International Survey of Herbicide Resistant Weeds

Funded and Supported by the
Herbicide Resistance Action Committee (HRAC), the
  North American Herbicide Resistance Action Committee (NAHRAC),
and the Weed Science Society of America (WSSA).

The purpose of this survey is to monitor the evolution of herbicide-resistant weeds and assess their impact throughout the world.   Global collaboration between  weed scientists make the survey and this web site possible.

372 Resistant Biotypes, 201 Species (116 dicots and 85 monocots) and over 570,000 fields

Click Here for a Summary of Resistant Weeds by Site of Action
Criteria for Confirmation of Herbicide-Resistant Weeds
January 11, 2012  

 Researchers | USA Survey | Herbicides | Weed Photos | Contacts 

Select Lists of Herbicide Resistant Weeds by one of the below.

Global Summary
USA State Map

The "Weed Management Handbook" contains a great chapter on herbicide-resistant weeds.  Read more>>.



By MOA 2010! By Year 2010! Distribution 2010 Triazine 2010
Worst Weeds ALS inhibitors 2010 ACCase inhibitors 2010 Glyphosate 2010
Click on graphs for full size image.

Australian Glyphosate Sustainability Working Group The Australian Glyphosate Sustainability Working Group is a collaborative initiative involving research, industry and extension representatives with the purpose of promoting the sustainable use of the herbicide glyphosate in Australian agriculture.


Resistance 2011 To be held in Rothamsted on September 5th to 7th 2011


International Herbicide Resistance Conference, Perth 2013:

The Australian Herbicide Resistance Initiative


New Book: Glyphosate Resistance in Crops and Weeds: History, Development, and Management. Vijay K. Nandula

Does the mid-west need to beware of dicamba resistant Lambsquarters?

Dicamba resistant Chenopodium album in NewZealand, Paper 1

Dicamba resistant i>Chenopodium album in NewZealand, Paper 2


Dr. Ozair Chaudhry 2008. Herbicide-Resistance and Weed Resistance Management.


Glyphosate Resistant Johnsongrass Review


Glyphosate Resistant Palmer Amaranth found in Roundup Ready Cotton


New Italian Resistance Research - Paper 1- ALS resistant pigweed, Paper 2 - Resistant Weeds of Rice in Italy -  Maurizio Sattin


Criteria for Confirmation of Herbicide-Resistant Weeds PDF- with specific emphasis on confirming low level resistance.

ACCase Mutation Table PDF By: Christophe Délye, Dijon cédex.

Herbicide Resistance Studies in Yugoslavia - Dr. Branko Konstantinovic


Online Book: Mechanism of Herbicide Resistance in Weeds PDF By: Nishanth Tharayil-Santhakumar,  Plant &Soil Sciences University of Massachusetts Amherst, MA.


GLYPHOSATE RESISTANCE IN HORSEWEED (CONYZA CANADENSIS) FROM A WESTERN KENTUCKY FARM. PDF By: C.B. Rogers. Department of Agricultural and Human Sciences, Morehead State University, Morehead, KY 40351.


The effect of low growth temperature on Hill reaction and Photosystem 1 activities in three biotypes of Kochia scoparia (L.) Schrad. with different sensitivity to atrazine and ALS-inhibiting herbicides.  D. Holá1, M. Koèová1, O. Rothová1, D. Chodová2, J. Mikulka2

Herbicide Resistant Weeds in Korea - PowerPoint (4 mb) - Tae Seon Park

Another Glyphosate Resistant Weed Identified - Plantago lanceolata -  Andrew Cairns View Photo Here

Also see the recently identified glyphosate resistant Conyza bonariensis -  Andrew Cairns

Glyphosate Resistant Horseweed Map by county - by Joseph Dauer

Paper on Glyphosate Resistant Lolium multiflorum

ALS Mutations from Herbicide-Resistant Weeds
This new section of the website focuses on the amino acid substitutions that confer resistance to ALS inhibitor herbicides.  We aim to expand this section to include data on mutations that confer resistance to other herbicide modes of action.  The current section is based on a recent paper: "Tranel, P. J., and Wright, T. R. (2002). Resistance of weeds to ALS-inhibiting herbicides: What have we learned? WeedScience, 50: 700-712."

The section is maintained by Patrick Tranel and Terry Wright.

Papers on ACCase Resistance Mechanisms from France
Recent books on herbicide resistance
US Herbicide Trade Name Database - herbicide modes of action

Herbicide Site of Action Poster
HRAC has produced a poster illustrating the grouping of herbicides and their chemical structures.  Click here to view the poster

Download this new book on herbicide resistance weeds of rice - Free - Click Here
English and Spanish versions.
Glyphosate Resistant Ryegrass in South Africa and NSW (Australia) - Pictures of NSW infestations here - Pic1, Pic2, Pic3 - Thanks to Andrew Storrie


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Fair use of this material is encouraged. Proper citation is requested.