Tolerance of bare-root ornamental perennials to selected herbicides

Abstract

The market for ornamental perennials astilbe [[Astilbe japonica (Morr. & Dcne.) Gray], A. × arendsii, A. chinensis (Maxim.) Franch. & Savat.], stonecrop [Sedum roseum (L.) Scop.], hosta (Hosta fortunei Baker.), and daylily (Hemerocallis fulva L.) has expanded in Canada. We evaluated the tolerance of these ornamental species to selected herbicides applied preemergence and postemergence in Nova Scotia in 2002 and 2003. Napropamide, linuron, metribuzin, pendimethalin, metolachlor, pronamide, and oxyfluorfen may be used preemergence in hosta. Napropamide, pendimethalin, metolachlor, pronamide, and oxyfluorfen may be applied preemergence in all astilbe species. Linuron could be used preemergence in astilbe species japonica and arendsii, but not in chinensis. Napropamide, linuron, pendimethalin, metolachlor, pronamide, and oxyfluorfen may be suitable preemergence in both daylily and stonecrop. Bentazon, fluazifop-P, pendimethalin, pronamide, thifensulfuron, rimsulfuron, dithiopyr, and isoxaben can be used postemergence in hosta. Fluazifop-P, pendimethalin, pronamide, chlorimuron, thifensulfuron, rimsulfuron, dithiopyr, and isoxaben can be used postemergence in all three astilbe species. Bentazon, fluazifop-P, pendimethalin, pronamide, chlorimuron, rimsulfuron, dithiopyr, and isoxaben can be used postemergence in daylily. Bentazon, pendimethalin, pronamide, chlorimuron, nicosulfuron, nico-rimsulfuron, thifensulfuron, dithiopyr, and isoxaben can be used postemergence in stonecrop. Key words: Bare root perennials, herbicide efficacy, Astilbe, Sedum, Hosta, Hemerocallis, ornamentals, nursery crops