Herbicide Resistant Weeds

GROUP C1/5 RESISTANT POWELL AMARANTH (Amaranthus powellii)
Canada: Ontario

Saturday, July 31, 2010

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Powell Amaranth

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

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Introduction

Level of Infestation

Powell Amaranth (Amaranthus powellii) is a dicot weed in the Amaranthaceae family. In Ontario this weed first evolved resistance to Group C1/5 herbicides in 1977 and infests corn. Group C1/5 herbicides are known as Photosystem II inhibitors (Inhibition of photosynthesis at photosystem II). Research has shown that these particular biotypes are resistant to atrazine, and metribuzin and they may be cross-resistant to other Group C1/5 herbicides.

Local weed scientists estimate that Group C1/5 resistant Powell Amaranth in Ontario infests 501-1000 sites and the number of sites have stabilized. They also estimate that there are 10001-100000 acres infested with Group C1/5 resistant Powell Amaranth and the area infested has stabilized.

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 Dec 28, 2000 )
Common Name	Powell Amaranth
Species	Amaranthus powellii
Group	Photosystem II inhibitors (C1/5)
Herbicides	atrazine, and metribuzin
Location	Canada, Ontario
Year	1977
Situation(s)	corn
Sites	501-1000
Acres Infested	10001-100000
Contributors	Clarence Swanton, and Francois Tardif
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NOTES ABOUT THIS BIOTYPE

GENERAL

Clarence Swanton

Amaranthus powellii S. wats. to atrazine in 1977 in Ontario (Stephenson et al. 1990 Weed Technol. 4:199-207).

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GENERAL

Hugh Beckie

S. I. Warwick and S. E. Weaver. 1980. Atrazine resistance in Amaranthus retroflexus (redroot pigweed) and A. Powellii (green pigweed) from southern Ontario. Can. J. Plant Sci. 60:1485-1488. Also: S. E. Weaver and S. I. Warwick. 1982. Competitive relationships between atrazine resistant and susceptible populations of Amaranthus retroflexus and A. powellii from southern Ontario. New Phytol. 92:131-139. Also: S. E. Weaver, S. I. Warwick, and B. K. Thomson. 1982. Comparative growth and atrazine response of resistant and susceptible populations of Amaranthus from southern Ontario. J. Appl. Ecol. 19:611-620.

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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse, and Laboratory 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 Group C1/5 resistant Powell Amaranth indicate that inheritance is determined by a one gene, dominant, cytoplasmic trait. 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

Studies on the mechanism of resistance of Group C1/5 resistant Powell Amaranth from Ontario indicate that resistance is due to an altered target site. There may be a note below or an article discussing the mechanism of resistance in the "Fact Sheets and Other Literature"

Relative Fitness

Researchers have indicated that Group C1/5 resistant Powell Amaranth is ecologically less fit than normal susceptible Powell Amaranth. Triazine resistant weeds often exhibit a lower relative fitness when compared to susceptible biotypes. The most common mutation conferring triazine resistance (Ser 264 to Gly mutation of the psbA gene) also causes a reduction in CO₂ fixation, quantum yield, and seed and biomass production.. There may be a note below or an article discussing the fitness of this biotype in the "Fact Sheets and Other Literature"

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HERBICIDE RESISTANT POWELL AMARANTH GLOBALLY
#	Country	Year	Sites	Acres	Mode of Action
1.	Canada (Ontario)	1977	501-1000	10001-100000	Photosystem II inhibitors (C1/5)
2.	Canada (Ontario)	1998	101-500	10001-100000	ALS inhibitors (B/2)
3.	Canada (Ontario) Multiple Resistance	1998	1	unknown	ALS inhibitors (B/2) Photosystem II inhibitors (C1/5)
4.	Canada (Ontario) Multiple Resistance	1999	1	11-50	Photosystem II inhibitors (C1/5) Ureas and amides (C2/7)
5.	Czech Republic	1989	51-100	501-1000	Photosystem II inhibitors (C1/5)
6.	France	1982	unknown	unknown	Photosystem II inhibitors (C1/5)
7.	Switzerland	1986	2-5	6-10	Photosystem II inhibitors (C1/5)
8.	USA (Washington)	1992	unknown	unknown	Photosystem II inhibitors (C1/5)
9.	USA (Ohio)	1996	2-5	101-500	ALS inhibitors (B/2)
10.	USA (Michigan) Multiple Resistance	2001	11-50	101-500	Photosystem II inhibitors (C1/5) Ureas and amides (C2/7)

FACT SHEETS AND OTHER LITERATURE	Format
At Present there are no articles on this case of resistance. Please help by adding an article.
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Scientific Abstracts on Herbicide Resistant Amaranthus powellii
Characterization and diagnostic tests of resistance to acetohydroxyacid synthase inhibitors due to an Asp376Glu substitution in Amaranthus powellii
Ashigh, J., C. L. Corbett, P. J. Smith, J. Laplante, and F. J. Tardif. 2009. Characterization and diagnostic tests of resistance to acetohydroxyacid synthase inhibitors due to an Asp376Glu substitution in Amaranthus powellii Pesticide Biochemistry and Physiology. 95: 38-46.
mutation in the herbicide target site acetohydroxyacid synthase produces morphological and structural alterations and reduces fitness in Amaranthus powellii
Tardif, F. J., I. Rajcan, and M. Costea. 2006. mutation in the herbicide target site acetohydroxyacid synthase produces morphological and structural alterations and reduces fitness in Amaranthus powellii New Phytologist. 169: 251-264.
Mutations in ALS confer herbicide resistance in redroot pigweed (Amaranthus retroflexus) and Powell amaranth (Amaranthus powellii).
McNaughton, K. E., J. Letarte, E. A. Lee, and F. J. Tardif. 2005. Mutations in ALS confer herbicide resistance in redroot pigweed (Amaranthus retroflexus) and Powell amaranth (Amaranthus powellii). Weed Science. 53: 17-22.
Multiple resistance to imazethapyr and atrazine in Powell amaranth (Amaranthus powellii)
R. S. Diebold, K. E. McNaughton, E. A. Lee, and F. J. Tardif. 2003. Multiple resistance to imazethapyr and atrazine in Powell amaranth (Amaranthus powellii) Weed Science. 51: 312-318.
Mutations in the ALS gene confering resistance to group II herbicides in redroot pigweed (Amaranthus retroflexus) and green pigweed (A. powellii).
McNaughton, K. E., E. Lee A., and F. Tardif J. 2001. Mutations in the ALS gene confering resistance to group II herbicides in redroot pigweed (Amaranthus retroflexus) and green pigweed (A. powellii). Weed Science Society of America Abstracts. 41: 97.
Distribution and characteristics of triazine-resistant Powell amaranth (Amaranthus powellii) in Idaho.
Eberlein, C. V., K. Al Khatib, M. J. Guttieri, and E. P. Fuerst. 1992. Distribution and characteristics of triazine-resistant Powell amaranth (Amaranthus powellii) in Idaho. Weed Science. 40: 507-512.
Terbacil-resistant Powell amaranth.
Boydston, R. A., K. Al Khatib, and R. G. Lym. 1991. Terbacil-resistant Powell amaranth. Proceedings of the Western Society of Weed Science, Seattle, Washington, USA, 12-14 March 1991. 44: 21-25.
Atrazine action on the donor side of photosystem II in triazine-resistant and -susceptible weed biotypes.
Purcell, M., G. D. Leroux, and R. Carpentier. 1990. Atrazine action on the donor side of photosystem II in triazine-resistant and -susceptible weed biotypes. Pesticide Biochemistry and Physiology. 37: 83-89.
Emergence and growth rate of Amaranthus retroflexus biotypes sensitive and resistant to atrazine.
Zemanek, J. 1987. Emergence and growth rate of Amaranthus retroflexus biotypes sensitive and resistant to atrazine. Sbornik UVTIZ, Ochrana Rostlin. 23: 305-314.
Detection of atrazine-resistant biotypes of pigweed and goosefoot by the fluorescence method.
Chodova, D., J. Kral, and J. Zemanek. 1986. Detection of atrazine-resistant biotypes of pigweed and goosefoot by the fluorescence method. Agrochemia. 26: 205-207.
The occurrence of populations of pigweeds (Amaranthus spp.) resistant to atrazine in Czechoslovakia.
Zemanek, J. and J. Mikulka. 1985. The occurrence of populations of pigweeds (Amaranthus spp.) resistant to atrazine in Czechoslovakia. Sbornik UVTIZ Ochrana Rostlin. 21: 39-46.
Aspects of the biology and control of pigweed (Amaranthus spp.) in New York.
Senesac, A. F. 1985. Aspects of the biology and control of pigweed (Amaranthus spp.) in New York. Dissertation Abstracts International, B Sciences and Engineering. 46: 1007.
Atrazine metabolism in resistant and susceptible biotypes of Chenopodium album L., Chenopodium strictum Roth., and Amaranthus powellii S. Wats.
Khan, S. U., S. I. Warwick, and P. B. Marriage. 1985. Atrazine metabolism in resistant and susceptible biotypes of Chenopodium album L., Chenopodium strictum Roth., and Amaranthus powellii S. Wats. Weed Research. 25: 33-37.

CONTRIBUTING WEED SCIENTISTS

CLARENCE SWANTON	Edit
University of Guelph Dept. of Crop Science Ontario Agricultural College Guelph, N1G 2W1, ON Canada Email Clarence Swanton

FRANCOIS TARDIF	Edit
Associate Professor University of Guelph Department of Plant Agriculture Guelph, N1G 2W1, Ontario Canada Email Francois Tardif Web : Web Site Link

Acknowledgements

Where to now?

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 Clarence Swanton, and Francois Tardif for providing detailed information.

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