this undergraduate thesis explores an observation made by the city of thunder bay’s urban forestry department staff of treeazin injected green ash tree’s limbs and branches failing shortly after being injected. the objective of the study was to determine whether or not treeazin injections were directly causing new woody growth to be less structural, resulting in failing limbs and branches. for this study, four green ash street trees were removed from the northwood neighborhood of thunder bay, two injected and two not injected, to be tested for their mechanical properties. due to covid-19, and the inability to access testing facilities, only density measures for each tree could be obtained and tested. after statistical analysis of samples conditioned to 12% moisture content, it was observed that injected samples all had higher density values than not injected samples suggesting the failures were due to alternative factors. alternative factors including environmental factors and quality of injection were discussed and concluded to be the likely cause of branch failures in green ash trees in the city of thunder bay.