Aerial roots to hide reverse taper

[treebeard55]

I did a little demonstration this morning for the Fort Wayne Bonsai Club. Many here are probably familiar with this technique already, but some may find this post of interest.

The tree is a Ficus salicaria, willow-leaf fig. When I bought it there were three major branches originating from the same point on the trunk, which resulted in a bulge (orange arrow.) I took off one of the branches, but the bulge has slowly gotten worse.

To try to correct the reverse taper, I decided to try to induce aerial roots in the area of the trunk shown by the yellow bracket. If all goes well, I'll later bind the aerial roots to the trunk until they fuse to it. This will result in both more visual interest in that area, and more visual bulk as well.

I first poked a bunch of little wounds in the bark with the points of a leaf-cutter. Then I put a loose sleeve of .4-mil polyethylene sheeting around the trunk, and filled it with long-fiber sphagnum. I used latex gloves when handling the sphag; sporotricosis is rare, but not impossible. A couple of strips of ordinary packaging tape closed up the plastic "envelope."

Polyethylene sheeting, unlike some other plastics, will pass oxygen and carbon dioxide while holding in water vapor; this per research done by the late Dr. J. R. Cody of Texas. (Some of you will recognize the name.) That makes it good for air-layers and projects like this one. I bought it at a local paint store that sells it for drop cloth.

When I got home, I put a loose shield of aluminum foil around the upper half of the sphagnum ball, to darken the interior more and make root formation more likely.

If all goes well, I'll be able to post a progress report this summer.

 

[woodguy]

So no rooting hormone? Seems like a solid plan to improve this tree. Looking forward to the update.

 

[treebeard55]

No, no rooting hormone. I know from experience that this species throws aerial roots easily; this tree itself demonstrates that. So I didn't feel it was necessary.

With something else that's less prone to throw aerial roots in the first place, I would have used it.

 

[Kirk]

You could also take several smaller saplings, run them up the side of the existing tree, bind them and allow them to fuse. That would correct the reverse taper and beef up the trunk. The tops of the saplings could then be used as future branches.

Kirk

 

[Si Nguyen]

I like what Kirk said. Whenever you trim the branches on top, just stick the cut branches into the soil around the tree, then after they rooted, just wrap them closer and fuse them to the trunk. You would need a warm climate or a green house for this to work though. My cuttings usually take about 2-3 months to roots. I had use them for making fake aerial roots to fuse to branches. You could also use the rooted cuttings as new side branches for that bare trunk too. Your tree needs some low branches. Or, you can air-layer the 3 top branches off to use in a forest later, and work with a smaller shohin tree for the remaining bottom part. The bulge/reverse taper where the 3 big branches come off will only get bigger. That's hard to hide!
Good luck with it!
Si

 

[treebeard55]

Kirk and Si, that would have worked too. I chose this way, partly because I think the technique is that our Ft. Wayne people will be more likely to use, once they understand it.

An early update. The tree did lose some foliage, due to a brief-and-unintended exposure to winter winds when the plastic bag shielding it came loose! But it's busy replacing those. And so far four new aerials have grown out far enough to be visible thru the polyethylene. Yea!