The Pennsylvania-Delaware Chapter of the International Society of Arboriculture was founded in 1960. Their mission is to provide quality educational opportunities for its members. There are currently over eight hundred members in the chapter including commercial, consulting, municipal, and utility arborists, researchers and educators, horticulturists, and individuals interested in the care of trees and landscapes. Landscape professionals working with trees are encourages to become a certified arborist. A snapshot of their home web page is shown below with a link to take you to their page.
To go to their web page for more information the link is http://www.penndelisa.org/