Your local garden center, county extension agent, or city arborists are also excellent sources of
information if you should have further questions. They may also be able to refer you to ISA
Developed by the International Society of Arboriculture (ISA), a non-profit organization
supporting tree care research around the world and is dedicated to the care and preservation of
shade and ornamental trees.
For further information, contact:
ISA, P.O. Box 3129, Champaign, IL 61826-3129, USA.