Herbicide Resistant Weeds

MULTIPLE RESISTANT TALL WATERHEMP (Amaranthus tuberculatus (syn. rudis))
Resistance to herbicides in groups B/2, E/14, and G/9
USA: Missouri

Saturday, July 31, 2010

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Tall Waterhemp

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

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Introduction

Level of Infestation

Tall Waterhemp (Amaranthus tuberculatus (syn. rudis)) is a dicot weed in the Amaranthaceae family. In Missouri this weed first evolved multiple resistance ( to 3 herbicide modes of action) in 2005 and infests corn, and soybean. Multiple resistance has evolved to herbicides in the Groups B/2, E/14, and G/9. These particular biotypes are known to have resistance to acifluorfen-Na, cloransulam-methyl, fomesafen, glyphosate, imazamox, imazethapyr, and lactofen and they may be cross-resistant to other herbicides in the Groups B/2, E/14, and G/9.

Local weed scientists estimate that multiple resistant Tall Waterhemp in Missouri infests 101-500 sites. They also estimate that there are 100001-1000000 acres infested with multiple resistant Tall Waterhemp 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 Feb 03, 2010 )
Common Name	Tall Waterhemp
Species	Amaranthus tuberculatus (syn. rudis)
Group	ALS inhibitors (B/2) PPO inhibitors (E/14) Glycines (G/9)
Herbicides	acifluorfen-Na, cloransulam-methyl, fomesafen, glyphosate, imazamox, imazethapyr, and lactofen
Location	USA, Missouri
Year	2005
Situation(s)	corn, and soybean
Sites	101-500
Acres Infested	100001-1000000
Contributors	Kevin Bradley
Input Data	Edit this Case \| Add New Case of Resistance \| Add Note

ACADEMIC ASPECTS

Confirmation Tests

Field, and Greenhouse trials comparing a known susceptible Tall Waterhemp biotype with this Tall Waterhemp 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 multiple resistant Tall Waterhemp from Missouri please update the database.

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HERBICIDE RESISTANT TALL WATERHEMP GLOBALLY
#	Country	Year	Sites	Acres	Mode of Action
1.	Canada (Ontario) Multiple Resistance	2002	1	11-50	ALS inhibitors (B/2) Photosystem II inhibitors (C1/5)
2.	Canada (Ontario)	2002	11-50	51-100	ALS inhibitors (B/2)
3.	USA (Iowa)	1993	501-1000	1001-10000	ALS inhibitors (B/2)
4.	USA (Illinois)	1993	10001-100000	2-5 million	ALS inhibitors (B/2)
5.	USA (Missouri)	1994	11-50	101-500	Photosystem II inhibitors (C1/5)
6.	USA (Missouri)	1994	1001-10000	2-5 million	ALS inhibitors (B/2)
7.	USA (Kansas)	1995	501-1000	100001-1000000	ALS inhibitors (B/2)
8.	USA (Kansas)	1995	6-10	501-1000	Photosystem II inhibitors (C1/5)
9.	USA (Nebraska)	1996	unknown	unknown	Photosystem II inhibitors (C1/5)
10.	USA (Iowa)	1996	unknown	unknown	Photosystem II inhibitors (C1/5)
11.	USA (Ohio)	1996	101-500	1001-10000	ALS inhibitors (B/2)
12.	USA (Illinois) Multiple Resistance	1996	11-50	1001-10000	ALS inhibitors (B/2) Photosystem II inhibitors (C1/5)
13.	USA (Wisconsin)	1999	11-50	1001-10000	ALS inhibitors (B/2)
14.	USA (Michigan)	2000	6-10	101-500	ALS inhibitors (B/2)
15.	USA (Kansas) Multiple Resistance	2001	11-50	501-1000	ALS inhibitors (B/2) PPO inhibitors (E/14)
16.	USA (Illinois)	2001	unknown	unknown	Photosystem II inhibitors (C1/5)
17.	USA (Oklahoma)	2002	101-500	1001-10000	ALS inhibitors (B/2)
18.	USA (Illinois) Multiple Resistance	2002	6-10	1001-10000	ALS inhibitors (B/2) Photosystem II inhibitors (C1/5) PPO inhibitors (E/14)
19.	USA (Missouri) Multiple Resistance	2005	101-500	100001-1000000	ALS inhibitors (B/2) PPO inhibitors (E/14) Glycines (G/9)
20.	USA (Kansas)	2006	2-5	101-500	Glycines (G/9)
21.	USA (Illinois) Multiple Resistance	2006	1	51-100	ALS inhibitors (B/2) Glycines (G/9)
22.	USA (Tennessee)	2007	6-10	501-1000	ALS inhibitors (B/2)
23.	USA (Minnesota)	2007	2-5	51-100	Glycines (G/9)
24.	USA (Iowa)	2009	11-50	unknown	PPO inhibitors (E/14)
25.	USA (Iowa)	2009	11-50	unknown	PPO inhibitors (E/14)
26.	USA (Iowa)	2009	2-5	unknown	Glycines (G/9)
27.	USA (Mississippi)	2010	2-5	101-500	Glycines (G/9)

FACT SHEETS AND OTHER LITERATURE	Format
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Scientific Abstracts on Herbicide Resistant Amaranthus tuberculatus
Multiple ALS mutations confer herbicide resistance in waterhemp (Amaranthus tuberculatus).
Patzoldt, W. L., and Tranel, P. J. 2007. Multiple ALS mutations confer herbicide resistance in waterhemp (Amaranthus tuberculatus). Weed Science. 55: 421-428.
A second triazine resistance mechanism in waterhemp
Tranel, P. J., Patzoldt, W. L., Dixon, B. S. and Riechers, D. E. 2003. A second triazine resistance mechanism in waterhemp . : .

CONTRIBUTING WEED SCIENTISTS

KEVIN BRADLEY	Edit
Asst. Professor & Extension Weed Scientist University of Missouri Division of Plant Sciences 206A Waters Hall Columbia, 65211, Missouri USA Email Kevin Bradley Web : Web Site Link

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 Missouri have been instrumental in providing you this information. Particular thanks is given to Kevin Bradley for providing detailed information.

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