Effect of Trunk Injection of Uniconazole on the Growth of Norway Maple and Green Ash over Four Years

Abstract

In a 4-year field study, Norway maple {Acer platanoides) and green ash (Fraxinus pennsylvanica) trees (average dbh at time of treatment: 22.4 and 13.4 cm, respectively) were trimmed to a uniform height and trunk injected with the growth regulator uniconazole in the spring of 1988. The rates of application were 0.1 g and 0.2 g a.i. per cm trunk diameterforthe maple and ash, respectively. The growth of the trees, in terms of increase in height and in trunk diameter, was determined each fall until 1991. Growth of the ash was significantly inhibited for the four years (43% in height and 33% in diameter). Increase in trunk diameter of maple was significantly inhibited (43%), but there was no significant inhibition of increase in height. Some injection holes in the maple bled after application, but none bled in the ash. No bark damage was seen in the ash, but in the maple some bark cracks were observed.