Varying responses of field-selected herbicide-resistant rigid ryegrass (Lolium rigidum) populations to combinations of phorate with PPI herbicides

Weed Science ◽  
2020 ◽  
Vol 68 (4) ◽  
pp. 367-372
Author(s):  
David J. Brunton ◽  
Peter Boutsalis ◽  
Gurjeet Gill ◽  
Christopher Preston
Keyword(s):  
Fold Increase ◽  
Acid Synthesis ◽  
Resistance Mechanisms ◽  
Lolium Rigidum ◽  
Cytochrome P450 Enzymes ◽  
Long Chain Fatty Acid ◽  
Herbicide Resistant ◽  
Rigid Ryegrass ◽  
Sites Of Action

AbstractOrganophosphate insecticides, which have the capacity to inhibit specific herbicide-degrading (cytochrome P450) enzymes, have been used to explore metabolic herbicide-resistance mechanisms in weeds. This study investigates the response of seven field-selected rigid ryegrass (Lolium rigidum Gaudin) populations to herbicides from three different sites of action in the presence or absence of the P450 inhibitor phorate. Phorate antagonized the thiocarbamate herbicides triallate and prosulfocarb (8-fold increase in LD50) in multiple resistant L. rigidum populations with resistance to three different site-of-action herbicides. In contrast, phorate synergized trifluralin and propyzamide in some populations, reducing the LD50 by 50%. Conversely, treatment with phorate had no significant effect on the LD50 for S-metolachlor or pyroxasulfone (inhibitors of very-long-chain fatty-acid synthesis). Phorate has diverse effects that are herbicide and population dependant in field-selected L. rigidum, suggesting P450 involvement in the metabolism of trifluralin and failure to activate thiocarbamate herbicides in these populations. This research highlights the need for implementation of diverse approaches other than herbicide alone as part of a long-term integrated strategy to reduce the likelihood of metabolism-based resistance to PPI herbicides in L. rigidum.

Herbicide Application Strategies for the Control of Rigid Ryegrass (Lolium rigidum) in Wide-Row Faba Bean (Vicia faba) in Southern Australia

2012 ◽  
Vol 26 (2) ◽  
pp. 284-288 ◽  
Author(s):  
Samuel G. L. Kleemann ◽  
Gurjeet S. Gill
Keyword(s):  
Faba Bean ◽  
Field Experiments ◽  
Control Strategies ◽  
South Australia ◽  
Yield Reduction ◽  
Lolium Rigidum ◽  
Herbicide Application ◽  
Spike Density ◽  
Herbicide Resistant ◽  
Rigid Ryegrass

Two field experiments were undertaken at Roseworthy, South Australia from 2006 to 2007 to evaluate the performance of herbicide application strategies for the control of herbicide-resistant rigid ryegrass in faba bean grown in wide rows (WR). The standard farmer practice of applying postsowing PRE (PSPE) simazine followed by POST clethodim to faba bean grown in WR provided consistent and high levels of rigid ryegrass control (≥ 96%) and caused a large reduction (P < 0.05) in spike production (≤ 20 spikes m−2) as compared with nontreated control (560 to 722 spikes m−2). Furthermore, this herbicide combination resulted in greatest yield benefits for WR faba bean (723 to 1,046 kg ha−1). Although PSPE propyzamide used in combination with shielded interrow applications of glyphosate or paraquat provided high levels of rigid ryegrass control (≥ 93%), these treatments were unable to reduce ryegrass spike density within the crop row (20 to 54 spikes m−2) to levels acceptable for continued cropping. Furthermore, a yield reduction (13 to 29%) was observed for faba bean in treatments with shielded application of nonselective herbicides and could be related to spray drift onto lower leaves. These findings highlight that shielded interrow spraying in WR faba bean could play an important role in the management of rigid ryegrass in southern Australia. However, timing of shielded interrow applications on weed control, crop safety, and issues concerning integration with more effective early-season control strategies require attention.

Weed Control and Selectivity of Pethoxamid Alone and in Mixture as a Delayed Preemergence Application to Rice

2018 ◽  
Vol 32 (5) ◽  
pp. 537-543
Author(s):  
John Godwin ◽  
Jason K. Norsworthy ◽  
Robert C. Scott
Keyword(s):  
Weed Control ◽  
Herbicide Resistance ◽  
Field Trials ◽  
Shoot Density ◽  
Red Rice ◽  
Weed Species ◽  
Viable Option ◽  
Long Chain Fatty Acid ◽  
Herbicide Resistant ◽  
Sites Of Action

AbstractThe evolution of herbicide resistance is making it extremely difficult for US rice producers to use chemical control on weed species such as barnyardgrass and red rice. To combat herbicide resistance, it is imperative that alternative herbicide sites of action (SOAs) be incorporated into rice whenever possible. There are currently no very-long-chain fatty acid–inhibiting herbicides (WSSA Group 15) labeled for use in US rice; however, pethoxamid is one such herbicide currently under development. If appropriate rice tolerance and weed control can be established, pethoxamid would represent a unique herbicide SOA for use in US rice. We conducted field trials near Stuttgart, AR, in 2015 and near Colt and Lonoke, AR, in 2016 to assess selectivity of pethoxamid and weed control alone and in combination with other herbicides as a delayed preemergence (DPRE) application in drill-seeded rice. Pethoxamid was applied at 0, 420, or 560 g ai ha–1 alone and in combination with clomazone, imazethapyr, pendimethalin, and quinclorac. Minimal rice injury occurred with any treatment assessed. A reduction in rice shoot density and plant height compared to the nontreated control followed the use of pethoxamid; however, no decrease in yield resulted. The highest levels of barnyardgrass control followed the use of imazethapyr at 91% and quinclorac at 89% regardless of the presence of pethoxamid near Lonoke; however, pethoxamid applied at both rates in combination with clomazone and quinclorac increased barnyardgrass control compared to clomazone and quinclorac applied alone. Near Colt, barnyardgrass control of 92% and 96% resulted from pethoxamid alone, averaged over the high and low rates. Based on these data, rice can tolerate pethoxamid when applied DPRE, and adequate levels of barnyardgrass control can be achieved at the rates evaluated within a program; hence, pethoxamid appears to be a viable option for use in rice to allow for increased rotation of herbicide SOAs to combat herbicide-resistant and difficult-to-control weeds.

Influence of Crop Competition and Harvest Weed Seed Control on Rigid Ryegrass (Lolium rigidum) Seed Retention Height in Wheat Crop Canopies

Weed Science ◽  
2018 ◽  
Vol 66 (5) ◽  
pp. 627-633 ◽  
Author(s):  
Michael J. Walsh ◽  
John C. Broster ◽  
Charlotte Aves ◽  
Stephen B. Powles
Keyword(s):  
Wheat Crop ◽  
Average Height ◽  
Crop Canopy ◽  
Lolium Rigidum ◽  
Weed Seed ◽  
Seed Retention ◽  
Rigid Ryegrass ◽  
Crop Maturity ◽  
Crop Competition

AbstractHarvest weed seed control (HWSC) is an Australian innovation, developed to target high proportions of weed seed retained at crop maturity by many major weed species. There is the potential, however, that a reduction in the average height of retained seed is an adaptation to the long-term use of HWSC practices. With the aim of examining the distribution of rigid ryegrass (Lolium rigidumGaudin) seed through crop canopies, a survey of Australian wheat (Triticum aestivumL.) fields was conducted at crop maturity. Nine sites with medium to long-term HWSC use were specifically included to examine the influence of HWSC use on seed retention height. During the 2013 wheat harvest,L. rigidumand wheat plant samples were collected at five heights downward through the crop canopy (40, 30, 20, 10, and 0 cm above ground level) in 71 wheat fields. Increased crop competition resulted in higher proportions ofL. rigidumseed in the upper crop canopy (>40 cm). The increase in plant height is likely a shade-intolerance response ofL. rigidumplants attempting to capture more light. This plant attribute creates the opportunity to use crop competition to improve HWSC efficacy by increasing the average height of seed retention. Crop competition can, therefore, have a double impact by reducing overallL. rigidumseed production and increasing seed retention height. Examining the distribution of wheat biomass andL. rigidumseed through the crop canopy, we determined that reducing harvest height for HWSC considerably increased the collection ofL. rigidumseed (25%) but to a lesser extent wheat crop biomass (14%). Comparison of + and − HWSC use at nine locations found no evidence of adaptation to this form of weed control following 5 to 10 yr of use. Although the potential for resistance to HWSC remains, these results indicate that this will not readily occur in the field.

Incidence of Herbicide Resistance in Rigid Ryegrass (Lolium rigidum) across Southeastern Australia

2012 ◽  
Vol 26 (3) ◽  
pp. 391-398 ◽  
Author(s):  
Peter Boutsalis ◽  
Gurjeet S. Gill ◽  
Christopher Preston
Keyword(s):  
Herbicide Resistance ◽  
South Australia ◽  
Acetolactate Synthase ◽  
Lolium Rigidum ◽  
Acetyl Coenzyme A ◽  
Main Method ◽  
Herbicide Resistant ◽  
Southeastern Australia ◽  
High Incidence ◽  
Rigid Ryegrass

Herbicide resistance in rigid ryegrass is an escalating problem in grain-cropping fields of southeastern Australia due to increased reliance on herbicides as the main method for weed control. Weed surveys were conducted between 1998 and 2009 to identify the extent of herbicide-resistant rigid ryegrass across this region to dinitroaniline, and acetolactate synthase- and acetyl coenzyme A (CoA) carboxylase-inhibiting herbicides. Rigid ryegrass was collected from cropped fields chosen at random. Outdoor pot studies were conducted during the normal winter growing season for rigid ryegrass with PRE-applied trifluralin and POST-applied diclofop-methyl, chlorsulfuron, tralkoxydim, pinoxaden, and clethodim. Herbicide resistance to trifluralin in rigid ryegrass was identified in one-third of the fields surveyed from South Australia, whereas less than 5% of fields in Victoria exhibited resistance. In contrast, resistance to chlorsulfuron was detected in at least half of the cropped fields across southeastern Australia. Resistance to the cereal-selective aryloxyphenoxypropionate-inhibiting herbicides diclofop-methyl, tralkoxydim, and pinoxaden ranged between 30 and 60% in most regions, whereas in marginal cropping areas less than 12% of fields exhibited resistance. Resistance to clethodim varied between 0 and 61%. Higher levels of resistance to clethodim were identified in the more intensively cropped, higher-rainfall districts where pulse and canola crops are common. These weed surveys demonstrated that a high incidence of resistance to most tested herbicides was present in rigid ryegrass from cropped fields in southeastern Australia, which presents a major challenge for crop producers.

Resistance to bixlozone and clomazone in cross-resistant rigid ryegrass (Lolium rigidum) populations from southern Australia

Weed Science ◽  
2021 ◽  
pp. 1-6
Author(s):  
David J. Brunton ◽  
Gurjeet Gill ◽  
Christopher Preston
Keyword(s):  
Recurrent Selection ◽  
Selection Process ◽  
Resistance Mechanism ◽  
Fold Increase ◽  
Elevated Risk ◽  
Cross Resistance ◽  
Lolium Rigidum ◽  
Rigid Ryegrass

Abstract Three resistant (R) rigid ryegrass (Lolium rigidum Gaudin) populations from southern Australia (EP162, 375-14, and 198-15) with cross-resistance to thiocarbamate, chloroacetamide, and sulfonylisoxazoline herbicides displayed reduced sensitivity to the isoxazolidinone herbicides bixlozone and clomazone. Each of these R populations was exposed to two cycles of recurrent selection (RS) in which plants were treated with the field rate of bixlozone, survivors were bulk crossed, and seed was collected. After the first cycle of recurrent selection (RS1), the LD50 to bixlozone in population 198-15 increased to 17.5-fold compared with the S population and increased further to 26.9-fold after a second cycle of recurrent selection (RS2). The recurrent selection process also increased the level of resistance to bixlozone in populations EP162 and 375-14 (7.8- to 18.4-fold) compared with the S population. Phorate antagonized bixlozone and clomazone in SLR4 (34.6- and 28.1-fold increase in LD50) and both herbicides in populations EP162 (36.5- to 46.6-fold), 375-14 (71.4- to 73.9-fold), and 198-15 (86.4- to 91.5-fold) compared with the absence of phorate. The increase in LD50 of all L. rigidum RS populations when treated with phorate suggests a lack of herbicide activation is not the likely resistance mechanism to these herbicides. This research highlights the elevated risk of thiocarbamate-resistant L. rigidum populations to rapidly evolve resistance to the isoxazolidinone herbicides bixlozone and clomazone.

Confirmation of a Three-Way (Glyphosate, ALS, and Atrazine) Herbicide-Resistant Population of Palmer Amaranth (Amaranthus palmeri) in Michigan

Weed Science ◽  
2017 ◽  
Vol 65 (3) ◽  
pp. 327-338 ◽  
Author(s):  
Jonathon R. Kohrt ◽  
Christy L. Sprague ◽  
Satya Swathi Nadakuduti ◽  
David Douches
Keyword(s):  
Copy Number ◽  
Laboratory Experiments ◽  
Fold Increase ◽  
Field Studies ◽  
Palmer Amaranth ◽  
Target Site ◽  
Susceptible Population ◽  
Herbicide Resistant ◽  
Sites Of Action ◽  
Als Inhibitor

The failure of PRE and POST applications of atrazine to control Palmer amaranth in recent field studies prompted further investigation to determine whether this population had evolved resistance to multiple herbicide sites of action, including glyphosate (Group 9), thifensulfuron (Group 2), and atrazine (Group 5). Greenhouse and laboratory experiments were conducted to: (1) confirm the presence of resistance to glyphosate, an ALS inhibitor (thifensulfuron), and atrazine in a single Palmer amaranth population; and (2) establish the molecular basis for resistance to these herbicide sites of action. In the greenhouse, glyphosate+thifensulfuron+atrazine at 1.26 kg ae ha−1+0.0044 kg ai ha−1+1.12 kg ai ha−1provided 55% control of the suspected multiply resistant (MR) Palmer amaranth population and 93% control of the known susceptible population (S). The decreased sensitivity of the MR population compared with the S population at labeled use rates of these herbicides indicated that this population was likely resistant to three different herbicide site of action groups. The RF values for POST applications of glyphosate, thifensulfuron, and atrazine were 12.2, 42.9, and 9.3 times, respectively, for the MR Palmer amaranth population relative to the S population. The RF value for atrazine PRE for the MR population was 112.2 times. Laboratory experiments confirmed that the mechanisms for resistance to ALS-inhibiting herbicides and glyphosate in the MR Palmer amaranth population were target-site based, via amino acid substitution and amplifiedEPSPScopy number, respectively. There was a Pro to Leu substitution at site 197 in the ALS inhibitor–resistant plants, and there was a greater than 50-fold increase inEPSPScopy number in the glyphosate-resistant plants. There were no nucleotide changes in thepsbAgene; therefore, atrazine resistance in this population was not target-site mediated. The evolution of this multiple herbicide-resistant Palmer amaranth population poses significant management challenges to Michigan farmers.

Germination, Growth, and Development of Herbicide Resistant and Susceptible Populations of Rigid Ryegrass (Lolium rigidum)

Weed Science ◽  
1996 ◽  
Vol 44 (2) ◽  
pp. 252-256 ◽  
Author(s):  
Gurjeet S. Gill ◽  
Roger D. Cousens ◽  
Margaret R. Allan
Keyword(s):  
Growth Rate ◽  
Growth And Development ◽  
Seedling Emergence ◽  
Lolium Rigidum ◽  
Relative Growth ◽  
Herbicide Resistant ◽  
Biological Attributes ◽  
The One ◽  
Rigid Ryegrass ◽  
Susceptible Populations

Rate of seedling emergence, relative growth rate (RGR), and phenological development were compared in several accessions of rigid ryegrass belonging to three distinct resistance classes. The aryloxyphenoxypropionate resistant (AOPP-R) class had a faster and less variable seedling emergence than the sulfonylurea resistant (SU-R) and susceptible (S) classes. However, even the fastest of the AOPP-R accessions was within the range of the S and SU-R classes. No significant differences were detected among the resistant classes in seed dormancy, RGR, and the rate of phenological development. The rate of spike emergence, irrespective of the resistance class, was related to the latitude of the origin of the accessions, suggesting adaptation to the local climates since introduction. Due to considerable variation among weed populations for most biological attributes, the need to include several R and S accessions, in studies similar to the one reported here, is of vital importance. Because of the means and variances of the three resistance classes, at least four accessions from each resistance class would have been required to detect the observed differences between emergence rates of the AOPP-R and S classes with a confidence of 95%.

Rigid Ryegrass (Lolium rigidum) Populations Containing a Target Site Mutation in EPSPS and Reduced Glyphosate Translocation Are More Resistant to Glyphosate

Weed Science ◽  
2012 ◽  
Vol 60 (3) ◽  
pp. 474-479 ◽  
Author(s):  
Yazid Bostamam ◽  
Jenna M. Malone ◽  
Fleur C. Dolman ◽  
Peter Boutsalis ◽  
Christopher Preston
Keyword(s):  
Weed Control ◽  
Glyphosate Resistance ◽  
Resistance Mechanisms ◽  
Target Site ◽  
Lolium Rigidum ◽  
Site Mutation ◽  
Susceptible Population ◽  
Intensive Use ◽  
Rigid Ryegrass ◽  
Two Populations

Glyphosate is widely used for weed control in the grape growing industry in southern Australia. The intensive use of glyphosate in this industry has resulted in the evolution of glyphosate resistance in rigid ryegrass. Two populations of rigid ryegrass from vineyards, SLR80 and SLR88, had 6- to 11-fold resistance to glyphosate in dose-response studies. These resistance levels were higher than two previously well-characterized glyphosate-resistant populations of rigid ryegrass (SLR77 and NLR70), containing a modified target site or reduced translocation, respectively. Populations SLR80 and SLR88 accumulated less glyphosate, 12 and 17% of absorbed glyphosate, in the shoot in the resistant populations compared with 26% in the susceptible population. In addition, a mutation within the target enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) where Pro106had been substituted by either serine or threonine was identified. These two populations are more highly resistant to glyphosate as a consequence of expressing two different resistance mechanisms concurrently.

Chloroacetamide Resistance in Rigid Ryegrass (Lolium rigidum)

Weed Science ◽  
1994 ◽  
Vol 42 (2) ◽  
pp. 153-157 ◽  
Author(s):  
Michael W. M. Burnet ◽  
Andrew R. Barr ◽  
Stephen B. Powles
Keyword(s):  
Avena Sativa ◽  
High Probability ◽  
Cross Resistance ◽  
Lolium Rigidum ◽  
Germination Test ◽  
Herbicide Resistant ◽  
Relative Response ◽  
Germination Medium ◽  
Rigid Ryegrass

Metolachlor has been evaluated both as a herbicide for use in cultivated oats (Avena sativaL.) and for its potential as an alternative herbicide for the control of herbicide-resistant rigid ryegrass. Eight herbicide-resistant and two susceptible biotypes of rigid ryegrass were tested for their susceptibility to metolachlor. Response to metolachlor was determined both in soil and an agar germination medium. The LD50for metolachlor in agar for a susceptible biotype (VLR1) was 0.13 μM. Five biotypes, SLR5 (6.9 fold), SLR31 (5.2 fold), SLR10 (2.5 fold), NLR12 (2.1 fold) and VLR69 (1.9 fold), were cross-resistant to metolachlor when compared with VLR1. Relative response of the biotypes was similar in both soil and agar, validating the use of an agar germination test to determine the susceptibility of rigid ryegrass biotypes to metolachlor. Biotypes cross-resistant to metolachlor also were cross-resistant to alachlor (SLR5 6.7 fold, SLR31 5.9 fold, SLR10 2.4 fold, and VLR69 1.6 fold with the LD50for VLR1 being 0.49 μM) and propachlor (SLR57.2 fold, SLR31 7.2 fold, SLR10 3.0 fold and VLR69 2.5 fold with the LD50for VLR1 being 0.47 μM) indicating that cross-resistance extends to other members of the chloroacetamide group. Cross-resistance to chloroacetamides was observed in biotypes that previously had been reported as cross-resistant to other herbicides. In contrast, biotypes with limited herbicide histories were generally not cross-resistant to metolachlor. These results indicate that there is a high probability of chloroacetamide cross-resistance in populations of herbicide-resistant rigid ryegrass.

scholarly journals Long-term intake of soyabean phytosterols lowers serum TAG and NEFA concentrations, increases bile acid synthesis and protects against fatty liver development in dyslipidaemic hamsters

2014 ◽  
Vol 112 (5) ◽  
pp. 663-673 ◽  
Author(s):  
Sirle Laos ◽  
Antoni Caimari ◽  
Anna Crescenti ◽  
Jamileh Lakkis ◽  
Francesc Puiggròs ◽  
...  
Keyword(s):  
Bile Acid ◽  
Fatty Liver ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Plasma Cholesterol ◽  
Fold Increase ◽  
Acid Synthesis ◽  
Acid Oxidation ◽  
Standard Diet ◽  
Cholesterol Ratio

Various human trials and pre-clinical studies have suggested that dietary plant sterols possess hypotriacylglycerolaemic properties apart from their cholesterol-lowering properties. We hypothesised that phytosterols (PS) might attenuate triacylglycerolaemia by interfering with the deleterious effects of cholesterol overload in the liver. In the present study, twenty hamsters (Mesocricetus auratus) with diet-induced combined hyperlipidaemia were fed a high-fat diet (HFD, n 10) or a HFD supplemented with soyabean PS (n 10) for 40 d. In parallel, a healthy group was fed a standard diet (n 10). PS normalised fasting plasma cholesterol concentrations completely after 20 d and were also able to normalise serum TAG and NEFA concentrations after 40 d. HFD feeding caused microvesicular steatosis and impaired the expression of key genes related to fatty acid oxidation such as PPARA, carnitine palmitoyltransferase-Iα (CPT1A) and phosphoenolpyruvate carboxykinase 1 (PCK1) in the liver. PS treatment completely protected against HFD-induced steatosis and resulted in a normalised hepatic gene expression profile. The protection of the hepatic function by PS was paralleled by increased faecal cholesterol excretion along with a 2-fold increase in the biliary bile acid (BA):cholesterol ratio. The present study supports the conclusion that long-term consumption of PS can reduce serum TAG and NEFA concentrations and can protect against the development of fatty liver via different mechanisms, including the enhancement of BA synthesis. The results of the present study place these compounds as promising hepatoprotective agents against fatty liver and its derived pathologies.

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