Big ‘Little Gem’ vine maple (Acer circinatum)

[Cruiser]

“Experience is the name we give to our mistakes.” Oscar Wilde

The air layer failed. By late April emerging shoots stopped extending. By mid May they had all dried out.




I’m not certain why it failed.
A few potential theories..

1) there was a heat wave a few weeks after the layer was started. 90+ degrees F. Very hot for this area and early in the growing season.

2) Too much water around the girdle. A large plastic disc was placed at the girdle to promote lateral root growth. It did not drain well. The disc + frequent waterings to address the higher than normal temps could’ve created issues?

3) When creating the layer I strongly scraped the girdle to ensure all cambium was removed. Multiple times. Could I have scraped too deep?

4) The sphagnum/soil/bark was contaminated.

Does anyone have feedback? Ideas as to what could've gone wrong?

 

[Hack Yeah!]

Bummer, maybe sawing off the bottom roots didn't help? I doubt 2 3 or 4 would have caused the failure. Maybe it wasn't as healthy as it appeared when you got it?

 

[0soyoung]

Three things are necessary to grow roots. Oxygen (air), carbohydrate, and auxin.

My guess is that there was adequate air in the substrate/soil. That is, I don't think you piled on so much loose bark as to suffocate the roots.

The girdle, however, interrupts the flow of auxin and carbohydrates from above.

• Carbohydrates are stored in the vacuoles of every living cell as starch grains and will be converted back to sugars that can be metabolized. When they are exhausted, however, that is it for the roots.
• If there is no node below the girdle, the only source of auxin is what is left in the phloem supporting the PAT stream. Just like the rooting process, a high auxin level is required to up regulate cells for them to morph into root tips that generate even more auxin (that is used locally) as a root tip. Simply reducing the auxin flow into the tip below a critical level will down-regulate the root tip tissues and it quits growing. When it was growing epidermal cells a few millimeters behind the tip become the hair roots (microscopic extensions of dell walls) that load the bulk of water and minerals.

My guess is the loss of auxin stopped the necessary root growth. But it is also possible that the cambium below the girdle died and, in the process, commanded living cells in the wood to extend their teloses to clog up the xylem, shutting off the water flow. If so, you should find punky/gooey bark at the bottom of the girdle and correspondingly a discoloration in the wood going extending upward from that level.

Maples have very low phloem pressures in winter as evidenced by their tendency for winter die-back. So it might have been better to have waited until the first flush had hardened to cut the girdle. Then the phloem pressure would have been pumped up and there would have been more auxin in the pipeline to keep the roots going quite a bit longer. All you need to do confirm/refute this idea is find another and try again a bit later in the season next year

 

[Cruiser]

My guess is the loss of auxin stopped the necessary root growth. But it is also possible that the cambium below the girdle died and, in the process, commanded living cells in the wood to extend their teloses to clog up the xylem, shutting off the water flow. If so, you should find punky/gooey bark at the bottom of the girdle and correspondingly a discoloration in the wood going extending upward from that level.

Maples have very low phloem pressures in winter as evidenced by their tendency for winter die-back. So it might have been better to have waited until the first flush had hardened to cut the girdle. Then the phloem pressure would have been pumped up and there would have been more auxin in the pipeline to keep the roots going quite a bit longer. All you need to do confirm/refute this idea is find another and try again a bit later in the season next year

Thanks. The girdle was made directly against the graft bulge so it’s possible there was no node below it.
There also discoloration in the girdle, like you would see with branch dieback. I’ll check for goo…

 

[andrewiles]

That's a bummer. Sorry to hear that.

Little gem will layer nicely, so don't give up.

I'll second the advice against messing with the roots at the same time you completely sever the phloem. Though that shouldn't cause this...

I'm surprised it died so quickly. It does feel like a catastropic disruption of the water flow upward.

I had a nursery Rainy Day vine maple, which is basically the same as Little Gem, up and die on me for no obvious reason. I had layered a big branch off the previous season. It leafed out, then completely and quickly collapsed. When I looked at the roots there had been no new root growth that spring and there was obvious decay. So either during the winter, or early spring, the roots had completely failed. And the top then followed. Just one data point but I wonder if these dwarf vine maples are fincky in some way. My separated Little Gem and Rainy Day air layers are all very happy -- no issues so far.

 

[Cruiser]

But it is also possible that the cambium below the girdle died and, in the process, commanded living cells in the wood to extend their teloses to clog up the xylem, shutting off the water flow. If so, you should find punky/gooey bark at the bottom of the girdle and correspondingly a discoloration in the wood going extending upward from that level.

An autopsy revealed no goo. The tree has been dead since mid May though, so it could have dried up.
Discoloration does appear to extend upward from the base. Is that what you were talking about?

 

[Cruiser]

That's a bummer. Sorry to hear that.

Little gem will layer nicely, so don't give up.

I'll second the advice against messing with the roots at the same time you completely sever the phloem. Though that shouldn't cause this...

I'm surprised it died so quickly. It does feel like a catastropic disruption of the water flow upward.

I had a nursery Rainy Day vine maple, which is basically the same as Little Gem, up and die on me for no obvious reason. I had layered a big branch off the previous season. It leafed out, then completely and quickly collapsed. When I looked at the roots there had been no new root growth that spring and there was obvious decay. So either during the winter, or early spring, the roots had completely failed. And the top then followed. Just one data point but I wonder if these dwarf vine maples are fincky in some way. My separated Little Gem and Rainy Day air layers are all very happy -- no issues so far.

I may get a few more trees like this last one.

For next time, I’m considering styling first. Then going with the tourniquet method of layering.
One of the issues I ran into with this last maple was too many branches getting in the way of the work that had to be done.

 

[0soyoung]

Discoloration does appear to extend upward from the base. Is that what you were talking about?

The discoloration I was referring to would only be seen by splitting the trunk or making a series of cross-cuts to expose the wood that should have been carrying water. It is checking for the stain of compartmentalization which should be a bit redder color at this time. The idea is what I showed with an air layer failure of mins several years ago.

Maple airlayer turning brown

Hi team, around the start of spring (September 15th) I began my first ever airlayer. My Sangu Kaku is a multi leader and a great opportunity for multiple projects. Contrary to my own doubts it has managed to spout roots and leafed out amazingly. Everything was going great, I noticed so solid...

www.bonsainut.com

 

[19Mateo83]

I think the root work did it in and how early you applied the layer. I generally try to wait till the first leaves have hardened off and I’ll apply a light fertilizer to increase vigor before I layer. Maples are funny like that sometimes though, one will throw roots if you look at it wrong and another will just up and die. Consider it lessons learned. It was a nice tree. RIP little buddy.

 

[Cruiser]

With nothing left to lose, the dead tree presents additional learning opportunities…

Styling practice. And a chance to see how my vision for it could have played out.




The vision.




Salt in the wound, for sure, but it’s good to know what could’ve been.

 

[Hack Yeah!]

I wonder how well they heal scars? Super nice structure

 

[Cruiser]

Thanks. Not sure about little gem. The standard and wild vine maples around here don’t heal particularly fast or slow. An average rate, I suppose.
@andrewiles thoughts?

 

[andrewiles]

I'm not sure. I doubt it's fast.