Growth, Biomass, and Trim/Chip Time Reduction Following Application of Flurprimidol Tree Growth Regulator

Abstract

Two application methods for the tree growth regulator flurprimidol were compared to untreated trees three years after treatment. Silver maple in Ohio, water and willow oak in Virginia, red oak and red maple in Maine, and Norway maple in Pennsylvania, at locations representing five different utilities, were treated with basal soil drench applications at 0.5, 0.75, and 1.0 grams of active ingredient (gai) per inch diameter at breast height (dbh) and with implant applications at 0.5 and 0.75 gai per inch dbh in 1989. Trees were revisited three years after application and assessed for growth suppression using three techniques. Measurement of the seven longest shoots in each tree were taken to the nearest inch for the growth occurring from 1989 to 1992. All trees were trimmed to utility companies' specifications, and the green biomass removed was weighed and chipped. Green biomass weight and actual trim/chip time was recorded for each tree. Significant differences were detected between the untreated trees and the treated trees; however, differences due to application techniques and dose rates were irregular and seldom significant. Overall, for the four species across all sites,there was a 63 percent reduction in shoot elongation, a 75 percent reduction in biomass, and a 55 percent reduction in trim and chip time when tree growth regulators were used.