Uniconazole Retards Growth and Increases Flowering of Young Macadamia Trees

Abstract

Uniconazole (0.2 g a.i. per cm trunk diameter) was applied as a soil drench to 2-year-old potted macadamia ( Macadamia integrifolia Maiden & Betche) trees, and reapplied yearly for 4 additional years. Uniconazole significantly reduced tree height and trunk diameter 1 year after initial treatment, and suppressed shoot extension for the duration of the study. It significantly increased flowering the second year after initial treatment, the first year that both the control and treated trees flowered. Subsequently, no differences in flowering were observed until the fifth year, when flowering was significantly less in treated trees, probably due to reduced shoot and trunk growth and tip dieback. Chemical name used: E-1-(p-chlorophenyl)-4,-4-dimethyl-2-(1,2,4-triazole-1-penten-3-ol) (uniconazole).