Herbicide Resistant Weeds

GROUP B/2 RESISTANT HORSEWEED (Conyza canadensis)
USA: Ohio

Tuesday, September 07, 2010

What's on this page

Horseweed

1.	Introduction
2.	Level of Infestation
3.	Quick Statistics
4.	Notes about this biotype
5.	Academic Aspects
6.	R Horseweed Globally
7.	Fact Sheets and Literature
8.	Contributing Weed Scientists
9.	Acknowledgements
10.	Where to now?

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Introduction

Level of Infestation

Horseweed (Conyza canadensis) is a dicot weed in the Asteraceae family. In Ohio this weed first evolved resistance to Group B/2 herbicides in 2001 and infests soybean. Group B/2 herbicides are known as ALS inhibitors (Inhibition of acetolactate synthase ALS (acetohydroxyacid synthase AHAS)). Research has shown that these particular biotypes are resistant to chlorimuron-ethyl, and cloransulam-methyl and they may be cross-resistant to other Group B/2 herbicides.

Local weed scientists estimate that Group B/2 resistant Horseweed in Ohio infests 101-500 sites and the number of sites are increasing. They also estimate that there are 1001-10000 acres infested with Group B/2 resistant Horseweed and the area infested is increasing.

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

QUIK STATS ( last updated Jan 31, 2005 )
Common Name	Horseweed
Species	Conyza canadensis
Group	ALS inhibitors (B/2)
Herbicides	chlorimuron-ethyl, and cloransulam-methyl
Location	USA, Ohio
Year	2001
Situation(s)	soybean
Sites	101-500
Acres Infested	1001-10000
Contributors	Mark Loux, and Jeff Stachler
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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse, and Laboratory trials comparing a known susceptible Horseweed biotype with this Horseweed 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

The genetic basis of resistance for this biotype is either unknown or has not been entered in the database. If you know anything about the genetic inheritance of this biotype please update the database.

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 B/2 resistant Horseweed from Ohio please update the database.

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HERBICIDE RESISTANT HORSEWEED GLOBALLY
#	Country	Year	Sites	Acres	Mode of Action
1.	Belgium	1989	unknown	unknown	Photosystem II inhibitors (C1/5)
2.	Belgium	1998	1	1-5	Bipyridiliums (D/22)
3.	Brazil	2005	11-50	501-1000	Glycines (G/9)
4.	Canada (Ontario)	1993	2-5	1-5	Bipyridiliums (D/22)
5.	China	2006	2-5	101-500	Glycines (G/9)
6.	Czech Republic	1987	501-1000	1001-10000	Photosystem II inhibitors (C1/5)
7.	Czech Republic	2007	2-5	unknown	Glycines (G/9)
8.	France	1981	unknown	unknown	Photosystem II inhibitors (C1/5)
9.	France	1988	unknown	unknown	Ureas and amides (C2/7)
10.	Israel Multiple Resistance	1993	2-5	101-500	ALS inhibitors (B/2) Photosystem II inhibitors (C1/5)
11.	Japan	1980	501-1000	10001-100000	Bipyridiliums (D/22)
12.	Poland	1983	101-500	unknown	Photosystem II inhibitors (C1/5)
13.	Poland	2000	1	unknown	ALS inhibitors (B/2)
14.	Spain	1987	6-10	51-100	Photosystem II inhibitors (C1/5)
15.	Spain	2006	2-5	101-500	Glycines (G/9)
16.	Switzerland	1982	51-100	501-1000	Photosystem II inhibitors (C1/5)
17.	United Kingdom	1982	51-100	unknown	Photosystem II inhibitors (C1/5)
18.	USA (Mississippi)	1994	11-50	1001-10000	Bipyridiliums (D/22)
19.	USA (Delaware)	2000	101-500	10001-100000	Glycines (G/9)
20.	USA (Tennessee)	2001	501-1000	2-5 million	Glycines (G/9)
21.	USA (Ohio)	2001	101-500	1001-10000	ALS inhibitors (B/2)
22.	USA (Kentucky)	2001	2-5	51-100	Glycines (G/9)
23.	USA (Ohio)	2002	101-500	1001-10000	Glycines (G/9)
24.	USA (Indiana)	2002	2-5	101-500	Glycines (G/9)
25.	USA (Maryland)	2002	6-10	501-1000	Glycines (G/9)
26.	USA (New Jersey)	2002	6-10	101-500	Glycines (G/9)
27.	USA (Michigan)	2002	11-50	10001-100000	ALS inhibitors (B/2)
28.	USA (Michigan) Multiple Resistance	2002	2-5	101-500	Photosystem II inhibitors (C1/5) Ureas and amides (C2/7)
29.	USA (Michigan)	2002	2-5	101-500	Ureas and amides (C2/7)
30.	USA (Missouri)	2002	101-500	10001-100000	Glycines (G/9)
31.	USA (Ohio) Multiple Resistance	2003	2-5	101-500	ALS inhibitors (B/2) Glycines (G/9)
32.	USA (Arkansas)	2003	6-10	1001-10000	Glycines (G/9)
33.	USA (Mississippi)	2003	101-500	1001-10000	Glycines (G/9)
34.	USA (North Carolina)	2003	2-5	6-10	Glycines (G/9)
35.	USA (Delaware)	2003	1	6-10	Bipyridiliums (D/22)
36.	USA (Pennsylvania)	2003	2-5	101-500	Glycines (G/9)
37.	USA (California)	2005	1	unknown	Glycines (G/9)
38.	USA (Illinois)	2005	1001-10000	100001-1000000	Glycines (G/9)
39.	USA (Kansas)	2005	51-100	10001-100000	Glycines (G/9)
40.	USA (Michigan)	2007	1	51-100	Glycines (G/9)
41.	USA (Mississippi) Multiple Resistance	2007	1	11-50	Bipyridiliums (D/22) Glycines (G/9)

FACT SHEETS AND OTHER LITERATURE	Format
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Scientific Abstracts on Herbicide Resistant Conyza canadensis
Inheritance of evolved glyphosate resistance in Conyza canadensis (L.) Cronq.
I. A. Zelaya , M. D. K. Owen and M. J. VanGessel 2004. Inheritance of evolved glyphosate resistance in Conyza canadensis (L.) Cronq. Theoretical and Applied Genetics . 110: 58-70.
Glyphosate-resistant horseweed from Delaware.
VanGessel, M.J. 2001. Glyphosate-resistant horseweed from Delaware. Weed Science. 49: 703-705.
Negative cross-resistance in triazine-resistant biotypes of Echinochloa crus-galli and Conyza canadensis.
Gadamski, G., D. Ciarka, J. Gressel, and S. Gawronski W. 2000. Negative cross-resistance in triazine-resistant biotypes of Echinochloa crus-galli and Conyza canadensis. Weed Science. 48: 176-180.
Effects of growth temperatures of 5 and 25 deg C on long-term responses of photosystem II to heat stress in atrazine-resistant and susceptible biotypes of Erigeron canadensis.
Dulai, S., I. Molnar, and E. Lehoczki. 1998. Effects of growth temperatures of 5 and 25 deg C on long-term responses of photosystem II to heat stress in atrazine-resistant and susceptible biotypes of Erigeron canadensis. Australian Journal of Plant Physiology. 25: 145-153.
Effect of paraquat measured via in vivo P-700 oxidation at 820 nm on paraquat-susceptible and resistant Erigeron canadensis (Cronq.) biotypes.
Cseh, R., L. Almasi, and E. Lehoczki. 1998. Effect of paraquat measured via in vivo P-700 oxidation at 820 nm on paraquat-susceptible and resistant Erigeron canadensis (Cronq.) biotypes. Photosynthesis: mechanisms and effects. Volume V. Proceedings of the XIth International Congress on Photosynthesis, Budapest, Hungary, 17 22 August, 1998. : 3905-3908.
Altered light response of xanthophyll cycle in herbicide-resistant Erigeron canadensis biotypes in the presence of paraquat.
Varadi, G., E. Darko, and E. Lehoczki. 1998. Altered light response of xanthophyll cycle in herbicide-resistant Erigeron canadensis biotypes in the presence of paraquat. Photosynthesis: mechanisms and effects. Volume V. Proceedings of the XIth International Congress on Photosynthesis, Budapest, Hungary, 17 22 August, 1998. : 3901-3904.
Paraquat resistance in horseweed (Conyza canadensis) and Virginia pepperweed (Lepidium virginicum) from Essex County, Ontario.
Smisek, A., C. Doucet, M. Jones, and S. Weaver. 1998. Paraquat resistance in horseweed (Conyza canadensis) and Virginia pepperweed (Lepidium virginicum) from Essex County, Ontario. Weed Science. 46: 200-204.
Are either SOD and catalase or the polyamines involved in the paraquat resistance of Conyza canadensis?
Szigeti, Z., I. Racz, E. Darko, D. Lasztity, and E. Lehoczki. 1996. Are either SOD and catalase or the polyamines involved in the paraquat resistance of Conyza canadensis? Journal of Environmental Science and Health. Part B, Pesticides, Food Contaminants, and Agricultural Wastes. 31: 599-604.
Fluorescence emission spectra of paraquat resistant Conyza canadensis during the chlorophyll fluorescence induction as determined by the CCD-OMA system.
Szigeti, Z., P. Richter, and H. K. Lichtenthaler. 1996. Fluorescence emission spectra of paraquat resistant Conyza canadensis during the chlorophyll fluorescence induction as determined by the CCD-OMA system. Journal of Plant Physiology. 148: 574-578.
Atrazine-resistant biotypes of Conyza canadensis have altered fluorescence quenching and xanthophyll cycle pattern.
Darko, E., G. Varadi, S. Dulai, and E. Lehoczki. 1996. Atrazine-resistant biotypes of Conyza canadensis have altered fluorescence quenching and xanthophyll cycle pattern. Plant Physiology and Biochemistry Paris. 34: 843-852.
Molecular survey of Polish resistant biotypes of weeds.
Gadamski, G., D. Ciarka, S. W. Gawronski, H. Brown (ed.), G. W. Cussans (ed.), M. D. Devine (ed.), S. O. Duke (ed.), C. Fernandez Quintanilla (ed.), A. Helweg (ed.), R. E. Labrada (ed.), M. Landes (ed.), P. Kudsk (ed.), and J. C. Streibig. 1996. Molecular survey of Polish resistant biotypes of weeds. Proceedings of the second international weed control congress, Copenhagen, Denmark, 25-28 June 1996. 1-4: 547-550.
Heat-induced modulated chlorophyll a fluorescence changes in atrazine-resistant and susceptible biotypes of Conyza canadensis (L.) Cronq.
Dulai, S., I. Molnar, E. Lehoczki, and P. Mathis. 1995. Heat-induced modulated chlorophyll a fluorescence changes in atrazine-resistant and susceptible biotypes of Conyza canadensis (L.) Cronq. Photosynthesis: from light to biosphere. Volume IV. Proceedings of the Xth international photosynthesis congress, Montpellier, France, 20-25 August 1995. : 921-924.
Comparison of photosensitivity of the photosynthetic apparatus in different light adapted atrazine-resistant and susceptible biotypes from Conyza canadensis (L.) Cronq.
Darko, E., G. Varadi, A. Hargitai, E. Nagy, E. Lehoczki, and P. Mathis. 1995. Comparison of photosensitivity of the photosynthetic apparatus in different light adapted atrazine-resistant and susceptible biotypes from Conyza canadensis (L.) Cronq. Photosynthesis: from light to biosphere. Volume IV. Proceedings of the Xth international photosynthesis congress, Montpellier, France, 20-25 August 1995. : 191-194.
Herbicide resistance in Denmark.
Andreasen, C. and J. E. Jensen. 1994. Herbicide resistance in Denmark. SP Rapport. 1994, presented at the 11th Danish plant protection conference on the side effect of pesticides used on weeds. 6: 261-270.
Effect of solar irradiation on the features of photosynthetic apparatus and on the growth of triazine susceptible and resistant biotypes of Erigeron canadensis L.
Stanek, R. 1994. Effect of solar irradiation on the features of photosynthetic apparatus and on the growth of triazine susceptible and resistant biotypes of Erigeron canadensis L. Third symposium on 'Climate of the cultivated field', Pulawy, Poland, 15-16 Oct. 1992. Zeszyty-Problemowe-Postepow-Nauk-Rolniczych. 405: 163-167.
Superoxide dismutase activity in response to paraquat resistance in Conyza canadensis (L.) Cronq.
Turcsanyi, E., G. Suranyi, E. Lehoczki, and G. Borbely. 1994. Superoxide dismutase activity in response to paraquat resistance in Conyza canadensis (L.) Cronq. Journal of Plant Physiology. 144: 599-606.
Xanthophyll cycle patterns and in vivo photoinhibition in herbicide-resistant biotypes of Conyza canadensis.
Varadi, G., E. Darko, E. Polos, Z. Szigeti, and E. Lehoczki. 1994. Xanthophyll cycle patterns and in vivo photoinhibition in herbicide-resistant biotypes of Conyza canadensis. Journal of Plant Physiology. 144: 669-674.
Diquat resistance of different paraquat resistant Conyza canadensis (L.) Cronq. biotypes.
Szigeti, Z., E. Darko, E. Nagy, and E. Lehoczki. 1994. Diquat resistance of different paraquat resistant Conyza canadensis (L.) Cronq. biotypes. Journal of Plant Physiology. 144: 686-690.
Influence of rye (Secale cereale) plant residues on germination and growth of three triazine-resistant and susceptible weeds.
Przepiorkowski, T. and S. F. Gorski. 1994. Influence of rye (Secale cereale) plant residues on germination and growth of three triazine-resistant and susceptible weeds. Weed Technology. 8: 744-747.
Mode of action of paraquat in leaves of paraquat-resistant Conyza canadensis (L.) Cronq.
Lehoczki, E., G. Laskay, I. Gaal, and Z. Szigeti. 1992. Mode of action of paraquat in leaves of paraquat-resistant Conyza canadensis (L.) Cronq. Plant, Cell and Environment. 15: 531-539.
Mutation of psbA gene in herbicide resistant populations of Erigeron canadensis [Conyza canadensis].
Gawronski, S. W., M. Sugita, M. Sugiura, and N. Murata. 1992. Mutation of psbA gene in herbicide resistant populations of Erigeron canadensis [Conyza canadensis]. Research in photosynthesis. Volume III. Proceedings of the IXth International Congress on Photosynthesis, Nagoya, Japan, August 30 September 4, 1992. : 405-407.
Paraquat resistance and its inheritance in seed germination of the foliar-resistant biotypes of Erigeron canadensis L. and E. sumatrensis Retz.
Yamasue, Y., K. Kamiyama, Y. Hanioka, and T. Kusanagi. 1992. Paraquat resistance and its inheritance in seed germination of the foliar-resistant biotypes of Erigeron canadensis L. and E. sumatrensis Retz. Pesticide Biochemistry and Physiology. 44: 21-27.
Paraquat induced changes of thylakoid structure of chloroplasts in horseweed [Conza canadensis (L.) Cronq.].
Szigeti, Z., E. Sarvari, and E. Lehoczki. 1991. Paraquat induced changes of thylakoid structure of chloroplasts in horseweed [Conza canadensis (L.) Cronq.]. Noventermeles. 40: 405-413.
Effect of NO3 ions on the photosystem II photoinhibition of triazine resistant and susceptible plants of Erigeron canadensis L.
Stanek, R. 1991. Effect of NO3 ions on the photosystem II photoinhibition of triazine resistant and susceptible plants of Erigeron canadensis L. Acta Physiologiae Plantarum. 13: 211-214.
Studies on the distribution of Erigeron canadensis resistant to paraquat in mulberry fields in Saitama Prefecture.
Hanioka, Y. 1991. Studies on the distribution of Erigeron canadensis resistant to paraquat in mulberry fields in Saitama Prefecture. Weed Research Tokyo. 36: 298-300.
Short-term paraquat effects on paraquat-resistant horseweed, Conyza canadensis Cronq.
Varadi, G., E. Lehoczki, Z. Szigeti, and E. Polos. 1990. Short-term paraquat effects on paraquat-resistant horseweed, Conyza canadensis Cronq. Proceedings of the 9th Australian Weeds Conference. : 257-259.
Triazine-resistant weeds, Conyza canadensis and Epilobium ciliatum: Importance and control in young conifer plantations.
Rubow, T., R. Cavalloro (ed.), and G. Noye (ed.). 1989. Triazine-resistant weeds, Conyza canadensis and Epilobium ciliatum: Importance and control in young conifer plantations. Importance and perspectives on herbicide-resistant weeds. Proceedings of a meeting of the EC Experts' Group, Tollose, Denmark, 15-17 November 1988. 11561: 97-104.
Paraquat-resistant biotype of Youngia japonica (L.) DC. in mulberry fields in Saitama Prefecture.
Hanioka, Y. 1989. Paraquat-resistant biotype of Youngia japonica (L.) DC. in mulberry fields in Saitama Prefecture. Weed Research Tokyo. 34: 163-168.
Paraquat-resistant biotype of Erigeron sumatrensis RETZ. in mulberry fields in Saitama Prefecture.
Hanioka, Y. 1989. Paraquat-resistant biotype of Erigeron sumatrensis RETZ. in mulberry fields in Saitama Prefecture. Weed Research Tokyo. 34: 210-214.
Herbicide-resistant weeds and search for biocontrol agents in Yugoslavia.
Sovljanski, B., M. Arsenovic, Z. Klokocar Smit, V. Janjic, Z. Ostojic, R. Cavalloro (ed.), and G. Noye (ed.). 1989. Herbicide-resistant weeds and search for biocontrol agents in Yugoslavia. Importance and perspectives on herbicide-resistant weeds. Proceedings of a meeting of the EC Experts' Group, Tollose, Denmark, 15-17 November 1988. 11561: 153-160.
The identification of triazine- and paraquat-resistant weed biotypes and their response to other herbicides.
Clay, D. V., C. Underwood, R. Cavalloro (ed.), and G. Noye (ed.). 1989. The identification of triazine- and paraquat-resistant weed biotypes and their response to other herbicides. Importance and perspectives on herbicide-resistant weeds. Proceedings of a meeting of the EC Experts' Group, Tollose, Denmark, 15-17 November 1988. : 47-55.
Peculiar feature of resistance to atrazine and linuron in Amaranthus lividus L. and Erigeron canadensis L.
Beuret, E. 1988. Peculiar feature of resistance to atrazine and linuron in Amaranthus lividus L. and Erigeron canadensis L. VIIIe Colloque International sur la Biologie, l'Ecologie et la Systematique des Mauvaises Herbes. 1: 277-286.
Occurrence and conditions of development of Conyza canadensis Cronq. (L.) populations co-resistant to atrazine and paraquat along the Szentendre local railway line.
Solymosi, P. 1988. Occurrence and conditions of development of Conyza canadensis Cronq. (L.) populations co-resistant to atrazine and paraquat along the Szentendre local railway line. Novenyvedelem. 24: 120-122.
Searching for atrazine resistant weed populations in Czechoslovakia.
Chodova, D. 1988. Searching for atrazine resistant weed populations in Czechoslovakia. Fragmenta Herbologica Jugoslavica. 17: 37-43.
Using the Hill reaction to distinguish between atrazine-resistant and sensitive weed biotypes.
Kockova, M., D. Chodova, and J. Mikulka. 1988. Using the Hill reaction to distinguish between atrazine-resistant and sensitive weed biotypes. Agrochemia. 28: 87-90.
Occurrence of the triazine herbicide resistant populations of pale persicaria (Polygonum lapathifolium).
Mikulka, J., D. Chodova, and M. Kocova. 1988. Occurrence of the triazine herbicide resistant populations of pale persicaria (Polygonum lapathifolium). Sbornik Uvtiz, Ochrana Rostlin. 24: 297-302.
Paraquat and atrazine co-resistance in Conyza canadensis (L.) Cronq.
Polos, E., J. Mikulas, Z. Szigeti, B. Matkovics, D. Q. Hai, A. Parducz, and E. Lehoczki. 1988. Paraquat and atrazine co-resistance in Conyza canadensis (L.) Cronq. Pesticide Biochemistry and Physiology. 30: 142-154.
Photosynthetic properties and cross-resistance to some urea herbicides of triazine-resistant Conyza canadensis Cronq (L.).
Polos, E., G. Laskay, Z. Szigeti, S. Pataki, and E. Lehoczki. 1987. Photosynthetic properties and cross-resistance to some urea herbicides of triazine-resistant Conyza canadensis Cronq (L.). Zeitschrift fur Naturforschung. Section C, Biosciences. 42: 783-793.
Cross-resistance to paraquat and atrazine in Conyza canadensis.
Polos, E., J. Mikulas, Z. Szigeti, G. Laskay, and E. Lehoczki. 1987. Cross-resistance to paraquat and atrazine in Conyza canadensis. Proceedings 1987 British Crop Protection Conference, Weeds. 3: 909-916.
Resistance of the horse weed (Conyza canadensis) to herbicides.
Polos, A. 1986. Resistance of the horse weed (Conyza canadensis) to herbicides. Dissertation Abstracts International, C European Abstracts. 47: 340.
Triazine resistance in Erigeron canadensis L. IV. Investigated by thermoluminescence measurement.
Rashid, A. and S. Demeter. 1986. Triazine resistance in Erigeron canadensis L. IV. Investigated by thermoluminescence measurement. Indian Journal of Plant Physiology. 29: 335-344.
Movement of paraquat in resistant and susceptible biotypes of Erigeron philadelphicus and E. canadensis.
Tanaka, Y., H. Chisaka, and H. Saka. 1986. Movement of paraquat in resistant and susceptible biotypes of Erigeron philadelphicus and E. canadensis. Physiologia Plantarum. 66: 605-608.
Herbicide resistance of horseweed (Conyza canadensis) in Hungarian vineyards.
Polos, E., J. Mikulas, G. Laskay, and E. Lehoczki. 1985. Herbicide resistance of horseweed (Conyza canadensis) in Hungarian vineyards. Proceedings 1985 British Crop Protection Conference, Weeds. 1: 187-195.
The spread of Erigeron canadensis L. in grapevine plantations and means of control.
Mikulas, J. and E. Polos. 1983. The spread of Erigeron canadensis L. in grapevine plantations and means of control. Novenyvedelem. 19: 149-154.
The build-up of resistant lines of arable weeds after continued use of herbicides, especialy triazines. Present state of knowledge of causes and practical consequences.
Bachthaler, G., H. Kees, and B. Dinzenhofer. 1983. The build-up of resistant lines of arable weeds after continued use of herbicides, especialy triazines. Present state of knowledge of causes and practical consequences. Nachrichtenblatt des Deutschen Pflanzenschutzdienstes. 35: 161-168.

CONTRIBUTING WEED SCIENTISTS

MARK LOUX	Edit
The Ohio State University 2021 Coffey Road Columbus, 43210, Ohio USA Email Mark Loux

JEFF STACHLER	Edit
Ohio State University Horticulture and Crop Science 223 Kottman Hall 2021 Coffey Rd Columbus, 43210, Ohio USA Email Jeff Stachler

Acknowledgements

Where to now?

The Herbicide Resistance Action Committee, The North American Herbicide Resistance Action Committee, the Weed Science Society of America, and weed scientists in Ohio have been instrumental in providing you this information. Particular thanks is given to Mark Loux, and Jeff Stachler for providing detailed information.

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