There was a discussion, not too long ago on interesting materials to fill holes on fruit trees.
Yesterday, I got some hard clay, potter's quality, which is to be found on the bed at the bottom of a stream nearby. You can collect it in slabs and it seems almost entirely free of organic matters. It can be broken in pieces that you can work by applying pressure and a sliding motion of the thumb to fill bad holes, crevasses and unsightly damages to trees.
Once dried, the grains are extremely fine, dust in fact, and the filling appear to stick very well in place. It also absorbs moisture readily so I imagine it will never get completely solid, nor crack, and it can reshape itself to accomodate the growth of the tree.
It seems to work very nicely.
Hélène, zone 3
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