There's a couple guys up here in my neck of the woods that have been doing a lot of research/presentations over the last several years regarding tree defects that result first from poor quality nursery stock and second from poor planting/installation. This seems to be a nationwide epidemic problem in the green industry involving almost all nurseries and almost all landscape contractors. Lots of these problems that began in the early stages of the tree's development end up manifesting themselves into the reasons arborists get calls from worried homeowners (whether it be tree failure, disease, pest, etc.) There's a link here but since it's separated by many years and spread over 2 or more professions it's hard to put 2 and 2 together. They're beginning to make the correlation. These guys are interested in rewriting nursery stock standards. And they're keeping busy by getting back to the old fashioned ways of transplanting trees (some very very large) bare root. It's some very interesting stuff. If you guys ever get a chance to hear them speak on this, I recommend it. Their talks are well thought out and well put together and loaded with interesting pictures. Their names are Jim Flott & Rich Baker.