It's been many years since I checked under the mulch around my Acer p. 'Osakazuki' so I was pretty shocked today to find what looks like girdling roots. Also there's a wound in the trunk a few inches up from the ground. The tree itself looks great so I'd like to just leave well enough alone unless you experts think otherwise. Thanks for any suggestions you can give me.
It doesn't look like it to me, but you need to clear away the soil a bit deeper to be sure. Girdling roots all start when the tree was in a nursery pot. What tends to happen is that the roots start circling when they encounter the pot wall, then they begin circling around against the pot wall. This starts when the tree is relatively young, but as the years go by the roots get thicker and one can often wind up with a heavy root circling the trunk. This ultimately shuts off the supply of carbohydrates feeding the roots and the auxin to stimulate their growth because it encircles the trunk. Once this has happened it begets a dead tree when the roots exhaust their stored carbohydrates, which happens quite quickly after 12 to 18 months after the trunk is girdled (which means the phloem and cambium are disrupted, just like removing a ring of bark from around the stem). All it takes for the tree to survive, though, is an open line down the trunk. The surprising thing is that roots can look to be innoculously circling when the tree is planted, but they keep growing in the same way. The only fix is to cut them when you find them, which IMHO is the reason many a gardener's practice is to vertically score the root 'ball' when the tree is removed from the nursery pot for planting. Of course it is a good idea when potting the tree into a larger/decorative pot too. Your pictures show some crossing roots that don't represent any serious horticultural problem. Even though the roots are not particularly attractive (ugly?), they do not appear to be a horticultural problem, IMHO. BUT again, you should look a little deeper down to be sure.
Thank you @Osoyoung. I usually check for potentially girdling roots but maybe not so closely as I should have when when I planted that maple 10 or more years ago. Anyway, I'll try to check a bit deeper.
@Margot, I gree with everything J @Osoyoung says in his post. I would also check a little more beneath the surface. There is potential IMO looking at photo (2).
