Estimating the economic cost of weeds in Australian annual winter crops

Abstract

Abstract An analysis of the annual costs of weeds in seven winter crops across Australia demonstrated that the most important 15 weed species cause substantial annual costs in both financial and economic terms. Using survey data captured over the 1998–1999 growing season, the financial cost of these weeds in seven crops was estimated to be AU$1,182 million. The main components of this cost were herbicides (AU$571 million), the competitive effects of residual weeds (AU$380 million), and tillage (AU$206 million) while weed contamination of grain was a minor cost (AU$25 million). Across all regions, the most economically important weeds were annual ryegrass, wild oats, and wild radish, although there were regional differences in importance. An economic surplus analysis determined the annual economic cost of weeds in annual winter crops to be AU$1,279 million. This surplus loss represented 17% of the gross value of Australian grain and oilseed production in 1998–1999. Australian grain producers incurred a major loss, with a reduction in producer surplus of AU$1,047 million. Australian grain consumers had a large consumer surplus loss (AU$229 million), while international consumers suffered a small loss and international grain producers gained a small producer surplus from the higher grain prices.