herbicide resistance

The objective of this study was to determine whether a junglerice population from the tropical Ord River region of northwest Australia was glyphosate resistant, and whether alternative herbicides labeled for junglerice control were still effective.

Pyroxasulfone is a new pre-emergence herbicide that provides effective control of Lolium rigidum, including populations with evolved resistance to multiple herbicide modes of action.

The interaction between environment and genetic traits under selection is the basis of evolution. In this study, we have investigated the genetic basis of herbicide resistance in a highly characterized initially herbicide-susceptible Lolium rigidum population recurrently selected with low (below recommended label) doses of the herbicide diclofop-methyl.

Plants can rapidly evolve resistance to herbicide in response to repeated selection. This study focuses on cross-resistance patterns observed in Lolium rigidum following pyroxasulfone recurrent selection.

Avena spp. are world weeds with many cases of evolved herbicide resistance. In Australia, Avena spp. (wild oat and sterile oat) are a major problem, especially in grain crops. Acetyl-CoA carboxylase (ACCase)–inhibiting herbicides have been used extensively since the late 1970s for Avena spp. control.

The widespread evolution of resistance in rigid ryegrass populations to the highly effective, in-crop, selective herbicides used within southern Australian grain-crop production systems has severely diminished the available herbicide resource.

This study investigated a possible link between seed dormancy and herbicide resistance status of Lolium rigidum (annual or rigid ryegrass). Mature seeds were collected from 406 populations across the 14-million hectare grain belt of southern Western Australia.

The dynamics of herbicide resistance evolution in plants are influenced by many factors, especially the biochemical and genetic basis of resistance. Herbicide resistance can be endowed by enhanced rates of herbicide metabolism because of the activity of cytochrome P450 enzymes, although in weedy plants the genetic control of cytochrome P450-endowed herbicide resistance is poorly understood.

This is the first report of low-dose glyphosate selection causing a shift towards paraquat resistance. Herbicide resistance in weed species is a serious threat to world agriculture. We report rapid resistance evolution in the genetically variable cross-pollinated grass weed Lolium rigidum when recurrently selected with low doses.

Twenty-two amino acid substitutions at seven conserved amino acid residues in the acetohydroxyacid synthase (AHAS) gene have been identified to date that confer target-site resistance to AHAS-inhibiting herbicides in biotypes of field-evolved resistant weed species.