Table 2. Mean length (in cm) of columns of discoloration and dieback after 1 year of experiments testing 4 variations of rosin acids on 12 red maple trees.  Each tree had 3 drill wounds, each treated with a different material, and 3 nontreated control wounds; a total of 15 drill wounds at 3 whorls on the trunk of each tree. Dieback measurements on 4 trees.