Vegetative growth responses of florist azaleas to dikegulac, GA4+7, and 6-benzylamino purine

Dikegulac, dikegulac + GA 4+7 , BA, and Promalin (GA 4+7 + BA) were evaluated as lateral shoot-inducing agents on greenhouse forcing azalea, Rhododendron cultivars Gloria and Prize. The addition of GA 4+7 (1000 or 2000 mg.L -1 ) to a commercial rate of dikegulac (3900 mg.L -1 ) did not effectively increase plant diameter or leafwidth compared to plants sprayed with dikegulac alone. The combination of dikegulac and GA 4+7 (3900 + 2000 mg.L -1 , respectively) was more phytotoxic than dikegulac alone. Foliar sprays of BA and Promalin at 1000 and 2000 mg.L -1 and 1000 and 1816 mg.L -1 , respectively, did not increase lateral shoot count. Neither the addition of GA 4+7 to dikegulac nor the use of Promalin is a viable alternative to dikegulac application for inducing lateral branch development of dikegulac-sensitive cultivars. Chemical names used: Na 2,3:4,6-Bis-0-(1-methylethylidene)-a-L-xylo-2-hexulofuranosonic acid (dikegulac), (1α,2β,4aα,4bβ,10β)-2,4a,7-trihydroxy-1-methyl-8-methylenegibb-3-ene-1,10-dicarboxylic acid 1,4a-lactone (GA 4+7 ), N-(phenylmethyl)-lH-purin-6-amine (BA), and Promalin [1:1 (wt/wt) GA 4+7 and BA].