Economic and environmental assessment of the performance of reduced rates of two post-emergence herbicides in an arid irrigated production system of central Australia: a pilot study

Martin Hidalgo, Glen Oliver and S. Raghu, Arid Zone Research Institute, Department of Resources, Northern Territory Government, PO Box 8760, Alice Springs, Northern Territory 0871, Australia.


The use of herbicides can add considerable costs to production practices on marginal land, and increase risks to environmental and human health. The relative performance of label and sub-label rates of the post-emergence herbicides (Amitrole T and Basta) and label rates of Roundup was compared within a benefit-cost analysis framework, in an arid irrigated production system in central Australia. Sub-label rates of Amitrole T and Basta were as effective at weed suppression as their label rates (LR); approximately 50% reduction in weed cover was recorded across the trial with both label and sub-label rates for both herbicides.

The sub-label rates of Amitrole T (75% LR and 65% LR) and Basta (75% LR) had a statistically similar economic benefit-cost ratio as their corresponding LRs, and the LR of Roundup. The equivalence of Basta’s sub-label rate in terms of economic efficiency is even more noteworthy if one takes into account that significantly lower amounts of the herbicide needed to be applied to achieve the level of weed suppression obtained using the label rate of Roundup. Our results suggest ways to improve the economic and environmental efficiencies of herbicide use in the arid, irrigated production systems of central Australia.

Keywords: Sub-label rates, buffel grass, arid-zone weeds, cost-benefit analysis, sustainability.


Plant Protection Quarterly (2011) 26 (2) 49-53.