Dr. Shigo spent most of his professional career with the United States Forest Service where he was to develop a tree cutting technique that led to important discoveries, many of which were incorporated into CODIT (Compartmentalization of Decay in Trees). CODIT became a groundbreaking biological idea that led to many changes and additions to commercial tree care practices.
After retiring from the Forest Service in 1988, Dr. Shigo began another career speaking and writing about trees. He authored over 270 publications, including many research papers, books, pamphlets, CDs, and DVDs. He continued to operate his book company, Shigo and Trees, Associates LLC with help from his wife, Marilyn Shigo until his death in 2006.
USFS Photo of a Shigo Tree "Autopsy"