Concentration Response of Zonal Geranium and Potted Chrysanthemum to Uniconazole

Uniconazole spray or drench applications to `Yours Truly' zonal geranium (Pelargonium × hortorum L.H. Bailey) and `Bright Golden Anne' and Yellow Favor' chrysanthemums [Dendranthema ×grandiflorum (Ramat.) Kitamura] were made to evaluate efficacy and identify optimum application concentrations. Spray applications at 10 mg a.i./liter retarded stem elongation in unpinched zonal geranium comparable to chlormequat at 1500 mg a.i./liter. `Bright Golden Anne' was more sensitive to uniconazole than `Yellow Favor'. Uniconazole spray concentrations of 20 to 30 mg a.i./liter retarded plant height equal to daminozide at 5000 mg a.i./liter. Chemical names used: 2-chloro-N,N,N-trimethylethanaminium chloride (chlormequat); butanedioic acid mono (2,2-dimethylhydrazide) (daminozide); (E)-(S)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-pent-1-ene-3-ol (uniconazole).