Dikegulac Sodium and Benzyladenine Effects on Six Landscape Tree Species during Container Production

Abstract

A study was conducted to evaluate dikegulac sodium (dikegulac) and benzyladenine (BA) as branching agents on landscape trees during production. Common among the six species in this two-year study was an increase in new shoot development following the application of dikegulac. Relative to shoot counts of nontreated plants, trees treated with a single foliar application of 800 to 3200 ppm of dikegulac had an increase in shoot numbers of 29 to 107% in Japanese maple, 75 to 158% in red maple, 67% in redbud, 50 to 65% in bald cypress, and 56 to 103% in black gum. Nontreated plants of green ash formed only one or two lateral shoots in 2011, whereas dikegulac-treated green ash had 10 to 12 new shoots. In 2012, green ash treated with 200 to 800 ppm of dikegulac developed 100 to 150% more new shoots than nontreated green ash. Foliage of all species, except Japanese maple, was injured to varying degrees by dikegulac, but the injury dissipated over the growing season. BA promoted increased shoot development only in bald cypress, and canopies of that species were visually fuller and more compact than those of bald cypress treated with dikegulac.