| [College of ACES] | [University of Illinois] | [Illinois CES] |
There is a Natspec document in Australia called Purchasing
Landscape Trees by Ross Clarke (ISBN 0 646 25547 9). It is
probably the best set of specs you could hope for. The problem
is even Ross has problems meeting his own standards some of the
time and buying matterial of this standard is hard work (destructive
testing etc.)
The other issue you may want to look at is the breeding program eg
genetic selection, first order lateral root numbers etc.