I was shuffling through some photos today, hunting for an illustration of girdling roots, thinking that I’d use one of a myriad of pix I have of subgrade snarlups. But this picture popped up, and it seemed useful to show how a root that seems insignificant in infancy can grow to have an adverse effect on the health of the tree from which it springs.
These two girdling roots started out as thin, wirelike strands growing past the trunk of a sapling.
This tree is a Norway maple in our backyard (yes, we still have a couple of them). From its position in the lawn I’m betting that someone planted it. At the time of planting, it would have been a small tree — perhaps a 5-foot sapling dug from the yard’s border and moved to the lawn, or maybe one of the 1.5″ caliper whips given away by our town one year.
If you envision the young transplant then, you’ll imagine those two girdling roots as a couple of very thin, quite insignificant-looking roots, running parallel to and about two feet away from the trunk of that skinny tree. They might have been considered circling roots, they might simply have just gotten twisted the wrong way in planting and continued to grow straight past the trunk.
As the tree grew in height it also grew in girth; the crown branched out, the trunk got thicker. As the trunk got thicker, the roots and branches thickened. A harmless condition in the tree’s juvenile days has turned into a bit of a problem in its middle age. Now the skinny roots have fattened up, and have begun to squeeze the vascular tissue in the roots runny radially out from the trunk. Bark above the girdling roots is traumatized (and not just by the squirrels that run up and down every morning) by constriction. There’s a bit of dieback in the crown this year — though that may have been caused by something else (winter breakage invaded by fungus? Norway maple cussedness?)
The solution? Chiseling the girdling roots away from the constricted roots to free up that vascular system could help, though at this stage it would be interesting to see if that section of root and trunk flare could really recover. I have been using the Norway maples in the yard — the two mature ones, and a small thicket of saplings — as a small laboratory, so will keep watching to see what happens here. Feel free to comment below….
Deborah Howe
Taking Place In The Trees 
I heard recently from a friend who was going to plant a four-inch caliper Tulip tree. I wrote him “The Tulip is a noble tree. Plant it high. See this: http://takingplace.net/2009/04/02/buried-alive/”
He planted it high, and he confirmed that 1.) there were several inches of dirt above the root flare, and that 2.) they removed it, in the process finding 3.) a number of new adventitious roots, including 4.) several that seemed to be starting to encircle the trunk.
So, Deb, thank you for making it possible for me to save a tree with just a few keystrokes and a url!