Assessing economic impact of weed control strategies in autumn sown wheat crops in New Zealand

Abstract

Globally, weeds are major biotic stressors in crop production systems causing yield loses of up to 35%. Herbicides have been a cost-effective way to mitigate yield losses due to weeds. However, extensive use has resulted in the development of herbicide resistance across multiple weed species and herbicide mode-of action groups. An Australian study reported the overall cost of weeds to grain growers was $3.5 billion. There is an opportunity for similar evaluations to provide value to the New Zealand cropping industry. In the face of herbicide resistance and increasing weed control costs, the development of economically viable integrated weed management strategies are increasingly important. Crop competition is such a tool that has been successfully implemented overseas but assessment in New Zealand context. This non-chemical weed control option may provide the opportunity to reduce herbicide use, mitigate herbicide resistance, reducing the cost of weed management programmes while increasing life expectancy of chemicals. This study will seek to quantify the economics of weed management in autumn sown wheat and test whether competitive wheat cultivars with different growth characteristics is a viable non-chemical weed control option for New Zealand growers. The experimental design features a paired plot Youden design that incorporates three herbicide management programmes and three autumn-sown wheat cultivars. The aim of this study is to develop integrated weed management programmes that balance profitability, crop productivity, acceptable levels of weed control and herbicide resistance management.