Herbicide Resistant Weeds

Wednesday, September 08, 2010

What's on this page

Horseweed

1.	Resistant Weeds of Tennessee
2.	Resistance in Neighboring States
3.	Fact Sheets & Literature
4.	Resistance Experts in Tennessee
5.	Contributing Weed Scientists
6.	Acknowledgements
7.	Where to now?

If we do not have a picture for this weed, or you can provide a better picture (scan, digital camera etc) please please e-mail it to us.

Horseweed (Conyza canadensis) is the most widespread resistant weed of Tennessee

Introduction

About this page

There are currently 12 different types (known as 'biotypes') of herbicide resistant weeds in Tennessee. The first herbicide resistant weed reported from Tennessee is Goosegrass (Eleusine indica) with resistance to pendimethalin, and trifluralin, reported in 1988. Local weed scientists estimate that there are 12,810 sites and more than 4,183,400 acres infested with herbicide resistant weeds in Tennessee and they infest corn, cotton, soybean, and winter wheat. The most widespread resistant weed of Tennessee is Horseweed (Conyza canadensis), which infests an estimated 2-5 million acres and is found primarily in cotton, and soybean. Giant Ragweed (Ambrosia trifida), with resistance to glyphosate is the most recently discovered (2007) new type of resistant weed in Tennessee.

This is a resource page to assist you in managing herbicide-resistant weeds in Tennessee . If you have any questions regarding herbicide-resistant weeds in Tennessee please contact an expert in your area. If you have encountered a computer related error on the site then contact support@weedscience.org. If you are a weed scientist wanting to add or correct information on this page then please contact research@weedscience.org or add the information directly.

Scroll down this page to view tables on herbicide resistant weeds in Tennessee and its adjacent states as well as a list of articles about herbicide resistant weeds in your region. Click on the links within the table to view a case of resistance in more detail.

HERBICIDE RESISTANT WEEDS IN TENNESSEE
Weed	Situation	Herbicide Mode of Action	Year
Goosegrass (Eleusine indica)	cotton	K1/3 - Dinitroanilines and others (pendimethalin, trifluralin)	1988
Common cocklebur (Xanthium strumarium)	cotton	Z/17 - Organoarsenicals (DSMA, MSMA)	1991
Common cocklebur (Xanthium strumarium)	soybean	B/2 - ALS inhibitors (imazaquin)	1992
Johnsongrass (Sorghum halepense)	cotton, soybean	A/1 - ACCase inhibitors (fluazifop-P-butyl, quizalofop-P-ethyl)	1995
Lambsquarters (Chenopodium album)	corn	C1/5 - Photosystem II inhibitors (atrazine)	1998
Horseweed (Conyza canadensis)	cotton, soybean	G/9 - Glycines (glyphosate)	2001
Palmer Amaranth (Amaranthus palmeri)	cotton	B/2 - ALS inhibitors (pyrithiobac-Na)	2006
Palmer Amaranth (Amaranthus palmeri)	cotton	G/9 - Glycines (glyphosate)	2006
Palmer Amaranth (Amaranthus palmeri)	corn, cotton, soybean	G/9 - Glycines (glyphosate)	2006
Italian Ryegrass (Lolium multiflorum)	winter wheat	A/1 - ACCase inhibitors (diclofop-methyl)	2006
Tall Waterhemp (Amaranthus tuberculatus (syn. rudis))	soybean	B/2 - ALS inhibitors (cloransulam-methyl)	2007
Giant Ragweed (Ambrosia trifida)	cotton, soybean	G/9 - Glycines (glyphosate)	2007

HERBICIDE RESISTANT WEEDS IN ADJACENT STATES

ALABAMA
Species	MOA	Year
Annual Bluegrass	C1/5	1980
Goosegrass	K1/3	1987
Common cocklebur	Z/17	1988
Palmer Amaranth	G/9	2008

ARKANSAS
Species	MOA	Year
Goosegrass	K1/3	1989
Common cocklebur	Z/17	1989
Barnyardgrass	C2/7	1990
Palmer Amaranth	B/2	1994
Redroot Pigweed	B/2	1995
Italian Ryegrass	A/1	1995
Italian Ryegrass	B/2	1995
Common cocklebur	B/2	1995
Barnyardgrass	C2/7	1999
Barnyardgrass	O/4	1999
Horseweed	G/9	2003
Italian Ryegrass	B/2	2003
Common Ragweed	G/9	2004
Giant Ragweed	G/9	2005
Italian Ryegrass	A/1	2005
Palmer Amaranth	G/9	2006
Johnsongrass	G/9	2007
Italian Ryegrass	A/1	2008
Italian Ryegrass	B/2	2008
Italian Ryegrass	G/9	2008

GEORGIA
Species	MOA	Year
Goosegrass	K1/3	1992
Prickly Sida	B/2	1993
Italian Ryegrass	A/1	1995
Palmer Amaranth	B/2	2000
Palmer Amaranth	G/9	2005

KENTUCKY
Species	MOA	Year
Smooth Pigweed	C1/5	1987
Johnsongrass	A/1	1991
Smooth Pigweed	B/2	1992
Horseweed	G/9	2001

MISSOURI
Species	MOA	Year
Common cocklebur	B/2	1992
Tall Waterhemp	B/2	1994
Tall Waterhemp	C1/5	1994
Barnyardgrass	C2/7	1994
Common Sunflower	B/2	1996
Horseweed	G/9	2002
Common Ragweed	G/9	2004
Tall Waterhemp	B/2	2005
Tall Waterhemp	E/14	2005
Tall Waterhemp	G/9	2005
Palmer Amaranth	G/9	2008
Giant Ragweed	G/9	2009

MISSISSIPPI
Species	MOA	Year
Common cocklebur	B/2	1989
Johnsongrass	A/1	1991
Johnsongrass	K1/3	1992
Horseweed	D/22	1994
Goosegrass	K1/3	1994
Common cocklebur	Z/17	1994
Italian Ryegrass	B/2	1995
Annual Bluegrass	C1/5	1996
Horseweed	G/9	2003
Italian Ryegrass	G/9	2005
Horseweed	D/22	2007
Horseweed	G/9	2007
Palmer Amaranth	B/2	2008
Palmer Amaranth	G/9	2008
Tall Waterhemp	G/9	2010

NORTH CAROLINA
Species	MOA	Year
Goosegrass	K1/3	1973
Smooth Pigweed	C1/5	1980
Lambsquarters	C1/5	1980
Italian Ryegrass	A/1	1990
Common cocklebur	Z/17	1994
Palmer Amaranth	B/2	1995
Annual Bluegrass	C1/5	1995
Annual Bluegrass	K1/3	1997
Horseweed	G/9	2003
Palmer Amaranth	G/9	2005

SOUTH CAROLINA
Species	MOA	Year
Goosegrass	K1/3	1974
Common cocklebur	Z/17	1985
Palmer Amaranth	K1/3	1989
Italian Ryegrass	A/1	1990
Palmer Amaranth	B/2	1997

VIRGINIA
Species	MOA	Year
Smooth Pigweed	C1/5	1976
Lambsquarters	C1/5	1979
Redroot Pigweed	C1/5	1993
Italian Ryegrass	A/1	1993
Smooth Pigweed	B/2	1994
Johnsongrass	A/1	1995
Annual Bluegrass	C1/5	2001
Shattercane	B/2	2003
Common Chickweed	B/2	2008

HERBICIDE RESISTANT WEED CONTACTS IN TENNESSEE

Your local state university extension agent or local department of agriculture representative may be able to provide you with more information on herbicide-resistant weeds in your region. Much of the information about herbicide-resistant weeds in Tennessee has been provided by the following experts.

STATE CONTACTS

NEIL RHODES

University of Tennessee
P.O. Box 1071
Knoxville, 37901, Tennessee
United States of America
Phone : (423) 974-7208
Fax : (423) 974-8850
Email Neil Rhodes

LARRY STECKEL

Research/Extension Weed Specialist
University of Tennessee
Plant Sciences
605 Airways Blvd
Jackson, 38301, Tennessee
United States of America
Phone : 731-425-4705
Fax : 731-425-4720
Email Larry Steckel

Acknowledgements

Where to now?

The North American Herbicide Resistance Action Committee and weed scientists in Tennessee have been instrumental in providing you this information. Particular thanks is given to Neil Rhodes, and Larry Steckel for providing detailed information.

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