Herbicide resistance in lucerne seed production systems in the south east regions of South Australia

Lucerne Australia Inc.

  • Project code: PRO-015003

  • Project stage: Closed

  • Project start date: Friday, October 8, 2021

  • Project completion date: Wednesday, June 21, 2023

  • National Priority: PSE-Sustainable certified temperate pasture seed production


Lucerne is an important pasture species in Australia. Over 80% of the lucerne seed produced in Australia is grown in the south east region of South Australia. It is critical to manage weeds effectively in seed crops to meet seed certification requirements and an integral part of weed control in lucerne is the use of herbicides.

Dependence on a few herbicides increases the risk of herbicide resistance in weeds. There is anecdotal evidence of poor weed control in both seedling and established lucerne stands in the Keith region following herbicide applications. There are also reports of weed control failure on channels and check-banks, with subsequent migration of weeds from these areas into production areas.

Lucerne Australia will engage Plant Science Consulting to conduct a weed survey of commercial production areas in the main lucerne seed producing area of Australia. The purpose of this survey is to collect seeds and generate data on the current level of herbicide resistance in annual ryegrass, barley grass and sowthistle populations.

This survey results will inform the development of specific integrated weed management guidelines for the lucerne seed industry to extend the life of important herbicides. There is a requirement of farmers across all industries to carefully manage the herbicide options they have over time. The benefit of this research will be to inform the industry of the extent of resistance, and help farmers and advisers take a longer-term resistance risk view thus improving the profitability and sustainability of the Australian Lucerne Seed Industry.


Pasture Seeds

Research Organisation

Lucerne Australia Inc.

Objective Summary

The purpose of this research is to generate and communicate information on the extent of resistance in three key weeds of importance to commonly used herbicide groups in lucerne seed crops in the SE of South Australia. The outcome will be increased understanding and awareness of herbicide resistance within the industry and the development of integrated weed management (IWM) strategies to manage the risk.


The objectives are:

  • To conduct a weed survey to collect seeds from annual ryegrass (Lolium rigidum), barley grass (Hordeum glaucum and H. leporinum) and sowthistle (Sonchus oleraceus) in commercial lucerne production areas.
  • To conduct herbicide resistance testing of the three key weeds surveyed to commonly used herbicides.
  • To provide Lucerne Australia with information on the extent of herbicide resistance in these weeds to assist in the development of IWM strategies specific to the lucerne seed industry.