Weed Resistance Monitoring in the Canadian Prairies

2008 ◽  
Vol 22 (3) ◽  
pp. 530-543 ◽  
Author(s):  
Hugh J. Beckie ◽  
Julia Y. Leeson ◽  
A. Gordon Thomas ◽  
Clark A. Brenzil ◽  
Linda M. Hall ◽  
...  
Keyword(s):  
Acetolactate Synthase ◽  
Resistance Testing ◽  
Cross Resistance ◽  
Northern Great Plains ◽  
Wild Oat ◽  
Resistance Monitoring ◽  
Green Foxtail ◽  
Group 2 ◽  
Weed Resistance ◽  
Group 1

Weed resistance monitoring has been routinely conducted in the Northern Great Plains of Canada (Prairies) since the mid-1990s. Most recently, random surveys were conducted in Alberta in 2001, Manitoba in 2002, and Saskatchewan in 2003 totaling nearly 800 fields. In addition, nearly 1,300 weed seed samples were submitted by growers across the Prairies between 1996 and 2006 for resistance testing. Collected or submitted samples were screened for group 1 [acetyl-CoA carboxylase (ACCase) inhibitor] and/or group 2 [acetolactate synthase (ALS) inhibitor] resistance. Twenty percent of 565 sampled fields had an herbicide-resistant (HR) wild oat biotype. Most populations exhibited broad cross-resistance across various classes of group 1 or group 2 herbicides. In Manitoba, 22% of 59 fields had group 1–HR green foxtail. Group 2–HR biotypes of kochia were documented in Saskatchewan, common chickweed and spiny sowthistle in Alberta, and green foxtail and redroot pigweed in Manitoba. Across the Prairies, HR weeds are estimated to occur in fields covering an area of nearly 5 million ha. Of 1,067 wild oat seed samples submitted by growers and industry for testing between 1996 and 2006, 725 were group 1 HR, 34 group 2 HR, and 55 groups 1 and 2 HR. Of 80 submitted green foxtail samples, 26 were confirmed group 1 HR; most populations originated from southern Manitoba where the weed is most abundant. Similar to the field surveys, various group 2–HR biotypes were confirmed among submitted samples: kochia, wild mustard, field pennycress,Galiumspp., common chickweed, and common hempnettle. Information from grower questionnaires indicates patterns of herbicide usage are related to location, changing with cropping system. Two herbicide modes of action most prone to select resistance, groups 1 and 2, continue to be widely and repeatedly used. There is little evidence that growers are aware of the level of resistance within their fields, but a majority have adopted herbicide rotations to proactively or reactively manage HR weeds.

Herbicide-Resistant Weeds in the Canadian Prairies: 2007 to 2011

2013 ◽  
Vol 27 (1) ◽  
pp. 171-183 ◽  
Author(s):  
Hugh J. Beckie ◽  
Chris Lozinski ◽  
Scott Shirriff ◽  
Clark. A. Brenzil
Keyword(s):  
Acetolactate Synthase ◽  
Fold Increase ◽  
Wild Oat ◽  
Total Field ◽  
Herbicide Resistant ◽  
Wild Mustard ◽  
Green Foxtail ◽  
Group 2 ◽  
Field Area ◽  
Group 1

A late-summer survey of herbicide-resistant (HR) weeds was conducted in Alberta in 2007, Manitoba in 2008, and Saskatchewan in 2009, totaling 1,000 randomly selected annually cropped fields. In addition, we screened 1,091 weed seed samples (each sample from one field) submitted by Prairie growers between 2007 and 2011. Of 677 fields where wild oat samples were collected, 298 (44%) had an HR biotype. Group 1 (acetyl CoA carboxylase inhibitor)-HR wild oat was confirmed in 275 fields (41%), up from 15% in previous baseline surveys (2001 to 2003). Group 2 (acetolactate synthase)-HR wild oat was found in 12% of fields (vs. 8% in 2001 to 2003). Group 8 (triallate, difenzoquat)-HR wild oat was identified in only 8% of fields (not tested in 2001 to 2003); the frequency of occurrence of group 1+2-HR wild oat was similar (8%, vs. 3% in 2001 to 2003). Group 1-HR green foxtail was found in 27% of 209 fields sampled for the weed (vs. 6% in 2001 to 2003). Group 2-HR spiny sowthistle was confirmed in all Alberta fields sampled (vs. 67% in 2001); common chickweed was found mainly in Alberta in 40% of fields (vs. 17% in 2001). Group 2-HR weed biotypes not previously detected in the baseline surveys included false cleavers mainly in Alberta (17% of fields) and Saskatchewan (21%), Powell amaranth in Manitoba (16% of fields), wild mustard (three populations in Saskatchewan and Manitoba), and wild buckwheat (one population in Alberta). No sampled weed populations across the Prairies were found to be resistant to herbicides from group 4 (synthetic auxins), group 9 (glyphosate), or group 10 (glufosinate). Based on the proportion of total field area at each site infested with HR weeds, it is estimated that 7.7 million ha (29% of annually cropped land) are infested with HR weeds (eight-fold increase from 2001 to 2003), in a total field area of 9.9 million ha (37%)—over a two-fold increase. Of 816 cases of HR wild oat identified from submitted samples, 69% were group 1-HR, 15% group 2-HR, and 16% group 1+2-HR. Additionally, there were 10 populations of group 1-HR green foxtail in Saskatchewan or Manitoba, and six populations of group 1-HR Persian darnel in southern Alberta and Saskatchewan. Various group 2-HR broadleaf weeds were identified, including 17 wild mustard populations mainly from Saskatchewan and 39 cleavers populations across the three Prairie provinces. Herbicide-use data from 2006 to 2010 indicated continued reliance on group 1 herbicides in cereal crops and group 2 herbicides in pulse crops.

scholarly journals Herbicide resistance in the Canadian prairie provinces : Five years after the fact

2005 ◽  
Vol 75 (4) ◽  
pp. 5-16 ◽  
Author(s):  
I.N. Morrisson ◽  
M.D. Devine
Keyword(s):  
Herbicide Resistance ◽  
Effective Control ◽  
Cross Resistance ◽  
Multiple Resistance ◽  
Canadian Prairie ◽  
Wild Oats ◽  
Wild Mustard ◽  
Green Foxtail ◽  
Group 2 ◽  
Group 1

Herbicide resistance was first recognized as a problem on the Canadian Prairies in 1988 when trifluralin-resistant green foxtail (Setaria viridis) was reported in Manitoba, and chlorsulfuron-resistant chickweed (Stellaria media) and koehia (Kochia scoparia) in Alberta and Saskatchewan, respectively. Since then, the number of resistant weeds has increased to include wild oats (Avena fatua) resistant to triallate and to aryloxyphenoxypropionate and cyclohexanedione (group 1) herbicides, green foxtail to group 1 herbicides, Russian thistle (Salsola pestifer) and wild mustard (Sinapis arvensis) to sulfonylurea and imidazolinone (group 2) herbicides, and wild mustard to growth regulator (group 4) herbicides. The levels and patterns of cross-resistance to chemicals in groups 1 and 2 vary widely among different populations, with resistance factors [resistant to susceptible (R:S) ratios] derived from dose response curves typically ranging from < 2 to > 150. Group 1 resistance in green foxtail and group 2 resistance in chickweed and kochia populations are due to reduced sensitivities of the target enzymes, acetyl coenzyme-A carboxylase (ACCase) and acetolactate synthase (ALS), respectively. The mechanisms of resistance in the other species including wild oats resistant to ACCase inhibitors (group 1 ) and to triallate/difenzoquat (group 8) are unclear. At present, the only instance of multiple resistance in western Canada is green foxtail resistant to chemicals in both groups 1 and 3 (ACCase inhibitors and dinitroanilines). Future concerns focus mainly on the increasing seriousness of group 1 and 8 resistance across the Prairies, and on the possibility of selecting for multiple resistance in weeds such as green foxtail for which there are few remaining effective control options.

Nature, Occurrence, and Cost of Herbicide-Resistant Wild Oat (Avena fatua) in Small-Grain Production Areas

1999 ◽  
Vol 13 (3) ◽  
pp. 612-625 ◽  
Author(s):  
Hugh J. Beckie ◽  
A. Gordon Thomas ◽  
Anne Légère ◽  
David J. Kelner ◽  
Rene C. van Acker ◽  
...  
Keyword(s):  
Great Plains ◽  
Cropping Systems ◽  
Acetolactate Synthase ◽  
Avena Fatua ◽  
Northern Great Plains ◽  
Wild Oat ◽  
Herbicide Resistant ◽  
Multiple Group ◽  
Production Areas ◽  
Group 1

Surveys were conducted across the northern Great Plains of Canada in 1996 and 1997 to determine the nature and occurrence of herbicide-resistant (HR) biotypes of wild oat (Avena fatua). The surveys indicated that resistance to acetyl-CoA carboxylase (ACCase) inhibitors (Group 1) occurred most frequently relative to other herbicide groups. Group 1-HR wild oat occurred in over one-half of fields surveyed in each of the three prairie provinces. Of particular concern was the relatively high incidence of multiple-group resistance in wild oat in Saskatchewan and Manitoba. In Saskatchewan, 18% of Group 1-HR populations were also resistant to acetolactate synthase inhibitors (imidazolinones), even though these herbicides were not frequently used. In Manitoba, 27% of fields surveyed had wild oat resistant to herbicides from more than one group. Four populations were resistant to all herbicides registered for use in wheat (Triticum aestivum). Depending on the nature of resistance in wild oat, alternative herbicides available for their control may substantially increase costs to the grower. The cost to growers of managing HR wild oat in Saskatchewan and Manitoba using alternative herbicides is estimated at over $4 million annually. For some HR biotypes, alternative herbicides either are not available or all have the same site of action, which restricts crop or herbicide rotation options and threatens the future sustainability of small-grain annual cropping systems where these infestations occur.

scholarly journals Survey of herbicide-resistant wild oat (Avena fatua) in two townships in Saskatchewan

2002 ◽  
Vol 82 (2) ◽  
pp. 463-471 ◽  
Author(s):  
H. J. Beckie ◽  
A. G. Thomas ◽  
F. C. Stevenson
Keyword(s):  
Herbicide Resistance ◽  
Acetolactate Synthase ◽  
Avena Fatua ◽  
Farm Size ◽  
Wild Oat ◽  
Multiple Group ◽  
Group 2 ◽  
Als Inhibitors ◽  
Group Resistance ◽  
Group 1

The nature and occurrence of herbicide resistance in wild oat in annual crops grown in the Grassland and Parkland regions of Saskatchewan were determined in a systematic survey of fields in two townships in 1997. The survey found that over one-half of fields in both townships had populations resistant to Group 1 [acetyl-CoA carboxylase (ACCase) inhibitors], Group 2 [acetolactate synthase (ALS) inhibitors], and/or Group 8 (e.g., triallate, difenzoquat) herbicides. Forty-three percent of fields in the Grassland township and 48% of fields in the Parkland township had Group 1-resistant (HR) wild oat; 30 and 17% of fields in the Grassland and Parkland township, respectively, had populations exhibiting Group 2 resistance, whereas about 15% of fields in both townships had Group 8-HR wild oat. Single- (Groups 1, 2, or 8) and multiple-group resistance (1, 2; 1, 8; 2, 8; 1, 2, 8) were exhibited in populations in fields in both townships. Frequency of occurrence of resistance was not generally affected by farm size. The nature of resistance in wild oat populations is more diverse, differences in distribution and abundance of HR wild oat biotypes between Grassland and Parkland regions are generally less apparent, and occurrence of resistance is more prevalent than documented previously. Key words: Avena fatua, herbicide resistance, survey

Herbicide-resistant weeds in the Canadian prairies: 2012 to 2017

2019 ◽  
Vol 34 (3) ◽  
pp. 461-474
Author(s):  
Hugh J. Beckie ◽  
Scott W. Shirriff ◽  
Julia Y. Leeson ◽  
Linda M. Hall ◽  
K. Neil Harker ◽  
...  
Keyword(s):  
Acetolactate Synthase ◽  
Control Group ◽  
Wild Oat ◽  
Weed Species ◽  
Canadian Prairies ◽  
Herbicide Resistant ◽  
Sample Testing ◽  
Group 2 ◽  
Synthase Inhibitor ◽  
Group 1

AbstractThis report updates the incidence of herbicide-resistant (HR) weeds across western Canada from the last report covering 2007 to 2011. This third round of preharvest surveys was conducted in Saskatchewan in 2014 and 2015, Manitoba in 2016, and Alberta in 2017, totaling 798 randomly selected cropped fields across 28 million ha. In addition, we screened 1,108 weed seed samples submitted by prairie growers or industry between 2012 and 2016. Of 578 fields where wild oat seed was collected, 398 (69%) had an HR biotype: 62% acetyl-CoA carboxylase inhibitor (WSSA Group 1) resistant, 34% acetolactate synthase inhibitor (Group 2) resistant, and 27% Group 1+2 resistant (vs. 41%, 12%, and 8%, respectively, in the previous second-round surveys from 2007 to 2009). The sharp increase in Group 2 resistance is the result of reliance on this site of action to manage Group 1 resistance and the resultant increased selection pressure. There are no POST options to control Group 1+2–HR wild oat in wheat or barley. The rise of Group 2 resistance in green foxtail (11% of sampled fields) and yellow foxtail (17% of Manitoba fields), which was not detected in the previous survey round, parallels the results for wild oat resistance. Various Group 2–HR populations of broadleaf weeds were confirmed, with cleavers and field pennycress being most abundant. Results of submission-sample testing reflected survey results. Although not included in this study, a postharvest survey in Alberta in 2017 indicated widespread Groups 2, 4 (dicamba), and 9 (glyphosate) resistance in kochia and Group 2 resistance in Russian thistle. These surveys bring greater awareness of HR weeds to growers and land managers at local and regional levels, and highlight the urgency to preserve herbicide susceptibility in our key economic weed species.

Imidazolinone and Sulfonylurea Resistance in a Biotype of Common Waterhemp (Amaranthus rudis)

Weed Science ◽  
1996 ◽  
Vol 44 (4) ◽  
pp. 789-794 ◽  
Author(s):  
Sarah Taylor Lovell ◽  
Loyd M. Wax ◽  
Michael J. Horak ◽  
Dallas E. Peterson
Keyword(s):  
Acetolactate Synthase ◽  
The United States ◽  
Cross Resistance ◽  
Common Waterhemp ◽  
Whole Plant ◽  
Amaranthus Rudis ◽  
Plant Level ◽  
High Degree ◽  
Selection Agent ◽  
Weed Resistance

The incidence of weed resistance to acetolactate synthase (ALS) inhibiting herbicides has increased in the United States. In 1993, a population of ALS-resistant common waterhemp was discovered after two confirmed applications of an imidazolinone herbicide. Following another imazethapyr application in the glasshouse, the resistant biotype demonstrated 130-fold resistance to imazethapyr at the whole plant level. The concentration of imazethapyr required to inhibit the ALS activity by 50% was 520 times greater for the resistant biotype than the susceptible. Plants also demonstrated cross-resistance to the sulfonylureas, chlorimuron and thifensulfuron, at the whole plant and enzyme levels. This particular discovery is of concern due to the low number of applications of the selection agent (imazaquin 1989, imazethapyr 1992, and imazethapyr in the greenhouse) and the high degree of cross-resistance eliminating several options for weed control.

Glyphosate- and Acetolactate Synthase Inhibitor–Resistant Kochia (Kochia scoparia) in Western Canada

Weed Science ◽  
2013 ◽  
Vol 61 (2) ◽  
pp. 310-318 ◽  
Author(s):  
Hugh J. Beckie ◽  
Robert E. Blackshaw ◽  
Ryan Low ◽  
Linda M. Hall ◽  
Connie A. Sauder ◽  
...  
Keyword(s):  
Dose Response ◽  
Best Management Practices ◽  
Management Practices ◽  
Acetolactate Synthase ◽  
Glyphosate Resistance ◽  
Western Canada ◽  
Wild Oat ◽  
Green Foxtail ◽  
Inhibitor Resistance ◽  
Als Inhibitor

In summer, 2011, we investigated suspected glyphosate-resistant (GR) kochia in three chem-fallow fields (designated F1, F2, F3, each farmed by a different grower) in southern Alberta. This study characterizes glyphosate resistance in those populations, based on data from dose–response experiments. In a greenhouse experiment, the three populations exhibited a resistance factor ranging from 4 to 6 based on shoot biomass response (GR50ratios), or 5 to 7 based on survival response (LD50ratios). Similar results were found in a field dose–response experiment at Lethbridge, AB, in spring 2012 using the F2 kochia population. In fall 2011, we surveyed 46 fields within a 20-km radius of the three chem-fallow fields for GR kochia. In the greenhouse, populations were screened with glyphosate at 900 g ae ha−1. Seven populations were confirmed as GR, the farthest site located about 13 km from the three originally confirmed populations. An additional GR population more than 100 km away was later confirmed. Populations were screened for acetolactate synthase (ALS)–inhibitor (thifensulfuron : tribenuron) and dicamba resistance in the greenhouse, with molecular characterization of ALS-inhibitor resistance in the F1, F2, and F3 populations. All GR populations were resistant to the ALS-inhibiting herbicide, but susceptible to dicamba. ALS-inhibitor resistance in kochia was conferred by Pro197, Asp376, or Trp574amino acid substitutions. Based upon a simple empirical model with a parameter for selection pressure, calculated from weed relative abundance and glyphosate efficacy, and a parameter for seedbank longevity, kochia, wild oat, and green foxtail were the top three weeds, respectively, predicted at risk of selection for glyphosate resistance in the semiarid Grassland region of the Canadian prairies; wild oat, green foxtail, and cleavers species were predicted at greatest risk in the subhumid Parkland region. This study confirms the first occurrence of a GR weed in western Canada. Future research on GR kochia will include monitoring, biology and ecology, fitness, mechanism of resistance, and best management practices.

Widespread Occurrence of Herbicide-Resistant Italian Ryegrass (Lolium multiflorum) in Northern Idaho and Eastern Washington

2010 ◽  
Vol 24 (3) ◽  
pp. 281-288 ◽  
Author(s):  
Traci A. Rauch ◽  
Donald C. Thill ◽  
Seth A. Gersdorf ◽  
William J. Price
Keyword(s):  
Pacific Northwest ◽  
Cropping Systems ◽  
Lolium Multiflorum ◽  
Acetolactate Synthase ◽  
Italian Ryegrass ◽  
Cross Resistance ◽  
Herbicide Resistant ◽  
Group 2 ◽  
Northern Idaho ◽  
Eastern Washington

Persistent use of herbicides has resulted in the selection of many herbicide-resistant weeds worldwide. A survey of 75 fields in the Palouse region of the inland Pacific Northwest was conducted to determine the extent of Italian ryegrass resistance to grass herbicides commonly used in winter wheat-cropping systems. Plants grown from collected seed samples were tested for resistance to diclofop, clodinafop, quizalofop, tralkoxydim, sethoxydim, clethodim, pinoxaden, triasulfuron, mesosulfuron, flucarbazone, imazamox, and flufenacet/metribuzin. Averaged across herbicide families within a herbicide group, some level of resistance was exhibited in 73, 31, and 31% of the populations to the aryloxyphenoxypropionates, cyclohexanediones, and phenylpyrazoline herbicides, respectively, and 39, 53, and 55% of the populations to the sulfonylureas, sulfonylaminocarbonyltriazolinone, and imidazolinone herbicides, respectively. Twelve percent of the populations showed some level of resistance to flufenacet/metribuzin. Cross-resistance to all acetyl coenzyme A carboxylase-inhibiting (group 1) herbicides was observed in 12% of the populations, whereas 25% of the populations were cross-resistant to all acetolactate synthase-inhibiting (group 2) herbicides tested. Of all the populations tested, 7% exhibited multiple resistance to at least one herbicide within all three groups tested. Only 5% of populations were completely susceptible to all 12 herbicides tested. These results indicate that herbicide-resistant Italian ryegrass populations are now common across much of the Palouse region in northern Idaho and eastern Washington.

scholarly journals Early Virological Failure in Naive Human Immunodeficiency Virus Patients Receiving Saquinavir (Soft Gel Capsule)-Stavudine-Zalcitabine (MIKADO Trial) Is Not Associated with Mutations Conferring Viral Resistance

2000 ◽  
Vol 38 (7) ◽  
pp. 2726-2730 ◽  
Author(s):  
M. Mouroux ◽  
A. Yvon-Groussin ◽  
G. Peytavin ◽  
C. Delaugerre ◽  
M. Legrand ◽  
...  
Keyword(s):  
Viral Load ◽  
Virological Failure ◽  
Viral Resistance ◽  
Resistance Testing ◽  
Genotypic Resistance ◽  
Phenotypic Resistance ◽  
Genotypic Resistance Testing ◽  
Immunodeficiency Virus ◽  
Group 2 ◽  
Group 1

The MIKADO trial was designed to evaluate the efficacy of stavudine-zalcitabine-saquinavir (soft gel capsule) [d4T-ddC-SQV(SGC)] in 36 naive patients (−3.3 log10units at week 24 [W24]). Among the 29 patients remaining on d4T-ddC-SQV(SGC) until W24, 10 harbored a virological failure (viral load of >200 copies/ml at W24) (group 1). To determine the reasons for therapeutic failure, genotypic and phenotypic resistance test results and SQV concentrations in plasma were analyzed and compared to those in successfully treated patients (viral load of <200 copies/ml at W24) (group 2). Reverse transcriptase and protease genotypic analyses in group 1 revealed the acquisition of only one SQV-associated mutation (L90M) in only two patients. There was no significant increase in the 50 or 90% inhibitory concentration of SQV in patients with or without the L90M mutation. However, the fact that two patients developed an L90M mutation only 4 weeks after relapse points to the need for genotypic resistance testing in the context of an initial failure of the antiretroviral regimen. At W24, the median SQV concentration in group 1 (71 ng/ml) was significantly lower than in group 2 (475 ng/ml), and the plasma SQV concentration was correlated with the viral load at W24 (r = −0.5; P < 0.05) and with the drop in viral load between day 0 and W24 (r = −0.5; P < 0.01). These results and the fact that the plasma SQV concentrations in the two groups prior to relapse (W12) were not significantly different strongly suggest that the early failure of this combination is not due to viral resistance but to a lack of compliance, pharmacological variability, and drug interactions or a combination of these factors.

Nature, Occurrence, and Cost of Herbicide-Resistant Green Foxtail (Setaria viridis) Across Saskatchewan Ecoregions

1999 ◽  
Vol 13 (3) ◽  
pp. 626-631 ◽  
Author(s):  
Hugh J. Beckie ◽  
A. Gordon Thomas ◽  
Anne Légère
Keyword(s):  
Field Survey ◽  
Cross Resistance ◽  
Control Group ◽  
Setaria Viridis ◽  
Grain Elevators ◽  
Herbicide Resistant ◽  
Green Foxtail ◽  
Group 3 ◽  
Low Incidence ◽  
Group 1

In Saskatchewan, a field survey was conducted in 1996 and a grain elevator survey in 1997 to determine the nature and occurrence of herbicide-resistant (HR) biotypes of green foxtail (Setaria viridis). Based on results of the field survey, one in every 20 fields (1 million ha) in Saskatchewan is estimated to have acetyl-CoA carboxylase (ACCase) inhibitor (Group 1)-HR green foxtail. Of the samples received from 30 grain elevators, 83% had Group 1 resistance. Similar to the field survey, incidence of aryloxyphenoxy propionate (AOPP) resistance was much higher than cyclohexanedione (CHD) resistance. Both surveys indicated relatively low incidence of dinitroaniline (Group 3) resistance or cross-resistance (Groups 1 and 3). Most alternative herbicides to control Group 1-HR green foxtail in broadleaf crops and cross-HR biotypes in cereal and broadleaf crops increase costs to the grower.

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