Dr. Alex Shigo

Known as the “Father of Modern Agriculture”.

Dr. Alex L. Shigo (8 May 1930 – 6 October 2006) was a biologist, plant pathologist with the United States Forest Service whose studies of tree decay resulted in many improvements to standard arboricultural practices. He travelled and lectured widely to promote understanding of tree biology among arborists and foresters. His large body of primary research serves as a broad foundation for further research in tree biology.


Early in his career, the first one-man chainsaws became available. These enabled him to prepare longitudinal sections of trees, which allowed him to study the longitudinal spread of decay organisms within them. A major discovery from this work was that trees have ways of walling off decaying tissues, which he named Compartmentalization of Decay in Trees. This led to reassessment of arboricultural practices such as pruning techniques and cavity treatments, which showed that many of these actually promoted decay or were ineffective. The ANSI A-300 Pruning Standard reflects his recommendations.

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