Economic analysis of integrated management of wild oats involving fallow, herbicide and crop rotational options

Summary. The primary objective of this study was to estimate the economic benefits associated with an integrated weed management approach for wild oats (Avena fatua and A. ludoviciana) in northern New South Wales involving chemical and non-chemical controls. The paper presents a framework for assessing the population dynamics of wild oats and the economics of a range of control options over 15 years. Wild oats is a weed primarily of winter crops which, as a consequence of its persistence and its impact upon yields, leads to significant economic losses in the grain growing regions of Australia. In this study, a dynamic programming model is developed to examine the impact of a range of management strategies for the control of wild oats in wheat. The strategies evaluated include conventional herbicide control to reduce weed densities, the use of selective herbicides to reduce seed set of the weed, and summer crop and winter fallow rotational options which provide a break in the cereal cycle and allow accelerated control of wild oat populations. The hypothesis for the study, that strategies which involve measures that directly reduce seed production and minimise wild oats seed bank populations will yield the greatest economic benefit, is acceptable based on the findings of the study. The work also shows that a dynamic programming model provides a means of determining the optimal combination of strategies over time for various initial values of the seed bank. The methodology is considered to have general application as a framework for evaluating the economics of weed control problems in annual cropping systems.