Preventing glyphosate resistance in weeds of the northern grain region

Abstract

Herbicide resistance is an increasing challenge across Australia's northern grain belt. Already 10 weeds have been confirmed as herbicide resistant in various parts of this region, and more have been identified at risk of developing resistance, particularly to glyphosate. Apart from common sow-thistle (Sonchus oleraceus) and summer grasses, the weed threats differ across the region along with the farming systems. Mostly, summer weeds are at risk in central Queensland, whereas a mix of summer and winter weeds are at risk in southern Queensland and northern New South Wales. The risk is greatest for the cropping systems using zero tillage with only limited rotation between summer and winter crops. Preventive strategies are being tested currently in a series of long-term field experiments in this diverse cropping region. The proposed strategies to conserve glyphosate susceptibility use alternatives to glyphosate and/or stopping seed set for each weed flush during one in 4-5 seasons. These strategies will help ensure maximum effective life of important herbicides, as well as ensuring the continuing viability of conservation cropping in this region.