Barley grass control with herbicides in subterranean clover. 2. Effect on pasture and wheat in the year following spraying

Abstract

Barley grass (Hordeum spp.) in a subterranean clover pasture was controlled using herbicides at different growth stages in 1988. The residual effects of these treatments on a naturally regenerating pasture and on wheat were investigated in 1989. Barley grass control carried over into 1989 but there was no increase in subterranean clover seedling density 1 resulting from legume dominance in 1988. Dry matter I production in early winter, on plots treated with herbicide in 1988, was reduced by up to 62% compared with unsprayed pasture, and the proportion of other broadleaf weed species increased. Wheat yields were increased by 3-11% where barley grass was controlled with fluazifop-p in the previous pasture. Available soil moisture at sowing was lowest following pasture that was unsprayed in 1988. No effect on the level of take-all (caused by Gaumannomyces graminis var. tritici) was evident. A replacement graminaceous species should be introduced into the pasture following barley grass control so that animal production and soil conservation are not disadvantaged. A disease break for a following cereal crop can be maintained by sowing an oat cultivar that is resistant to cereal cyst nematode (Heterodera avenae).