A strategic approach to weed management for the Australian Vegetable Industry: Final Report

Abstract

<p>Weeds are a persistent problem for Australian vegetable producers, with significant impacts on crop profitability, yield, quality and management. There have been substantial advances in sustainable weed management in other industries in Australia in the last 20 years, but there has been little recent attention on developing such weed control techniques in vegetables. An earlier scoping study (Hort Innovation <i>Project VG13079: Weed Management for the Vegetable Industry - Scoping Study</i>) identified current weed control strategies and research needs, and the most common weeds (e.g. fat hen, wild radish, nutgrass). This project sought to improve weed management options and information available to Australia's vegetable growers, focusing on the following industry research, development & extension priorities.</p><p> <i>Understanding weed seed banks</i>. Soil samples were collected from vegetable farms in major production regions across Australia, and weed seeds counted by species at different depths in the soil profile. The composition, diversity and size of soil seed banks varied markedly depending on location, crop/s grown, weed species present, and the specific weed and crop management practices followed. However, heavy-seeding annual broadleaf weed seeds were predominant. Research into supplementary weed control methods also contributed to an improved understanding of how some of these priority weeds may be managed. Several cultural weed management practices were assessed to determine how they can be used to reduce weed seed banks.</p><p> <i>Integrated weed management (IWM) guidelines for Australian vegetable producers</i>. All project activities (literature review, industry consultation, field data collection, and field and pot trials) contributed to guidelines on IWM strategies for Australian vegetable production. These addressed weed impacts, IWM principles and practices, and detailed descriptions of weed control methods within IWM, including implementation, integration with other methods, and advantages and disadvantages.</p><p> <i>Robust economic analysis of weed management costs</i>. Detailed farm-level economic evaluations were completed on 19 vegetable farms in four states. Across the 19 farms evaluated, the weighted average reduction in operating profit due to weeds was found to be $2,090 per hectare. About two-thirds were due to weed control costs, and one third to revenue loss due to weeds. On almost all the case study farms, farm-level impacts of introducing an 'innovative' weed control practice was evaluated against the previous approach. The economic impact of introducing a new practice was positive in 11 cases, and negative in five cases.</p><p> <i>Extension resources for weed management in vegetable production</i>. The IWM guidelines developed during the project were summarised and published in Australia's first Vegetable Industry Weed Manual, to provide Australian vegetable growers with best practice weed management information, collated in one place. A key component of the larger Manual was translated into Vietnamese, Chinese and Khmer to ensure access to IWM resources in non-English speaking vegetable growing communities. Comprehensive IWM guidelines were published specific for the 11 priority weed species. Detailed farm case studies were completed to illustrate effective pathways to weed seed bank reduction using contrasting approaches. These materials as well as their key principles were promoted via industry communication channels and social media, and provide a lasting legacy of information to the vegetable industry.</p>