Herbicides for Weed Control in Leatherleaf Fern1

Abstract

Four herbicides, alone and/or in combination, were evaluated for weed control in beds of leatherleaf fern [Rumohra adiantiformis (G. Forst) Ching]. Fair winter weed, predominantly chick weed [Stellaria media (L.) Cyr.], control was obtained with simazine [2-chloro-4,6-bis(ethylamino)-s-triazine] at 2 kg active ingredient (a.i.)/ha, simazine + metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] at 1.1 + 2.2 kg a.i./ha and oxadiazon [2-terf-butyl-4-(2,4-dichloro-5-isopropoxyphenyl)-Δ2-1,3,4-oxadiazolin-5-one] + simazine at 1.1 + 1.1 kg a.i./ha. Oxadiazon + simazine, oxadiazon + metolachlor at 1.1 + 2.2 kg a.i./ha, and simazine + metolachlor controlled spring weeds. All herbicide treatments gave fair weed control in summer. Except for simazine applied alone, none of the treatments injured leatherleaf fern visibly. Oxadiazon + metolachlor, oxadiazon + simazine, and simazine + metolachlor reduced winter weeding times. All combination treatments reduced spring weeding times, but none of the treatments reduced summer weeding times. No treatment reduced fern yield or affected average frond weights. Frond length and frond weight were positively correlated (r = 0.74).