• Haywood, James Davis
  University of Maine Graduate School
  

Balsam fir (Abies balsamea (L.) Mill.), red spruce (Pieca rubens Sarg.), and white spruce (Picea glauea (Moench) Voss) seedlings were treated with 2,4,5-T, Amitrole, and glyphosate during active springtime growth. The objective was to determine whether these herbicides could severely injure balsam fir while not harming either red or white spruce. The research was conducted on three locations in the Penobscot Experimental Forest, U.S. Forest Service, Bradley, Maine, over a two year period in 1976 and 1977. Treatment dates were determined by the beginning of balsam fir bud swell, bud break, and the end of current-year shoot elongation. The herbicides were formulated in a water carrier and sprayed on the individual seedlings until the foliage was dripping wet. Three criteria were used to determine chemical injury--injury to the current-year shoots, reduction in the length of the terminal and terminal-laterals, and defoliation of the one-year-old, two-year- old, and three-year-old needles.