Last May I started an air layer on an old Japanese maple (see “Air layering a Japanese maple“). Curious if there was any root growth, I opened up the bag in February. There was callus, but no new roots.
Good callus, no roots
To stimulate the production of new roots, I opened up the callus and applied root hormone. I then replaced the moss and waited for spring.
After removing a strip of callus
The maple leafed out as it always does, but a few weeks ago I noticed that the leaves above the layer line began to turn pale. This is a good sign as discoloration is common when new roots start to develop.
Pale foliage at the apex
To satisfy my curiosity, I opened up the bag and looked inside. A few new roots were just getting started.
I replaced the moss again and closed up the bag. I’ll watch the bag carefully this summer to make sure it doesn’t dry out and will see about adding soil around the moss if it starts to dry out too quickly. I’ll peek inside again this fall.
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Good luck Jonas. I did a similar procedure with a Trident Maple last year and was able to cut the layer off early this spring, when leaf out came it acted quite normally. Only problem I saw when I potted it was that the roots had developed on one side of the tree and not on the other. I am hoping that it is correcting that by it’s self right now. Next spring I’ll find out and if it is still one sided I’ll try to cut the callus as you did to see if I can induce it to root all round.
Ryan Nichols says
Great post Jonas! I learned something new today! Do you know why the leaves turn pale? My best guess would be a shift in nitrogen and energy allocation. Nitrogen being the most likely nutrient requirement since its one of the most mobile ions in the plant and its essential in protein synthesis along with many other important processes that necessary for cellular development.
Jonas Dupuich says
Good question Ryan – I was hoping _you’d_ have the answer! My guess has always been that disrupting the phloem decreases the circulation upstream which prevents the affected area from getting adequate nutrients, but I don’t have insight into which nutrients – or whatever else may be causing this – are deficient enough to cause yellowing. It would be interesting to figure this one out – thanks for bringing it up.
Scott Roxburgh says
Another great post Jonas.
Has the scar on the base of that Maple healed any this year?
Jonas Dupuich says
Thanks Scott – as for the maple, yes, it appears to be healing nicely, but has a long way to go yet. I’d have to really let it run for a couple of years to close it up faster – maybe I’ll do this in a year or two depending on how the layer and grafting go.