Control of black pigweed (Trianthema portulacastrum) with trifluralin for pasture legume establishment

Abstract

Trifluralin was tested for the control of black pigweed in establishing stands of a range of pasture legumes. Increasing the rate of herbicide up to 1 lb/ ac active ingredient increasingly depressed the stand and dry-matter yield of black pigweed, the most effective rates being 1/4 and 1/2 lb/ac. Legume populations were only weakly influenced by trifluralin rate but yield reaction varied with species. Siratro and Hunter River lucerne, and to a lesser extent Clitoria ternatea, reacted favourably to reduced black pigweed stand. Cooper glycine, Archer axillaris and Peru leucaena were not affected by the control of black pigweed. Depth of cultivation after application had no major effect. The main effect was highly significant on black pigweed yield and stand but was of minor· importance compared with rate of application.