The International Society of Arboriculture Turns 100!

ISA is born.

In 1924 members of the Connecticut Tree Protective Association convened a meeting that would plant the seed for an organization that revolutionized the tree care industry.  It was this gathering that became the first of 100 annual conferences that evolved into today’s International Society of Arboriculture (ISA).  The organization has its roots combining the knowledge of  progressive commercial arborists and tree researchers.

The Shade Tree Conference, which became the National Shade Tree Conference (NSTC) first met in 1924, in Stamford, Connecticut.

Tree care companies led the movement.

F.A. Bartlett, president of The F.A. Bartlett Tree Expert Company was a principal figure in organizing this conference with only 36 participants. This marked the formal beginning of arboriculture in the United States, even though in England the term had been used for over 300 years, to differentiate tree care from forestry.


In the 1930s with the proliferation of utility wires across North America, arboriculture was amplified as the Davey, Bartlett and Asplundh companies took on line-clearing contracts.

The NSTC was growing and spreading at a rate the founders never expected, and in the 1940s regional chapters started to form, and membership grew.

One world of trees…

In the 1960s Canada felt misrepresented by the word “national”  in NSTC. So, in 1961, the organization became the International Shade Tree Conference (ISTC).

The small group became more organized, and to commemorate the United States Bicentennial they formed the International Society of Arboriculture on January 1st, 1976.

Arborist Certification

in 1992, ISA launched an unprecedented program of Arborist Certification on an international scale.  The goal was to raise the level of professionalism in arboriculture by educating the providers of tree care services, and bringing public awareness.

The Florida Chapter of the ISA, which has a separate governing board, was inaugurated in 1996.   It is the only chapter that now offers the PPQ, or Prescription Pruning Qualification (PPQ), a collaboration with UF/IFAS and the leadership of the Florida Chapter.  This qualification seeks to streamline the process and practice of structural pruning.

Prophetic words…

“The time has come when tree planting and tree culture must be studied in connection with the physiology of plant life.  If this is not done, a calamity will befall the inhabitants of  these fruitful regions to an extent that no human mind can conceive.”  John Davey

In 1901, John Davey, founder of the Davey Tree Expert Company, wrote these words in his book, The Tree Doctor.  These same words can be echoed today, as we continue to grapple with climate change, overdevelopment and the management of tree canopies all over the world.

Hire only ISA Certified Arborists.

Whether you are a professional arborist, or someone who seeks to better understand trees, ISA has a wealth of information to share.  If you are hiring an arborist to trim your trees, hire only ISA Certified Arborists.  Your trees are worth it and so are you.

Happy 100th Birthday, ISA!  You make our world a better place.




donna corbelli castro
Posted: July 2, 2024

Category: Florida-Friendly Landscaping, Forests, Home Management, Horticulture, Professional Development, UF/IFAS Extension,
Tags: Arboriculture, Arborist Certification, Climate Change, ISA, ISA Certification, ISA Turns 100, Newsletter, Trees, Urban Horticulture

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