Hi,
I often read that air is supposed to prune the roots of our trees.
Well, this ufti (unknown from the Italian) does not know about that.
Of course there is a trick to that. For rodent protection, that tree is in a pot with bottom removed.
So the roots should escape under; but I guess that they had decided to go over the rim.

The blue thing is a tie, but the brown ones are roots ... When is air supposed to prune them ?
Funny that those roots explored the dirt by passing over the rim. I had expected the roots to hit the pot and sink .
This tree has two trunks (the one to the left is in fact a root-shoot), one to the left and the bigger behind the leaves of my raspberries and going straight up.

Well, at least rodents are not bothering the main roots.

 

Interesting pic JD.

Do you expect that the pot will limit the size of the tree or at least slow the growth? (I understand that it doesn't have a bottom.)

Hi,
I'm expecting that too. This tree currently has shorter inter-nodal spaces, which is a searched side effect !
Because the pot (limiter) is not so big (like the usual 80L trashcan - must be 1or2gal), this tree is not blocked that much to access surrounding dirt/water/humidity.
And so she doesn't suffer during the dry weeks of summer.
Funny, I didn't see the roots grow out. I just discovered them this Spring while shoveling around the tree.

The only time I have seen that is when the fig is growing in a high humidity environment. 
Have you had a lot of rain or high humidity days lately?

Another possibility is that at one point there was soil above the rim of the pot.  Perhaps after the pot was placed, there was a rain or something else that caused some soil to be dumped on the top.  It's actually possible that even just some leaves accumulating on top would create a moist enough environment for a root to grow up and over the edge.  Then once the tip gets over and into the soil outside of the pot, it's free to grow into the soil.  Then rain comes and washes the soil (or leaves) away. 

Another point to note is that air will only prune the newly formed tip of a root.  An established root, as you can see, is hardier and woodier and will not shrivel in air. 

Well air pruning doesn't kill roots for one. A root will grow 180 degrees in the other direction when it hits an air pot side. In regular pots the roots just circle. In air pots they grow inward instead of circling. Roots actually need air, why perlite is used. To keep water flowing so air will not be shut off. I myself add DE to store water also.

It looks to me like the roots are coming up for water so possibly your tree is not getting the deep watering it needs.  Or, the soil may need aeration so the roots are taking the route of least resistance. I had the same thing happen with my avocado tree.