Quantifying the economic impact of weeds on the Australian grain and cotton cropping systems

Weeds should be identified as plants that have negative economic, ecological and/or social impacts. The magnitude of these impacts is an important determinant of the seriousness of a weed species. There are hundreds of weed species present in the cropping systems of Australia with the individual impact each of these species on the farming system being different and can change between geographic regions and over time. The cost to control these weeds represents a very significant input cost to growers. The last major review of the economic costs of weeds to Australian grain cropping was conducted in 2013-2014 and estimated the total cost of weeds to be $3.3B per annum, or $146/ha. Expenditure on weed control considerably out weights the revenue loss due to weeds - $2.5B compared to $745M. This research culminated in the publication the 'Impact of Weeds on Australian Grain Production – The cost of weeds to Australian grain growers and the adoption of weed management and tillage practices' (Llewellyn et al 2016). This study has been widely cited in the grains industry and well used in investment planning and justification. Given the actual survey data used in that study is almost 10 years old, and a greater emphasis on understanding the value pool for weeds RDE, there is a need to re-quantify the economic impact of weeds to Australian grain and cotton cropping systems. Understanding the weed management practices associated with weed costs is also critical to RDE planning.