Ginkgo Rootstock Suckers and growth of tree. (rather long)

arktrees(6b NW Arkansas)June 24, 2013

Greetings plant people,
I have a question for the forum readers that have experience with grafted Ginkgo. And I would like some opinions as well. I will be cross posting this in the "Tree" and "Conifer" forums.

In spring 2007 we planted a Princeton Sentry Ginkgo in a location where the more narrow habit of this cultivar was appropriate near our drive way. It has been in it's present location for 6 years. Overall the tree is healthy, heavily foliaged (for a Ginkgo), has generated caliper, produces male flowering parts in the spring, etc. From this you would think all is well.... not exactly.

So does those of you with grafted Ginkgo have suckers from the rootstock every year. We have had this tree planted for 6 years, and every year it produces new suckers from the rootstock. At this point I would expect that this tree was grafted probable 10 years ago. Also since the graft is so much larger, I would expect apical dominance to have reduced rootstock sucking to nil by this time. But that is apparently not the case with this tree. So the question I have for you is, do your rootstocks on your grafted trees continually attempt to sucker?

Which brings me to my next point about this tree. Apical dominance, or more correctly, the apparent lack thereof. Being the cultivar Princeton Sentry, the tree should have upward ascending branches, and new branches/growth should follow this pattern. In this trees case....... not so much. To begin with I had to stake it for about 3 years before it could stand on it's own against the elements.... until this year. This year the tree is basically flopping over to one side again. But that's not the most unexpected thing. Few of the branches grow upward, some even grow downward, and many are basically pendulous. In fact the tree has gotten much wider, but barely taller than when planted. Hardly the growth pattern one would expect from Princeton Sentry. For that matter growth has been less than expected even for Ginkgo. In comparison I see local seed grown Ginkgo growing 2'+/yr with none of the other issues.

The above leads me to the following open ended thoughts. I am aware that for most Ginkgo, scions taken from branches tend to want to continue growing as branches. One of the advantages of PS was that apical dominance was would reassert itself in these grafts, and a central leader would then form. This is not happening, at least not strongly with our tree. Other characteristics fit PS. The leaves are large, thick, and typically lacking lobbing as us typical of PS. Fall coloration is late, and in line with other local Ginkgo that I believe to be PS. Plus I have seen reference to PS being late to color. The tree flowers male in the spring as one would expect. Since the tree is relatively small, that would support that it is the graft flowering, therefore no graft loss.

All of this make me wonder what could be happening. The rootstock sprouting makes me wonder if there is not some amount of graft incompatibility, thereby reducing growth as whole, producing suckers, and who knows what else.

Another thought I have had is the perhaps there has been a mutation in the original scion that greatly reduced the apical dominance. This could potentially result in lack of suppression of suckers, lack up upward branching, failure to maintain a leader, pendulous growth, weak structure so that the tree is now on the "floppy side again". Kinda a reversion PLUS.

Lastly, it could be wrongly labeled cultivar. I tend to discount this since the other characters fit PS.

At this point, I am less than enamored with this tree. Vigor is lacking, growth form is lacking, and we have gotten fall coloration exactly one time. then I see two seed grown trees sitting in burlap, on top of the ground, showing vigor with aggressive root growth though the burlap, and 1.5' long shoots, after being dug last fall, and missing most of their root mass.

I would appreciate any thoughts as to what may be happening.

Thank you for you time,

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hortster(6a, southcentral KS)

Hey, Arktrees,

I also thought of graft incompatibility when you mentioned the suckering, kind of like the roots want to pump out carbohydrates and the top isn't using enough.

Thinking of taking cuttings for grafting, I wonder if the chance grafting of pendulous ginkgo twigs, taken from scion after pendulous scion might result in a broader or even weeping form, even if repeatedly taken from a series of originally fastigiate Princeton Sentries.

From your description, though, it sounds more like mislabeling.

We had both seedling and grafted ginkgoes at the nursery, some of which were in the ground for 7 or 8+ years. I don't remember suckers showing up on them in that field, not to say it couldn't be more common. Never happened on the tree in my yard, either (Autumn Gold).

Since the rootstock on your tree was taken from a seedling it may be female. Keep choppin' 'em.


    Bookmark   June 24, 2013 at 5:15PM
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arktrees(6b NW Arkansas)

Thanks hort, I really appreciate the feedback. If it is incompatibility, then the graft seems likely to eventually fail. I had a matte over around the base, with mulch on top to cut off all light to the rootstock hoping that would curtail suckering...... NOPE! Pulled it up yesterday, and there is a full ring around the base of pale white suckers from the RS looking for a way out to the light. I'm seriously considering allowing one of them to grow at this point and taking my chances on getting a female tree. Even if it turns out to be female, other than my two dwarfs, there are NO other Ginkgo ANYWHERE near, so pollination would not be likely. If I did this, I could leave the current graft in place and keep my female significant other counterpart happy, while something more satisfying came up. I know she likes it even though I'm not so happy. I also thought about trying to find a place for another one.

On a side note, do you have an opinion as to which cultivar develops yellow fall color the earliest? I'm subject to early and late freezes in my location, and I'm thinking that an earlier turning selection (if I replace this one) might be a wise consideration.

Thanks in advance,

    Bookmark   June 25, 2013 at 11:39AM
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hortster(6a, southcentral KS)

Sorry, never have studied timing of ginkgo fall coloration. Is this tree in a fertilized and watered lawn area? Good conditions might be pushing it past normal abscission?

That ring of suckers is weird. Methinks the tree is trying to tell you something...


    Bookmark   June 25, 2013 at 11:55AM
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joeschmoe80(6 (Ohio))

Slightly OT, but mentioned by Arktrees...the fall coloration of ginkgos around here is unreliable. Some years we get a gorgeous yellow, other years it's more yellow-green or they freeze off. They, in general don't turn until after Nov. 10 or so.

Is that typical in your area, Arktrees?

    Bookmark   June 25, 2013 at 12:32PM
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arktrees(6b NW Arkansas)

Thanks hort. Knew is was a shot in the dark. Our tree is in water fertilized lawn. I learned several years ago to not fertilize past early July or it appears to interferes with fall color on most everything. However, moisture could still easily be a factor, since we are rarely too dry in the fall. But in a local park, three trees I believe to be PS, typically change color late in the fall season. I agree that something is up with the tree. The question is what? I'm thinking safe (i.e. new tree/letting a sucker grow), instead of investing more years to only have it fail. Thanks again for your input.

Ginkgo seem to vary here. There are some that are early on the University of Arkansas campus.Others a couple blocks away is a park nearby, in a small valley (hence should be cooler) change well into November after those on the campus at a higher elevation are done. Our own PS developed yellow once in 2009 around the time you indicate. Each time it seemed on the way to developing color, were on pace for November when cold weather would stop the show.


    Bookmark   June 25, 2013 at 2:10PM
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