Study Tree Growth

Data on tree growth used in the Case Study published in the September 1995 issue of the Canadian Journal of Statistics was provided by Dr. Fernando Camacho from Ontario Hydro Technologies and forms the basis of a study that investigates the effects of the growth regulators Paclobutrazol (PP 333) and Flurprimidol (EL-500) on the number and length of internodes in terminal sprouts formed on trimmed silver maple trees the trimming of trees under distribution lines on city streets and in rural areas being a significant problem and expense for electrical utilities such operations are performed at intervals of one to eight years depending on the species' growth rate and the required clearance Ontario Hydro trims around 500,000 trees per year at a cost of approximately $25 per tree much effort has been directed toward developing chemicals for the horticultural industry to retard the growth of woody and herbaceous plants PP 333 and EL-500 represent a group of new growth regulators that control tree growth effectively without causing noticeable injury symptoms these substances have been applied as foliar sprays soil drenches or trunk injections with results indicating a reduction in sprout growth the study's goal was to evaluate the sprout length the length of the individual internodes and the number of internodes following the injection of silver maple trees with these growth regulators the experiment conducted in May 1985 involved 12-year-old multistemmed silver maple trees at Wesleyville Ontario trunk-injected with methanolic solutions of EL-500 and PP-333 using two application rates (20 g/L and 4 g/L) the formula for the injection volume based on tree diameter was applied ten trees per group were assigned to control and experimental sets trees were trimmed prior to injection and twenty months later samples were taken from limbs of each tree to measure sprout characteristics internode lengths were expressed to one decimal place and specific dataset records include sprout number treatment tree and branch identifiers total sprout length internode number and individual internode lengths providing a comprehensive resource for analysis.