INTERNATIONAL HERBICIDE-RESISTANT WEED DATABASE

MULTIPLE RESISTANT POWELL AMARANTH
(Amaranthus powellii)


Multiple Resistance: 2 Sites of Action
Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
Auxin Mimics HRAC Group 4 (Legacy O)

Canada, Ontario
INTRODUCTION POWELL AMARANTH
Powell Amaranth (Amaranthus powellii) is a dicot weed in the Amaranthaceae family.  In Ontario this weed first evolved multiple resistance (to 2 herbicide sites of action) in 2019 and infests Soybean.  Multiple resistance has evolved to herbicides in the Groups 2 (Legacy B), and Auxin Mimics HRAC Group 4 (Legacy O).  These particular biotypes are known to have resistance to aminopyralid, dichlorprop, imazethapyr, MCPA, and mecoprop and they may be cross-resistant to other herbicides in the Groups 2 (Legacy B), and Auxin Mimics HRAC Group 4 (Legacy O).

The 'Group' letters/numbers that you see throughout this web site refer to the classification of herbicides by their site of action. To see a full list of herbicides and HRAC herbicide classifications click here.

If we do not have a picture for this weed, or you can provide a better picture (scan, digital camera etc) please please e-mail it to us.

QUIK STATS (last updated Oct 06, 2022 )

Common NamePowell Amaranth
SpeciesAmaranthus powellii
GroupInhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)

Auxin Mimics HRAC Group 4 (Legacy O)
Herbicidesaminopyralid, dichlorprop, imazethapyr, MCPA, and mecoprop
LocationCanada, Ontario
Year2019
Situation(s)Soybean
Contributors - (Alphabetically)Martin Laforest, Darren Robinson, Peter Sikkema, Nader Soltani, and Francois Tardif 
Edit this Case  |  Add New Case of Resistance  |  Add Note

ACADEMIC ASPECTS

Confirmation Tests

Field trials comparing a known susceptible Powell Amaranth biotype with this Powell Amaranth biotype have been used to confirm resistance. For further information on the tests conducted please contact the local weed scientists that provided this information.
 
Genetics

Genetic studies on HRAC Group 2, 4 resistant Powell Amaranth have not been reported to the site.  There may be a note below or an article discussing the genetics of this biotype in the Fact Sheets and Other Literature
 
Mechanism of Resistance

The mechanism of resistance for this biotype is either unknown or has not been entered in the database.  If you know anything about the mechanism of resistance for this biotype then please update the database.
 
Relative Fitness

There is no record of differences in fitness or competitiveness of these resistant biotypes when compared to that of normal susceptible biotypes.  If you have any information pertaining to the fitness of multiple resistant Powell Amaranth from Ontario please update the database.
 
Edit Case  |  Add Note  |  Add Article  |  Add New Case  |  

CONTRIBUTING WEED SCIENTISTS

MARTIN LAFOREST
Research Scientist
Agriculture and Agri-food Canada
430 boul. Gouin
St-Jean-sur-Richelieju, J3B 3E6, Quebec
Canada
Email Martin Laforest
DARREN ROBINSON
Associate Professor
University of Guelph, Ridgetown Campus
Plant Agriculture
120 Main Street East
Ridgetown, N0P 2C0, Ontario
Canada
Email Darren Robinson
PETER SIKKEMA
Professor
University of Guelph Ridgetown Campus
Weed Management - Field Crops
120 Main Street East
Ridgetown, N0P 2C0, Ontario
Canada
Email Peter Sikkema
Web   : Web Site Link
NADER SOLTANI
Ad. Professor
University of Guelph Ridgetown Campus
Plant Agriculture
N6G0E5
London, N6G 0E5, Ontario
Canada
Email Nader Soltani
Web   : Web Site Link
FRANCOIS TARDIF
Associate Professor
University Of Guelph
Department Of Plant Agriculture
2055 Radatz Ave
Guelph, N1G 2W1, Ontario
Canada
Email Francois Tardif
Web   : Web Site Link

ACKNOWLEDGEMENTS

The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Ontario have been instrumental in providing you this information. Particular thanks is given to Martin Laforest, Darren Robinson, Peter Sikkema, Nader Soltani, and Francois Tardif for providing detailed information.
Herbicide Resistant Powell Amaranth Globally
(Amaranthus powellii)
Herbicide Resistant Powell Amaranth Globally
(Amaranthus powellii)
Drag a column header and drop it here to group by that column
Herbicide Resistant Powell Amaranth Globally
(Amaranthus powellii)
#CountryFirstYearSituationActive IngredientsSite of Action
1 Canada (Ontario) CanadaOntario1977 Corn (maize) atrazine, and metribuzin 7 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
15Amaranthus powelliiPowell Amaranth1158
2 Canada (Ontario) CanadaOntario1998 Corn (maize), Cropland, and Soybean imazethapyr, and thifensulfuron-methyl 7 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
15Amaranthus powelliiPowell Amaranth1159
3 Canada (Ontario) CanadaOntario1998 Corn (maize), Soybean, and Wheat atrazine, imazethapyr, and metribuzin 7 Multiple Resistance: 2 Sites of Action
Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
15Amaranthus powelliiPowell Amaranth5049
4 Canada (Ontario) CanadaOntario1999 Carrots atrazine, linuron, monolinuron, and prometryne 7 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
15Amaranthus powelliiPowell Amaranth5048
5 Canada (Manitoba) CanadaManitoba2008 Beans, and Wheat thifensulfuron-methyl, and tribenuron-methyl 7 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
15Amaranthus powelliiPowell Amaranth5631
6 Canada (Quebec) CanadaQuebec2012 Carrots linuron 7 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
15Amaranthus powelliiPowell Amaranth17123
7 Canada (Quebec) CanadaQuebec2012 Soybean imazethapyr 7 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
15Amaranthus powelliiPowell Amaranth17124
8 Canada (Ontario) CanadaOntario2019 Soybean aminopyralid, dichlorprop, imazethapyr, MCPA, and mecoprop 7 Multiple Resistance: 2 Sites of Action
Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
Auxin Mimics ( HRAC Group 4 (Legacy O)
15Amaranthus powelliiPowell Amaranth24243
9 Czech RepublicCzech Republic 1989 Orchards atrazine, cyanazine, prometryne, simazine, and terbutryne 12 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
15Amaranthus powelliiPowell Amaranth78
10 FranceFrance 1982 Corn (maize) atrazine 17 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
15Amaranthus powelliiPowell Amaranth452
11 SwitzerlandSwitzerland 1986 Corn (maize) atrazine 41 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
15Amaranthus powelliiPowell Amaranth197
12 United States (Washington) United StatesWashington1992 Mint terbacil 45 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
15Amaranthus powelliiPowell Amaranth331
13 United States (Ohio) United StatesOhio1996 Soybean imazaquin 45 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
15Amaranthus powelliiPowell Amaranth1100
14 United States (Michigan) United StatesMichigan2001 Asparagus, and Nurseries atrazine, and diuron 45 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
15Amaranthus powelliiPowell Amaranth5176
Literature about Similar Cases

Page size:
select
Page: of 4
Items 1 to 5 of 18

Page size:
select
Page: of 4
Items 1 to 5 of 18

PERMISSION MUST BE OBTAINED FIRST if you intend to base a significant portion of a scientific paper on data derived from this site. Citation:
Heap, I.  The International Herbicide-Resistant Weed Database.  Online.  Monday, December 5, 2022 .  Available  www.weedscience.org Copyright © 1993- 2022 WeedScience.org All rights reserved. Fair use of this material is encouraged. Proper citation is requested.