INTERNATIONAL HERBICIDE-RESISTANT WEED DATABASE

HRAC GROUP 4 (LEGACY O) RESISTANT COMMON RAGWEED
(Ambrosia artemisiifolia)


Auxin Mimics HRAC Group 4 (Legacy O)

United States, Michigan
INTRODUCTION COMMON RAGWEED
Common Ragweed (Ambrosia artemisiifolia) is a dicot weed in the Asteraceae family.  In Michigan this weed first evolved resistance to Group 4 (Legacy O) herbicides in 2022 and infests Christmas Trees.   Group 4 (Legacy O) herbicides are known as Auxin Mimics (Auxin Mimics ).  Research has shown that these particular biotypes are resistant to clopyralid and they may be cross-resistant to other Group 4 (Legacy O) herbicides.

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.

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QUIK STATS (last updated Jun 03, 2023 )

Common NameCommon Ragweed
SpeciesAmbrosia artemisiifolia
GroupAuxin Mimics HRAC Group 4 (Legacy O)
Herbicidesclopyralid
LocationUnited States, Michigan
Year2022
Situation(s)Christmas Trees
Contributors - (Alphabetically)Erin Hill 
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NOTES ABOUT THIS BIOTYPE

GENERAL

Erin Hill

Alternative integrated weed management options for clopyralid-resistant common ragweed.

Author(s) : Gallina, G. ;  Cregg, B. ;  Patterson, E. ;  Hill, E. ;  Saha, D.

Author Affiliation : Department of Horticulture, Michigan State University, 1066 Bogue Street, East Lansing, MI 48824, USA.

Author Email : gallinag@msu.edu ,  cregg@msu.edu ,  patte543@msu.edu ,  hiller12@msu.edu ,  sahadeb2@msu.edu

Journal article : Horticulturae 2023 Vol.9 No.9 ref.17

Abstract : Common ragweed (Ambrosia artemisiifolia L.) is an extremely competitive broadleaved summer annual weed found in Christmas tree production systems within Michigan. Common ragweed has been reported to have resistance to glyphosate, PSII inhibitors, PPO inhibitors, and ALS herbicides. There have been reports from Michigan Christmas tree growers of common ragweed resistance to clopyralid, a synthetic auxin herbicide, in Montcalm County, Michigan. The objective of this study was to test alternative post-emergence herbicide combinations and organic mulch on clopyralid-resistant common ragweed for weed control efficacy. The following two stages of common ragweed were used: stage 1 (6-9 leaves) and stage 2 (12-14 leaves). For common ragweed in stage 1 in 2021 and 2022, as well as stage 2 in 2022, at all evaluation dates, mulch + clopyralid + oxyfluorfen provided the highest level of weed control. For stage 1 in 2022, this treatment combination provided 100% control from 2 weeks after treatment (WAT) and always showed better or equal weed control compared to all the other treatments. The combination of mulch + clopyralid + glyphosate provided 100% control by 2 WAT when plants were treated at stage 2 in 2022. For the plants treated at stage 1 in 2022, many of the treatments reached a fresh weight of 0 g, but in 2021, those same treatments resulted in a fresh weight of around 20 g. Based on fresh weight, the greatest plant growth occurred with glyphosate treatment in 2021 and clopyralid and mulch alone in 2022. This is likely due to common ragweed's resistance to these herbicides.

ISSN : 2311-7524

DOI : 10.3390/horticulturae9090985

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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse trials comparing a known susceptible Common Ragweed biotype with this Common Ragweed 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 4 resistant Common Ragweed 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 Group 4 (Legacy O) resistant Common Ragweed from Michigan please update the database.
 
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CONTRIBUTING WEED SCIENTISTS

ERIN HILL
Weed Science Diagnostician
Michigan State University
Plant, Soil and Microbial Sciences
578 Wilson Rd.
East Lansing, 48824, Michigan
United States
Email Erin Hill
Web   : Web Site Link

ACKNOWLEDGEMENTS

The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Michigan have been instrumental in providing you this information. Particular thanks is given to Erin Hill for providing detailed information.
Herbicide Resistant Common Ragweed Globally
(Ambrosia artemisiifolia)
Herbicide Resistant Common Ragweed Globally
(Ambrosia artemisiifolia)
Drag a column header and drop it here to group by that column
Herbicide Resistant Common Ragweed Globally
(Ambrosia artemisiifolia)
#CountryFirstYearSituationActive IngredientsSite of Action
1 Canada (Ontario) CanadaOntario1976 Corn (maize), and Cropland atrazine 7 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
18Ambrosia artemisiifoliaCommon Ragweed59
2 Canada (Quebec) CanadaQuebec1999 Carrots linuron 7 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
18Ambrosia artemisiifoliaCommon Ragweed5064
3 Canada (Quebec) CanadaQuebec1999 Carrots linuron, and metribuzin 7 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
18Ambrosia artemisiifoliaCommon Ragweed17128
4 Canada (Ontario) CanadaOntario2000 Soybean chlorimuron-ethyl, cloransulam-methyl, and imazethapyr 7 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
18Ambrosia artemisiifoliaCommon Ragweed5471
5 Canada (Quebec) CanadaQuebec2007 Soybean cloransulam-methyl, and imazethapyr 7 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
18Ambrosia artemisiifoliaCommon Ragweed17127
6 Canada (Ontario) CanadaOntario2012 Soybean chlorimuron-ethyl, cloransulam-methyl, glyphosate, and imazamethabenz-methyl 7 Multiple Resistance: 2 Sites of Action
Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
18Ambrosia artemisiifoliaCommon Ragweed5713
7 Canada (Prince Edward Island) CanadaPrince Edward Island2023 Carrots linuron 7 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
18Ambrosia artemisiifoliaCommon Ragweed28275
8 FranceFrance 2013 Chickpea, Soybean, and Sunflower imazamox, metsulfuron-methyl, and tribenuron-methyl 17 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
18Ambrosia artemisiifoliaCommon Ragweed21230
9 SerbiaSerbia 2019 Corn (maize), Soybean, Sugar beets, and Sunflower imazamox, thiencarbazone-methyl, and tribenuron-methyl 245 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
18Ambrosia artemisiifoliaCommon Ragweed20224
10 UkraineUkraine 2023 Sunflower amidosulfuron, carfentrazone-ethyl, flazasulfuron, flumetsulam, foramsulfuron, imazamox, imazapyr, iodosulfuron-methyl-Na, nicosulfuron, and thiencarbazone-methyl 230 Multiple Resistance: 2 Sites of Action
Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
Inhibition of Protoporphyrinogen Oxidase ( HRAC Group 14 (Legacy E)
18Ambrosia artemisiifoliaCommon Ragweed26266
11 United States (Michigan) United StatesMichigan1990 Corn (maize), and Nurseries atrazine 45 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
18Ambrosia artemisiifoliaCommon Ragweed5181
12 United States (New York) United StatesNew York1993 Corn (maize) atrazine, cyanazine, and simazine 45 PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)
18Ambrosia artemisiifoliaCommon Ragweed1057
13 United States (Indiana) United StatesIndiana1998 Soybean cloransulam-methyl, and imazethapyr 45 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
18Ambrosia artemisiifoliaCommon Ragweed1113
14 United States (Illinois) United StatesIllinois1998 Soybean cloransulam-methyl, and imazethapyr 45 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
18Ambrosia artemisiifoliaCommon Ragweed1114
15 United States (Michigan) United StatesMichigan1998 Corn (maize), Nurseries, and Soybean cloransulam-methyl, imazamox, and imazethapyr 45 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
18Ambrosia artemisiifoliaCommon Ragweed1115
16 United States (Minnesota) United StatesMinnesota1998 Soybean cloransulam-methyl, imazethapyr, and primisulfuron-methyl 45 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
18Ambrosia artemisiifoliaCommon Ragweed1116
17 United States (Ohio) United StatesOhio1998 Soybean chlorimuron-ethyl, cloransulam-methyl, halosulfuron-methyl, imazamox, imazaquin, primisulfuron-methyl, and prosulfuron 45 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
18Ambrosia artemisiifoliaCommon Ragweed1117
18 United States (Missouri) United StatesMissouri2004 Soybean glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
18Ambrosia artemisiifoliaCommon Ragweed5228
19 United States (Arkansas) United StatesArkansas2004 Soybean glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
18Ambrosia artemisiifoliaCommon Ragweed5261
20 United States (Delaware) United StatesDelaware2005 Soybean acifluorfen, carfentrazone-ethyl, chlorimuron-ethyl, cloransulam-methyl, flumiclorac-pentyl, flumioxazin, fomesafen, halosulfuron-methyl, imazamox, imazapyr, imazaquin, imazethapyr, iodosulfuron-methyl-Na, lactofen, metsulfuron-methyl, oxyfluorfen, primisulfuron-methyl, pyraflufen-ethyl, pyrithiobac-sodium, sulfentrazone, and trifloxysulfuron-Na 45 Multiple Resistance: 2 Sites of Action
Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
Inhibition of Protoporphyrinogen Oxidase ( HRAC Group 14 (Legacy E)
18Ambrosia artemisiifoliaCommon Ragweed5265
21 United States (Ohio) United StatesOhio2006 Soybean chlorimuron-ethyl, cloransulam-methyl, and glyphosate 45 Multiple Resistance: 2 Sites of Action
Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
18Ambrosia artemisiifoliaCommon Ragweed5406
22 United States (Ohio) United StatesOhio2006 Soybean chlorimuron-ethyl, cloransulam-methyl, fomesafen, and lactofen 45 Multiple Resistance: 2 Sites of Action
Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
Inhibition of Protoporphyrinogen Oxidase ( HRAC Group 14 (Legacy E)
18Ambrosia artemisiifoliaCommon Ragweed5407
23 United States (North Carolina) United StatesNorth Carolina2006 Cotton glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
18Ambrosia artemisiifoliaCommon Ragweed7819
24 United States (North Carolina) United StatesNorth Carolina2006 Peanut (groundnut) diclosulam 45 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
18Ambrosia artemisiifoliaCommon Ragweed7857
25 United States (Kentucky) United StatesKentucky2006 Soybean glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
18Ambrosia artemisiifoliaCommon Ragweed7879
26 United States (Kansas) United StatesKansas2007 Soybean glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
18Ambrosia artemisiifoliaCommon Ragweed5305
27 United States (North Dakota) United StatesNorth Dakota2007 Soybean glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
18Ambrosia artemisiifoliaCommon Ragweed5507
28 United States (Indiana) United StatesIndiana2007 Soybean glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
18Ambrosia artemisiifoliaCommon Ragweed5519
29 United States (South Dakota) United StatesSouth Dakota2007 Corn (maize), and Soybean glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
18Ambrosia artemisiifoliaCommon Ragweed5635
30 United States (Minnesota) United StatesMinnesota2008 Soybean glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
18Ambrosia artemisiifoliaCommon Ragweed5506
31 United States (Pennsylvania) United StatesPennsylvania2008 Soybean glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
18Ambrosia artemisiifoliaCommon Ragweed7778
32 United States (Minnesota) United StatesMinnesota2010 Soybean cloransulam-methyl, glyphosate, and imazapyr 45 Multiple Resistance: 2 Sites of Action
Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
18Ambrosia artemisiifoliaCommon Ragweed7801
33 United States (Alabama) United StatesAlabama2013 Cotton glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
18Ambrosia artemisiifoliaCommon Ragweed7784
34 United States (New Jersey) United StatesNew Jersey2013 Soybean glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
18Ambrosia artemisiifoliaCommon Ragweed8916
35 United States (Nebraska) United StatesNebraska2013 Soybean glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
18Ambrosia artemisiifoliaCommon Ragweed8917
36 United States (Wisconsin) United StatesWisconsin2013 Soybean cloransulam-methyl 45 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
18Ambrosia artemisiifoliaCommon Ragweed10981
37 United States (Mississippi) United StatesMississippi2014 Soybean glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
18Ambrosia artemisiifoliaCommon Ragweed8900
38 United States (North Carolina) United StatesNorth Carolina2015 Corn (maize), and Soybean acifluorfen, cloransulam-methyl, fomesafen, glyphosate, lactofen, and nicosulfuron 45 Multiple Resistance: 3 Sites of Action
Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
Inhibition of Protoporphyrinogen Oxidase ( HRAC Group 14 (Legacy E)
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
18Ambrosia artemisiifoliaCommon Ragweed13036
39 United States (Michigan) United StatesMichigan2016 Soybean cloransulam-methyl, and fomesafen 45 Multiple Resistance: 2 Sites of Action
Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
Inhibition of Protoporphyrinogen Oxidase ( HRAC Group 14 (Legacy E)
18Ambrosia artemisiifoliaCommon Ragweed17106
40 United States (Maryland) United StatesMaryland2016 Soybean cloransulam-methyl, fomesafen, and glyphosate 45 Multiple Resistance: 3 Sites of Action
Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
Inhibition of Protoporphyrinogen Oxidase ( HRAC Group 14 (Legacy E)
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
18Ambrosia artemisiifoliaCommon Ragweed17109
41 United States (New Jersey) United StatesNew Jersey2016 Soybean cloransulam-methyl, fomesafen, and glyphosate 45 Multiple Resistance: 3 Sites of Action
Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
Inhibition of Protoporphyrinogen Oxidase ( HRAC Group 14 (Legacy E)
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
18Ambrosia artemisiifoliaCommon Ragweed17110
42 United States (Wisconsin) United StatesWisconsin2017 Corn (maize), and Soybean glyphosate 45 Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)
18Ambrosia artemisiifoliaCommon Ragweed17155
43 United States (Michigan) United StatesMichigan2022 Christmas Trees clopyralid 45 Auxin Mimics ( HRAC Group 4 (Legacy O)
18Ambrosia artemisiifoliaCommon Ragweed27277
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