This field trial at Frances was undertaken to investigate factorial combinations of sowing time, seed rate and herbicides on the management of annual ryegrass in barley.

The average seedbank of annual ryegrass (ARG) at the site was quite low (472 ± 143 seeds/m2), which was reflected in low plant density at the site. ARG plant density was significantly influenced by the time of sowing (P=0.037), and herbicide treatment (P=0.009). There was a 37% reduction in ARG plant density between TOS 1 (20 plants/m2) and TOS 2 (13 plants/m2). Herbicide treatment had a significant effect on ARG plant density, with Boxer Gold showing lower efficacy on ARG than Treflan and Boxer Gold + Treflan. Unlike ARG plant density, ARG spike density was not influenced by time of sowing (P=0.171). ARG spike density was significantly influenced by barley seed rate (P=0.016), herbicide treatment (P=0.01) and the interaction between TOS and herbicide treatment (P=0.019). ARG spike density was 34% and 40% lower in medium and high seed rates respectively when compared to the low seed rate. These results suggest an improvement in ARG suppression from increasing barley competitiveness with increased seed rate. Barley grain yield at the site averaged 6.6 t/ha. Herbicide treatment had a small (4-6%), but significant effect (P=0.009) on grain yield with Boxer Gold < Treflan ≤ Boxer Gold + Treflan for barley yield.