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Leaving understock on young graft

Posted by maple_grove 6 (My Page) on
Tue, Nov 27, 12 at 10:09

Well, I'd like to continue this discussion that was briefly entertained on another current thread. I'm interested in learning more about leaving the understock on a young graft to promote the health of the new graft. It was recommended for the case of young Pinus contorta 'Chief Joseph' that plant health and overall performance during at least the young years is drastically improved if a single branch from the understock is maintained

It's well known that leaving the understock on is beneficial for miniature and gold-colored scions, since these types of scions will produce a limited amount of photosynthate. The reason is obvious, the understock leaves will produce food for the roots and thereby contribute to the well-being of the entire plant.

Now, I have also heard that in certain cases, the rootstock is left on and even if it has no foliage, that it will still be beneficial to the plant's health and it is about this that I'm curious. To me it is surprising that a little understock stem has so much carbs stored that it can feed the plant from it's reserves, for years. Since this came up (in the other thread) I would like to learn more. Which plants might be good candidates for this sort of treatment, and why would you do this rather than leave on a full branch with leaves (one which is not shading the scion of course)? Why would you "remove the understock gradually" rather than leave a branch on until no longer needed and cut it off all at once?

Thanks, and please jump in with any other questions you have on the topic :0)

Alex


Follow-Up Postings:

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RE: Leaving understock on young graft

  • Posted by whaas 5a SE WI (NW) (My Page) on
    Tue, Nov 27, 12 at 11:00






I don't get that either. You're just forcing the plant to bleed and heal a wound twice, plus you have a larger wound at the graft location if you leave the stub on.

One example is a Pinus mugo 'Sherwood Compact' that I got. It was about 5 years old and had a fatty stump left on it and in return left a large leaking wound once removed. Perhaps folks are talking about cutting back gradually in year 1 and 2?

Sure there is a logical explanation from the experts.




This post was edited by whaas on Tue, Nov 27, 12 at 16:58


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RE: Leaving understock on young graft

No knowledge to add here unfortunately but I just wanted to add this off-subject comment in the other thread, so...

Alex I loved the new bed-hill! I'd love to see pictures as you fill it up with plants over the next months. Please keep us posted!

Back to subject now...

Fotis


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RE: Leaving understock on young graft

i had once speculated .. key word there..

that peeps who send them thru the mail.. leave them there.. in case the package gets turned over in shipping ... otherwise.. i have seen plants with multiple bamboo stakes for what i presumed was the same reason ... shipping security ...

otherwise.. i reduce the number of buds on the upper understock ... so a few new needles are produced.. the first year... and then late that summer.. take off all the buds ... and then usually forget about it for a few years ... as the needles normally age and fall off ...

go ahead.. you may begin the mocking of the theory..

ken


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RE: Leaving understock on young graft

if the scion is super mini/or such a tiny scion I leave a few branches on while the plant takes root either in the pot or, in the ground. I have several grafts here I planted 2 and 3 years ago that are so small you'd think I'm nuts to have planted them, however, they will live if you water them and give the understock the chance to root. over the course of each year I cut off more of the understock but I make sure there's enough to live as a seedling until the scion is big enough to live as the new host. it's kind of a game of speculation but experience does help. for me, once a scion has made it to the size of a golfball, I'll probably clip off the understock, however if a golf ball piece was grafted of super mini foliage, then I'll wait a few years to help it establish in a pot or, in the ground.

Dax


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RE: Leaving understock on young graft

Thanks Dax. If I understand correctly, your comments are in line with Brent's (and in line with common sense), in that some foliage is necessary for this to help. Unfortunately, I don't remember where I got this (bad?) information from that even without green tissue, an understock stem can continue to provide food and promote survival. Could be I'm misremembering something here.

Ken, I like your theory that some nurseries leave the understock on to protect young plants during shipping. Though sometimes I see the opposite - I feel some nurseries that sell fresh grafts remove the understock shoot system prematurely for purely aesthetic reasons and to provide what looks like a finished product, though it may not in the best interests of the plant.

Fotis, my friend, thanks and will do.

Alex


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RE: Leaving understock on young graft

You can leave a branch on a graft w/no buds so long as the branch has needles. It'll live for a few years.

Dax


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RE: Leaving understock on young graft

Alex-

Re: "Now, I have also heard that in certain cases, the rootstock is left on and even if it has no foliage, that it will still be beneficial to the plant's health and it is about this that I'm curious."

-I have never heard this. A shoot without foliage eliminates photosynthesis and nutrient cycling, thereby cancelling root/shoot growth benefits.
-A stub might be better in many instances rather than a near-flush-cut wound depending on the plant's ability to heal and the site of CODIT (Compartmentalization of Decay in Trees). If the understock is similar diameter to the graft, or larger, the ability of the remaining understock to heal the wound following complete removal of the understock could be limited and could invite additional infection or decay. As such, if you remove the understock to a stub 1-2" above the graft union, then allow the grafted plant to develop larger, then remove the stub completely after the grafted plant is 2x or more the diameter of the stub, it will more completely heal and cover the graft union.

"Which plants might be good candidates for this sort of treatment, and why would you do this rather than leave on a full branch with leaves (one which is not shading the scion of course)? Why would you "remove the understock gradually" rather than leave a branch on until no longer needed and cut it off all at once?"

-The more understock foliage you maintain, the larger the understock diameter will be. You don't want a massive diameter, because when you ultimately remove it, you want the wound to heal quickly. By removing the understock gradually on graft-sensitive varieties, you still maintain the beneficial root-shoot interactions, but keep the caliper of the understock minimized.
-Good candidates for this have been mentioned above: true miniatures, many golden or variegated varieties.
-Timing related to removal of the understock: this depends on growing conditions, health of the plant overall, etc. Dax's advice on when you can remove understock for a miniature is good, I might upgrade from a "golf ball" size to a "tennis ball" size. For golden/sensitive varieties, it depends on health, growth rate, sun/shade, etc.

-Brent


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RE: Leaving understock on young graft

If the understock is similar diameter to the graft, or larger, the ability of the remaining understock to heal the wound following complete removal of the understock could be limited and could invite additional infection or decay. As such, if you remove the understock to a stub 1-2" above the graft union, then allow the grafted plant to develop larger, then remove the stub completely after the grafted plant is 2x or more the diameter of the stub,

==>>> in 'dad' talk.. lol

if the boo boo is bigger than the babe.. he will just pick at it.. and it will never heal properly ... lol

in tree talk.. whats the hurry ... it might live 20 to 100 years.. get a life.. and let it grow up.. ... as always with trees .. you can ALWAYS do it later ... [but you cant glue the scion back on.. when your micro surgery fails] .. and perhaps that is part of it ... some stuff is just to tiny .. for common hand pruners.. and if that is your quandary .. why not do it next year ... and tied into that is the angle of the dangle.. and how the scion is attached to the understock.. sometimes you just cant get the pruners in there safely ....

not helpful ... ????? ...lol

ken


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