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graft union orientation

Posted by Michael Phillips 
graft union orientation
January 22, 2019 01:33AM
All sorts of theories abound about graft union orientation at planting. Bud unions can be positioned so as to have the prevailing wind "push" the varietal shoot towards the rootstock. Of course that's totally irrelevant when a nor'easter blows strong from the other side. I think this is less of a consideration for the stronger whip-and-tongue union. What would be more helpful (maybe) is knowing the tree's orientation in the nursery, so "south" is south once again. And then there are those who say the dominant lateral root should point towards the magnetic pole, provided there is a dominant lateral. Myself, I plant a free-standing tree so available roots radiate around as fully as possible. I know one guy who planted his trees at a significant lean to accommodate strong winds across the plains . . . and those trees hardly righted, making this the biggest stretch of all. There can be value in facing the bud union towards the stake with semi-dwarf trees, but now the question becomes which side the stake?

Graft union soliloquies might best be left to Shakespeare . . . but why not have at it on this cold winter's night?

Lost Nation Orchard
Zone 4b in New Hampshire

Edited 1 time(s). Last edit at 01/22/2019 04:22AM by Michael Phillips.
Re: graft union orientation
January 26, 2019 06:56PM
I've always felt that with budded trees that the scion portion of the GU needs to be on the side of the prevailing winds. In this case, it the wind will push the scion into the GU as opposed to being pushed away from it, potentially causing stress and forcing the GU open and breaking it partially or wholly.

For whip and tongue, the same approach applies just differently. The "V" should be situated perpendicularly to the direction of prevailing winds. If the V is situated parallel to prevailing winds, strong winds could push the scion through the union (breaking in part of whole) since there is nothing to push against, less structural stability.

Any additional support such as staking or trellis can increase the strength/stability of the tree until its gets fully situated. Tilting your tress so they lean into the wind can provide some support, but it is not as good an alternative as staking. In all cases, once the tree is structurally strong (after a few years) the GUO doesn't really matter. If you're in a situation where your trees' GUO isn't ideal, then providing some sort of ancillary support can get the tree over the hump, allowing the GU to strengthen in time, and ultimately making a strong tree. Actually, I encourage some type of support in all cases for at least a few years. This could be a stake, a trellis, or something else, but it will no doubt only make your situation better. In fact, researchers have shown that in all cases, support not only makes a stronger tree, but also increases precocity and long-term productivity by reducing the "wallowing effect" caused by winds. So even if the winds don't break your tree, they can have a significant effect on the health and establishment of the rhizosphere. And we all know that what happens below determines what happens above!!

Lastly, none of this makes any difference if your trees weren't properly grafted or budded. So make sure you have healthy rootstock, scion wood, and effective propagation technique. You can't make a bad tree better, but you can make a good tree stronger.

Now, what say you?!

Mike Biltonen, Know Your Roots
Zone 5b in New York

Edited 1 time(s). Last edit at 01/26/2019 10:15PM by Michael Phillips.
Re: graft union orientation
January 26, 2019 07:13PM
Mike, my knowledge of graft union orientation follows what you've laid out exactly: "the scion portion of the GU needs to be on the side of the prevailing winds", and "The "V" should be situated perpendicularly to the direction of prevailing winds". And I'm a big fan of staking for initial establishment, just as you've suggested.

I truly value the passion and wisdom represented in this forum!

Door Creek Orchard
Zone 5a in Wisconsin

Edited 1 time(s). Last edit at 01/26/2019 10:16PM by Michael Phillips.
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