We remove all the baskets on our trees. We have not had any problems. If the root ball does start to come apart, we just stake the tree and they have all been fine. I dont know that the basket actually causes the girdling roots but most times the trees are too deep in the basket and that does cause g-roots. There is lots of research going into this subject and I think before too long the standards will be re-written. Ok, maybe that is wishfull thinking.
Don't expect great changes soon--the research results are spotty because they are short term, speaking in tree time. See Gilman's recent work here:
http://hort.ifas.ufl.edu/woody/documents/gstc2006.pdf
Some specifications still ignore the requirement in ANSI A300 (Part 6)-2005, 63.6.2.3, “The bottom of the trunk flare SHALL be at or above finished grade”. Instead, they instruct the landscape contractors to plant the root BALL at ground level, so the landscapers obediently follow this instruction, with disastrous consequences.
Arborists should have the ANSI standard—available from TCIA—in hand when they talk to growers and landscape architects and landscapers about deep planting. When these professionals see with their own eyes that the American Nursery and Landscape Association and the American Society of Landscape Architects are represented in ANSI, they will realize that they don’t have a stem to stand on when they bury trees. The entire green industry agrees that we should always be able to find the trunk flare.
Technically, the rootball does not even include the soil above the trunk flare. It is “measured from the bottom of the trunk flare to the bottom of the ball.” (ANSI A300 (Part 6)-2005, 63.6.1.2) If the flare is found and set to grade, in a hole “a minimum of 1.5 times the diameter of the root ball” (63.6.1.4), with mulch “applied near, but not touching the trunk” (63.6.2.9), the tree roots will not need to grow up in search of oxygen. But even if these standards are followed at planting time, the tree may not grow well. For some reason, there is nothing in the standard about the making sure the roots, at least the major roots, are growing away from the stem.
Why not? You’ll have to ask your organization’s representative to the ANSI committee, and get your comments in before the standard is revised again in 2010. The ANSI pruning standard does not currently cover root pruning—perhaps with the right kind of input, that standard can change to provide needed guidance on this simple act of arboriculture.