness as the saw blade (1/16 to 1/8 inch or whatever it may be). Again, you need not remove the wood any deeper than the bark, or else the wound will take longer to heal. Obviously using a saw would have greater effect than just a knife, and would take longer to heal. So it depends what you want. The knife does work in my experience. You can also make the cuts two or three times during the season to keep the auxin out if the vigor still isn't there for you. But overall I would guess that using a saw blade will result in more vigor and higher success rate.

Sunlight is also a factor. If there is too much shading to the buds, then all the notching in the world won't really get the buds to grow vigorously because sunlight really kicks growth into gear. Just something to be aware of -- if you can do your grafting or notching on a sunny part of the tree, so much better the success rate.

In the mild, relatively warm climate of Southern California, I would think notching could be done with some level of success at any time of year; however, assuming your branches aren't growing much during the winter months then it might not really pay now as the notches may heal prior to the main growing season which I guess would be in March/April-ish. For obvious reasons, you want to promote the growth while the tree is in growth mode! So I would still do the notching in the spring timeframe, same as I do here (actually more like May here in WI).

I have done notching with success along horizontal branches in addition to notching on the trunk of the tree. You may need to perform the notching in two places -- one notch on the trunk to stop/slow the flow of auxin from the main trunk, and one to stop/slow auxin traveling in towards the trunk from the tip(s) of the branch(es) where your bud is located that you want to grow. For a graft, the second part is not really applicable if you have no real growing tip developed yet, or don't want to notch your graft or cut off your growing tip! But if you ever had a bud on the existing tree that you wanted to grow and branch out, then you can certainly apply the auxin flow principles to promote its growth.

I might be all wet, but I truly do hope that these ideas help someone out there in some way. And if anyone out there knows better how auxin works, please, be my guest and chime in!

I do have videos on YouTube that show a little of what I have done with notching on my young Honeycrisp tree. It does work. See link below.

Here is a link that might be useful: Scoring, Ringing, Girdling, or Notching to Inhibit or Promote Tree Branch Growth


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RE: Successful grafts that stay dormant?

I think the advice given here is all very good. The most rapid growing grafts are always on most vigorous trees and notching will not invigorate a graft much if shoots on top of the tree are not growing with good vigor.

Older pomes usually have a lot of spur wood and trees with a lot of this are likely to grow much more slowly. Removing substantial amounts of this kind of wood (small knobby pieces that carry fruit) tends to invigorate trees. A photo would go a long ways towards allowing clear diagnosis here.

Of course, with most any pruning, the more radical it is the more the vigorous will be remaining shoots(if you don't kill the tree, which is unlikely with pomes) but it is the fruiting wood that slows a tree down and removing hole branches without heading remaining branches back or drastically reducing their spur wood with fine cuts often fails to increase vigor. Instead you may just wind up with improved fruit.

I use notching with some success but I think your first concern should be pumping up the vigor. Nitrogen and ample water are also important as are all issues of plant nutrition. Pests like root nematodes and borers can slow trees. I suspect the soil may be excessively alkaline in parts of Topanga, although when I was raised there, starting about 49 years ago, I didn't know what pH was. Still, I had no trouble getting trees to grow with great vigor- I used loose alfalfa hay for mulch, which was free for the hauling from the feed store at the base of the canyon.


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