In Australia, the development of multiple herbicide resistance in some of the most serious annual weeds has been the catalyst for the development of new agronomic practices. Researchers and industry have developed new non-chemical weed control techniques focused on weed seed capture and destruction during commercial grain crop harvest.
The biggest problem weeds infesting Australian cropping fields are annual ryegrass, wild radish, wild oats and brome grass. Walsh explains that these annual species all have high genetic diversity, boast prolific seed production, can establish high population densities and have relatively short-lived seed banks. They also retain a significant portion of their seeds at maturity, meaning that many seeds remain attached to the upright plant and are collected during the grain crop harvest. Walsh and his colleagues have developed alternative weed control strategies or harvest weed seed control (HWSC) systems used during commercial grain harvest operations to minimize fresh seed inputs to the seedbank and lower overall weed populations.
“Restricting weed population densities to very low levels also reduces the potential for resistance evolution to our remaining highly valued herbicide resources,” he adds. “Herbicide preservation is essential for sustaining future crop production so the addition of HWSC and other control strategies is absolutely necessary in supporting the ongoing efficacy of herbicides.”