Publications

With glyphosate currently under intense scrutiny worldwide from an environmental and health perspective, the paper’s authors contemplate possible scenarios of farming without our most important and popular herbicide.

This paper reviews the literature to understand the effects of glyphosate resistance on plant fitness at the molecular, biochemical and physiological levels. A number of correlations between enzyme characteristics and glyphosate resistance imply the existence of a plant fitness cost associated with resistance-conferring mutations in the glyphosate target enzyme, 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS). These biochemical changes result in a tradeoff between the glyphosate resistance of the EPSPS enzyme and its catalytic activity.

The objective of this study was to determine whether a jungle rice population from the tropical Ord River region of northwest Australia was glyphosate-resistant and whether alternative herbicides labelled for jungle rice control were still effective. Seed samples collected from the field site were initially screened with glyphosate in the glasshouse, and surviving individuals were self-pollinated for subsequent glyphosate dose-response studies. Glyphosate resistance was confirmed, as the suspected resistant population was found to be 8.6-fold more resistant to glyphosate than a susceptible population-based on survival (LD50 of 3.72 kg ha21), and 5.6-fold more resistant based on biomass reduction (GR50 of 1.16 kg ha21).

In this Plant Physiology paper, it is clearly established that glyphosate resistance in this Echinochloa population is due to an enhanced capacity to metabolise glyphosate, catalysed by an Aldo-keto reductase gene. The first author on the paper is Dr Pan Lang, now at the Hunan Agricultural University, Changsha, China.

Pre-emergent herbicides play an important role in conservation agriculture, however, crop residues on the soil surface in these systems can intercept a considerable amount of herbicide during application. Cutting crops relatively high at harvest has some advantages, such as allowing faster harvest, and this also means that there is less horizontal residue on the soil surface. This field study tested the impact of standing wheat residue height and amount of horizontal residue on the interception, leaching and weed-control efficacy of the pre-emergent herbicide pyroxasulfone in the 2015 and 2016 growing seasons.

Resistance to the auxinic herbicides 2,4-D and dicamba is widespread in Western Australian R. raphanistrum populations, with the resistance mechanism appearing to involve alterations in the physiological response to synthetic auxins and in plant defense. This study aimed to determine whether these alterations cause inhibition in plant growth or reproduction that could potentially be exploited to manage 2,4-D–resistant populations in cropping areas.