Alex Shigo’s reference text “Modern Arboriculture” is recommended by the International Society of Arboriculture for arborists, landscape architects, urban foresters, fruit growers and students. He was a leader in arboriculture research and study. “Deep injection holes into trees that form tyloses makes no sense.” Tyloses is a sap like compound that forms in response to wounding and plug the damaged growth rings so they can no longer conduct water and nutrients. Holes drilled according to specifications also can cause problems by allowing air into the vascular system which can disrupt water and nutrient movement and provide entry points for pests and disease. For more information, click here.