Occurrence of weeds in the perennial pasture zone of New South Wales
J.J. Dellow, G.C. Wilson, W.McG. King and B.A. Auld, CRC for Weed Management Systems and New South Wales Agriculture, Orange Agricultural Institute, Forest Road, Orange, New South Wales 2800, Australia.
A survey was conducted of the vegetation of the temperate perennial pasture zone of New South Wales in spring 1999. Less than 10% of the paddocks surveyed had the 50% 'improved' perennial grass level considered desirable for maximum production. On average, perennial grasses formed about a third of the pasture biomass and, when only the 'improved' perennial species were considered, this figure dropped to around a quarter of the biomass. As a group, legumes were almost ubiquitous (99% frequency) and relatively abundant (22% of the pasture biomass, on average) and broadleaf weeds were similarly widespread but less abundant (<9% of the biomass). Annual grasses (especially Vulpia spp.) formed, on average, 26% of the pasture biomass. This level of abundance of annual grass weeds has an estimated opportunity cost of about $33 per hectare per year - representing a total loss of more than $230 million to the New South Wales pastoral industry. Low-cost pasture management technologies that limit the abundance of annual grasses do exist. Their adoption and adaptation to local conditions need to be promoted within an integrated pasture management strategy.
Plant Protection Quarterly (2002) 17 (1) 12-16.