Herbicide Resistant Weeds

GROUP G/9 RESISTANT PALMER AMARANTH (Amaranthus palmeri)
USA: Missouri

Tuesday, September 07, 2010

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Palmer Amaranth

1.	Introduction
2.	Level of Infestation
3.	Quick Statistics
4.	Notes about this biotype
5.	Academic Aspects
6.	R Palmer 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

Palmer Amaranth (Amaranthus palmeri) is a dicot weed in the Amaranthaceae family. In Missouri this weed first evolved resistance to Group G/9 herbicides in 2008 and infests cotton, and soybean. Group G/9 herbicides are known as Glycines (Inhibition of EPSP synthase). Research has shown that these particular biotypes are resistant to glyphosate and they may be cross-resistant to other Group G/9 herbicides.

Local weed scientists estimate that Group G/9 resistant Palmer Amaranth in Missouri infests 6-10 sites and the number of sites are increasing. They also estimate that there are 1001-10000 acres infested with Group G/9 resistant Palmer Amaranth 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	Palmer Amaranth
Species	Amaranthus palmeri
Group	Glycines (G/9)
Herbicides	glyphosate
Location	USA, Missouri
Year	2008
Situation(s)	cotton, and soybean
Sites	6-10
Acres Infested	1001-10000
Contributors	Kevin Bradley
Input Data	Edit this Case \| Add New Case of Resistance \| Add Note

ACADEMIC ASPECTS

Confirmation Tests

Greenhouse trials comparing a known susceptible Palmer Amaranth biotype with this Palmer 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

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 G/9 resistant Palmer Amaranth from Missouri please update the database.

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HERBICIDE RESISTANT PALMER AMARANTH GLOBALLY
#	Country	Year	Sites	Acres	Mode of Action
1.	USA (South Carolina)	1989	501-1000	10001-100000	Dinitroanilines and others (K1/3)
2.	USA (Kansas)	1991	501-1000	10001-100000	ALS inhibitors (B/2)
3.	USA (Texas)	1993	2-5	11-50	Photosystem II inhibitors (C1/5)
4.	USA (Arkansas)	1994	101-500	10001-100000	ALS inhibitors (B/2)
5.	USA (Kansas)	1995	unknown	unknown	Photosystem II inhibitors (C1/5)
6.	USA (North Carolina)	1995	11-50	1001-10000	ALS inhibitors (B/2)
7.	USA (Texas)	1995	2-5	501-1000	Photosystem II inhibitors (C1/5)
8.	USA (Texas)	1995	2-5	501-1000	Photosystem II inhibitors (C1/5)
9.	USA (South Carolina)	1997	2-5	101-500	ALS inhibitors (B/2)
10.	USA (Georgia)	2000	2-5	101-500	ALS inhibitors (B/2)
11.	USA (Georgia)	2005	101-500	100001-1000000	Glycines (G/9)
12.	USA (North Carolina)	2005	unknown	100001-1000000	Glycines (G/9)
13.	USA (Arkansas)	2006	1001-10000	100001-1000000	Glycines (G/9)
14.	USA (Tennessee)	2006	1001-10000	10001-100000	ALS inhibitors (B/2)
15.	USA (Tennessee)	2006	2-5	101-500	Glycines (G/9)
16.	USA (Tennessee)	2006	1001-10000	100001-1000000	Glycines (G/9)
17.	USA (New Mexico)	2007	2-5	51-100	Glycines (G/9)
18.	USA (Mississippi) Multiple Resistance	2008	unknown	unknown	ALS inhibitors (B/2) Glycines (G/9)
19.	USA (Florida)	2008	11-50	1001-10000	ALS inhibitors (B/2)
20.	USA (Alabama)	2008	1	51-100	Glycines (G/9)
21.	USA (Missouri)	2008	6-10	1001-10000	Glycines (G/9)

FACT SHEETS AND OTHER LITERATURE	Format
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Scientific Abstracts on Herbicide Resistant Amaranthus palmeri
Transferal of herbicide resistance traits from Amaranthus palmeri to Amaranthus rudis.
Wetzel, D. K., M. Horak J., D. Skinner Z., and P. Kulakow A. 1999. Transferal of herbicide resistance traits from Amaranthus palmeri to Amaranthus rudis. Weed Science. 47: 538-543.
Palmer amaranth (Amaranthus palmeri) and common waterhemp (Amaranthus rudis) resistance to selected ALS-inhibiting herbicides.
Sprague, C. L., E. W. Stoller, L. M. Wax, and M. J. Horak. 1997. Palmer amaranth (Amaranthus palmeri) and common waterhemp (Amaranthus rudis) resistance to selected ALS-inhibiting herbicides. Weed Science. 45: 192-197.
Control and cross-resistance of an acetolactate synthase inhibitor-resistant Palmer amaranth (Amaranthus palmeri) biotype.
Gaeddert, J. W., D. E. Peterson, and M. J. Horak. 1997. Control and cross-resistance of an acetolactate synthase inhibitor-resistant Palmer amaranth (Amaranthus palmeri) biotype. Weed Technology. 11: 132-137.
Biotypes of Palmer amaranth (Amaranthus palmeri) and common waterhemp (Amaranthus rudis) are resistant to imazethapyr and thifensulfuron.
Horak, M. J. and D. E. Peterson. 1995. Biotypes of Palmer amaranth (Amaranthus palmeri) and common waterhemp (Amaranthus rudis) are resistant to imazethapyr and thifensulfuron. Weed Technology. 9: 192-195.
The history and present status of herbicide-resistant weed biotypes [Eleusine indica, Amaranthus palmeri and Xanthium strumarium] in South Carolina cotton.
Murdock, E. C., A. C. York, and B. J. Gossett. 1993. The history and present status of herbicide-resistant weed biotypes [Eleusine indica, Amaranthus palmeri and Xanthium strumarium] in South Carolina cotton. Proceedings, Beltwide Cotton Conferences, 10-14 January 1993, New Orleans, Louisiana, USA. : 1507.
Resistance of Palmer amaranth (Amaranthus palmeri) to the dinitroaniline herbicides.
Gossett, B. J., E. C. Murdock, and J. E. Toler. 1992. Resistance of Palmer amaranth (Amaranthus palmeri) to the dinitroaniline herbicides. Weed Technology. 6: 587-591.

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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