Widespread occurrence of multiple herbicide resistance in Western Australian annual ryegrass (Lolium rigidum) populations

Abstract

In 2003, a random survey was conducted across the Western Australian wheatbelt to establish the frequency and distribution of herbicide resistance in ryegrass populations infesting crop fields. Five hundred cropping fields were visited at crop maturity, and ryegrass seed was collected in 452 of these fields. Subsequently, each crop field population was screened with herbicides of various modes of action that are commonly used for ryegrass control in Australian cropping systems. Most of these ryegrass populations were found to be resistant to the ACCase-inhibitor herbicide diclofop-methyl (68%) and the ALS-inhibitor herbicide sulfometuron (88%). A comparison of resistance levels in the same agronomic zones surveyed 5 years earlier determined that there had been an increase of 20 percentage points in the frequency of resistance over this 5-year period. This survey also determined that the majority (64%) of populations were found to be multiple resistant to both diclofop-methyl and sulfometuron. The distribution patterns of the collected populations indicated that there were higher frequencies of resistant and developing resistance populations occurring in the intensively cropped regions of the wheatbelt, which had greater herbicide selection pressure. Of concern is that 24% and 8% of populations were found to be developing resistance to trifluralin and clethodim, respectively. Currently these herbicides are heavily relied upon for control of ACCase and ALS herbicide resistant ryegrass. Nearly all populations remain susceptible to glyphosate. Ryegrass across the WA wheatbelt now exhibits multiple resistance across many but not all herbicides, posing severe management and sustainability challenges.

Diversity of Acetyl-Coenzyme A Carboxylase Mutations in Resistant Lolium Populations: Evaluation Using Clethodim

“…Several Lolium rigidum populations resistant to clethodim were identified during herbicide screening in a large random survey across the western Australian wheat (Triticum aestivum) belt (Owen et al, 2007). Seedlings of these field populations were sprayed with clethodim at the commercial rate of 60 g ha 21 using a cabinet sprayer delivering 113 L ha 21 water at a pressure of 200 kPa.…”

“…Five years later, however, our random survey of 452 ryegrass populations from the same region revealed clethodim resistance to be present in 8% of these populations (Owen et al, 2007). Thus far, the Asp-2078-Gly mutation in the plastidic ACCase enzyme is the only known mutation endowing clethodim resistance (Délye et al, 2005).…”

“…Within a few years of initial ACCase herbicide use (1978), the first ACCase herbicide-resistant L. rigidum population was evident (Heap and Knight, 1986). Since then, ACCase herbicide-resistant L. rigidum populations have evolved across huge areas of Australian croplands (Llewellyn and Powles, 2001;Owen et al, 2007). The biochemical basis of ACCase herbicide resistance has been revealed in several populations to involve resistant ACCase (Matthews et al, 1990;Holtum et al, 1991;Tardif et al, 1993Tardif et al, , 1996.…”

Evaluation of Fenoxaprop-P-Ethyl Resistant Littleseed Canarygrass (Phalaris minor) in Pakistan

“…However, the level of resistance was different for each biotype. The prolonged use of the same herbicide imposes the selection pressure on weeds to increase the widespread of resistant biotypes (Owen et al, 2007). Phlaris minor resistance to fenoxaprop-P-ethyl and other ACCase inhibitors have been reported in different countries worldwide including India, Iran, Mexico, South Africa, United States and Australia (Heap, 2015).…”

Bioensaios de atividade alelopática dos esteroides espinasterol, espinasterona e glicopiranosil espinasterol

“…As formas atuais de controle de plantas daninhas, como roçagem (Chiovato et al, 2007;Tipping, 2008), queimadas (Durigan et al, 2007) e utilização de herbicidas sintéticos (Duke et al, 2007), não estão atendendo às atuais necessidades da sociedade, devido às agressões aos recursos naturais (água e solo), à vida silvestre e aos alimentos dos animais e das pessoas, além de favorecer o aumento sistemático no número de espécies de plantas daninhas resistentes aos atuais produtos no mundo (Owen et al, 2007;Powles & Yu, 2010;Gressel, 2011;Riar et al, 2011). Somada a esses fatores ainda existe a busca dos produtores por herbicidas que possam proporcionar maior produtividade, lucratividade e redução nos gastos com estes produtos.…”