Wild oat density and the duration of wild oat competition as it influences wheat growth and yield

Abstract

The effects of removing wild oats (Avena spp.) from wheat (cv. Gamut) at different stages of wheat growth were investigated in three replicated factorial field experiments at the Tamworth Agricultural Research Centre. In addition, two wild oat densities were compared in the first experiment, and handpulling wild oats was compared with cutting and a shielded paraquat spray in the second experiment. Wheat yield was linearly reduced by up to 1.025 g m-2 day-1 for the duration of wild oat competition. Reductions in tiller number and dry matter yield measured at maturity and the number of tillers per plant recorded at the 5-6 leaf stage were also proportional to the time wild oats were allowed to compete with the wheat. This competitive effect of wild oats increased with increasing weed density. Handpulling and cutting wild oats gave similar measured competitive effects whereas the paraquat spray applied at the 2-3 leaf stage of wheat reduced wheat density.