<b>HRAC Group 1</b> <font size='2'> (Legacy A) </font> resistant Sorghum halepense from Israel

International Survey of Herbicide-Resistant Weeds

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Wednesday, July 16, 2025

HRAC GROUP 1 (LEGACY A) RESISTANT JOHNSONGRASS
(Sorghum halepense)

Inhibition of Acetyl CoA Carboxylase HRAC Group 1 (Legacy A)

Israel

INTRODUCTION		JOHNSONGRASS
Johnsongrass (Sorghum halepense) is a monocot weed in the Poaceae family. In Israel this weed first evolved resistance to Group 1 (Legacy A) herbicides in 2006 and infests Carrots, Cotton, Onions, and Peanut (groundnut). Group 1 (Legacy A) herbicides are known as Inhibition of Acetyl CoA Carboxylase (Inhibition of Acetyl CoA Carboxylase ). Research has shown that these particular biotypes are resistant to clethodim, fluazifop-butyl, and haloxyfop-methyl and they may be cross-resistant to other Group 1 (Legacy A) herbicides. The 'Group' letters/numbers that you see throughout this web site refer to the classification of herbicides by their site of action. To see a full list of herbicides and HRAC herbicide classifications click here.

QUIK STATS (last updated Apr 02, 2019 )
Common Name	Johnsongrass
Species	Sorghum halepense
Group	Inhibition of Acetyl CoA Carboxylase HRAC Group 1 (Legacy A)
Herbicides	clethodim, fluazifop-butyl, and haloxyfop-methyl
Location	Israel
Year	2006
Situation(s)	Carrots, Cotton, Onions, and Peanut (groundnut)
Contributors - (Alphabetically)	Ofri Gerson, Ofer Hochberg, Zvi Peleg, and Baruch Rubin
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NOTES ABOUT THIS BIOTYPE

GENERAL

Baruch Rubin

The initial biotype found in 2006 remained susceptible to clethodim. However other biotypes have been found, in 2016 in two fields- Kfar-Blum (KB) (in peanuts & carrot), Yagur (YG) (in cotton & onion). Sensitive population collected from an organic field in Ayanot (AY). The resistant biotypes were resistant to fluazifop and clethodim.

Molecular analyses showed both ACCase-resistant populations possess an altered target site - Trp₂₀₂₇ to Cys.

Ofri gerson (M.sc. student)

Professor Baruch Rubin (PI)

Professor Zvi Peleg (PI)

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ACADEMIC ASPECTS

Confirmation Tests

Field, and Greenhouse trials comparing a known susceptible Johnsongrass biotype with this Johnsongrass 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 HRAC Group 1 resistant Johnsongrass have not been reported to the site. 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 1 (Legacy A) resistant Johnsongrass from Israel 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

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 1 (Legacy A) resistant Johnsongrass from Israel please update the database.

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CONTRIBUTING WEED SCIENTISTS

OFRI GERSON

Graduate Hebrew University of Jerusalem Robert H. Smith Faculty of Agriculture Food and Environment POB 12 Rehovot, 7610001, Central District Israel Email Ofri Gerson

OFER HOCHBERG

M.sc Student The Hebrew University Of Jerusalem Rh Smith Institute Of Plant Sciences And Genetics In Agricul 9335 Hazard Way Ste 201 Rehovot, 76100, Central District Israel Email Ofer Hochberg

ZVI PELEG

Dr. Hebrew University of Jerusalem Faculty of Agriculture Food and Environment P.O.Box 12 Rehovot, 76100, Central District Israel Email Zvi Peleg Web : Web Site Link

BARUCH RUBIN

Professor Hebrew University Of Jerusalem Inst. Plant Sci. & Genetics In Agriculture Faculty Of Agric. Food & Environm. Rehovot, 76100, Israel Israel Email Baruch Rubin Web : Web Site Link

ACKNOWLEDGEMENTS
The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Israel have been instrumental in providing you this information. Particular thanks is given to Ofri Gerson, Ofer Hochberg, Zvi Peleg, and Baruch Rubin for providing detailed information.

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Herbicide Resistant Johnsongrass Globally
(Sorghum halepense)

Country

FirstYear

Situation

Active Ingredients

Site of Action

Argentina

2005

Soybean

glyphosate

Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)

Argentina

2015

Soybean

haloxyfop-methyl

Inhibition of Acetyl CoA Carboxylase ( HRAC Group 1 (Legacy A)

Argentina

2015

Soybean

clethodim, glyphosate, and haloxyfop-methyl

Multiple Resistance: 2 Sites of Action
Inhibition of Acetyl CoA Carboxylase ( HRAC Group 1 (Legacy A)
Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)

Australia (Queensland)

2019

Fallow

glyphosate

Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)

Chile

2009

Corn (maize)

nicosulfuron

Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)

Greece

2005

Cotton

propaquizafop, and quizalofop-ethyl

Inhibition of Acetyl CoA Carboxylase ( HRAC Group 1 (Legacy A)

Hungary

2015

Corn (maize), and Fallow

foramsulfuron, and nicosulfuron

Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)

Israel

2006

Carrots, Cotton, Onions, and Peanut (groundnut)

clethodim, fluazifop-butyl, and haloxyfop-methyl

Inhibition of Acetyl CoA Carboxylase ( HRAC Group 1 (Legacy A)

Israel

2017

Cotton, and Watermelon

rimsulfuron

Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)

Italy

2005

Soybean, and Tomatoes

fluazifop-butyl, haloxyfop-methyl, propaquizafop, and quizalofop-ethyl

Inhibition of Acetyl CoA Carboxylase ( HRAC Group 1 (Legacy A)

Italy

2007

Corn (maize)

nicosulfuron

Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)

Mexico

2009

Corn (maize)

foramsulfuron, nicosulfuron, primisulfuron-methyl, and rimsulfuron

Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)

Serbia

2014

Corn (maize)

imazamox, nicosulfuron, propoxycarbazone-Na, pyroxsulam, and rimsulfuron

Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)

Serbia

2017

Soybean

fenoxaprop-ethyl, fluazifop-butyl, haloxyfop-methyl, propaquizafop, and quizalofop-ethyl

Inhibition of Acetyl CoA Carboxylase ( HRAC Group 1 (Legacy A)

Serbia

2018

Soybean

fluazifop-butyl, and nicosulfuron

Multiple Resistance: 2 Sites of Action
Inhibition of Acetyl CoA Carboxylase ( HRAC Group 1 (Legacy A)
Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)

Spain

2015

Corn (maize)

nicosulfuron

Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)

United States (Mississippi)

1991

Cotton, and Cropland

fenoxaprop-ethyl, fluazifop-butyl, and quizalofop-ethyl

Inhibition of Acetyl CoA Carboxylase ( HRAC Group 1 (Legacy A)

United States (Kentucky)

1991

Soybean

fluazifop-butyl

Inhibition of Acetyl CoA Carboxylase ( HRAC Group 1 (Legacy A)

United States (Mississippi)

1992

Cotton

pendimethalin

Inhibition of Microtubule Assembly ( HRAC Group 3 (Legacy K1)

United States (Tennessee)

1995

Cotton, and Soybean

fluazifop-butyl, and quizalofop-ethyl

Inhibition of Acetyl CoA Carboxylase ( HRAC Group 1 (Legacy A)

United States (Virginia)

1995

Soybean

sethoxydim

Inhibition of Acetyl CoA Carboxylase ( HRAC Group 1 (Legacy A)

United States (Louisiana)

1997

Cotton

clethodim, and fluazifop-butyl

Inhibition of Acetyl CoA Carboxylase ( HRAC Group 1 (Legacy A)

United States (Texas)

2000

Corn (maize)

imazethapyr, and nicosulfuron

Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)

United States (West Virginia)

2004

Corn (maize)

nicosulfuron

Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)

United States (Indiana)

2005

Corn (maize), and Soybean

nicosulfuron

Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)

United States (Kentucky)

2006

Corn (maize)

foramsulfuron, nicosulfuron, and primisulfuron-methyl

Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)

United States (Arkansas)

2007

Soybean

glyphosate

Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)

United States (Mississippi)

2008

Soybean

glyphosate

Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)

United States (Louisiana)

2010

Soybean

glyphosate

Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)

United States (Missouri)

2019

Soybean

glyphosate

Inhibition of Enolpyruvyl Shikimate Phosphate Synthase ( HRAC Group 9 (Legacy G)

Venezuela

2010

Corn (maize)

foramsulfuron, iodosulfuron-methyl-Na, and nicosulfuron

Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)

Specific Papers about this Case

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Ferraro, D. O. ; Ghersa, C. M.. 2013. Fuzzy assessment of herbicide resistance risk: glyphosate-resistant johnsongrass, Sorghum halepense (L.) Pers., in Argentina's croplands. Crop Protection 51 : 32 - 39.

A fuzzy-logic based model was built in order to assess the relative influence of different ecological and management drivers on glyphosate resistance risk (GRR) in Sorghum halepense (L.) Pers. The model was hierarchically structured in a bottom-up manner by combining 16 input variables throughout a logical network. Input data were related to (1) herbicide usage, (2) crop rotation, (3) landscape characterization, (4) weed dispersal, and (5) mean maximum and minimum seasonal temperature. Mean maximum and minimum seasonal temperatures and the dominance of glyphosate use were the variables that showed the highest sensitivity to input changes. Application of the model at a regional scale resulted in a wide range of GRR values. The lowest range values (lower than 0 and between 0 and 0.25) were represented in 5.5% and 21.5% of the cropping area, respectively. Intermediate GRR range (between 0.25 and 0.5) were assessed in 57.3% of the cropping area whilst the highest GRR range values (0.5-0.7) were represented in only 15.6% of the studied area. The assessment of trade-offs between different ecosystem functions through expert opinion can complement traditional analyses for predicting herbicide resistance risk based on solely the genetic aspect of the evolutionary process..

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Literature about Similar Cases

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Hernandez, M.J., R. Leon, A. J. Fischer, M. Gebauer, R. Galdames, and R. FIgueroa. 2015. Target-Site Resistance to Nicosulfuron in Johnsongrass (Sorghum halepense) from Chilean Corn Fields.. Weed Science 63 : 631 - 640.

Johnsongrass is a common weed of corn in Chile, which is most often controlled by nicosulfuron, an acetohydroxyacid synthase (AHAS)-inhibiting herbicide. Recurrent nicosulfuron use has resulted in selection for resistant johnsongrass biotypes. We conducted studies to determine nicosulfuron resistance levels in two johnsongrass biotypes from Chile and to investigate if this resistance was target-site mediated. Whole-plant resistance to nicosulfuron was 33 and 46 times higher in resistant (R) than in susceptible (S) plants grown from seed and rhizomes, respectively. The nicosulfuron concentrations for 50% inhibition of AHAS enzyme activity in vitro were more than 11 times higher in R than in S plants. Sequencing analysis of the AHAS coding sequence revealed a Trp-574-Leu substitution in both R biotypes. This study shows that resistance to nicosulfuron in the two R biotypes is conferred by an altered target site. We also report the first consensus sequence of the johnsongrass AHAS gene corresponding to the known mutation sites conferring resistance to AHAS-inhibiting herbicides..

Vila-Aiub, M. M. ; Gundel, P. E. ; Yu Qin ; Powles, S. B.. 2013. Glyphosate resistance in Sorghum halepense and Lolium rigidum is reduced at suboptimal growing temperatures. Pest Management Science 69 : 228 - 232.

Background: Glyphosate resistance in populations of the C₄ perennial Sorghum halepense (Johnsongrass) and C₃ annual Lolium rigidum (rigid ryegrass) has evolved and been documented in many cropping areas around the globe. In S. halepense and in the majority of reported cases in L. rigidum the glyphosate resistance trait has been associated with a mechanism that reduces glyphosate translocation within plants. Here, the significant decrease in the glyphosate resistance level when resistant plants of S. halepense and L. rigidum are grown at suboptimal cool temperature conditions is reported. Results: Lowering temperature from 30 to 19°C in S. halepense and from 19 to 8°C in L. rigidum significantly reduced both plant survival and above-ground biomass produced by glyphosate-resistant plants. Thus, glyphosate resistance parameters significantly decreased when glyphosate-treated resistant plants of both species were grown under non-optimal temperature conditions. The results suggest that the resistance mechanism against glyphosate damage is less efficient at optimal growing temperatures. Conclusion: It is possible to increase the control of glyphosate-resistant S. halepense and L. rigidum populations by treatment with glyphosate during growing conditions at suboptimal low temperatures. Conversely, glyphosate failure will continue to occur on glyphosate-resistant populations treated during periods of higher temperatures..

Fernández, L. ; Haro, L. A. de ; Distefano, A. J. ; Martínez, M. C. ; Lía, V. ; Papa, J. C. ; Olea, I. ; Tosto, D. ; Hopp, H. E.. 2013. Population genetics structure of glyphosate-resistant Johnsongrass (Sorghum halepense L. Pers) does not support a single origin of the resistance. Ecology and Evolution 3 : 3388 - 3400.

Single sequence repeats (SSR) developed for Sorghum bicolor were used to characterize the genetic distance of 46 different Sorghum halepense (Johnsongrass) accessions from Argentina some of which have evolved toward glyphosate resistance. Since Johnsongrass is an allotetraploid and only one subgenome is homologous to cultivated sorghum, some SSR loci amplified up to two alleles while others (presumably more conserved loci) amplified up to four alleles. Twelve SSR providing information of 24 loci representative of Johnsongrass genome were selected for genetic distance characterization. All of them were highly polymorphic, which was evidenced by the number of different alleles found in the samples studied, in some of them up to 20. UPGMA and Mantel analysis showed that Johnsongrass glyphosate-resistant accessions that belong to different geographic regions do not share similar genetic backgrounds. In contrast, they show closer similarity to their neighboring susceptible counterparts. Discriminant Analysis of Principal Components using the clusters identified by K-means support the lack of a clear pattern of association among samples and resistance status or province of origin. Consequently, these results do not support a single genetic origin of glyphosate resistance. Nucleotide sequencing of the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) encoding gene from glyphosate-resistant and susceptible accessions collected from different geographic origins showed that none presented expected mutations in aminoacid positions 101 and 106 which are diagnostic of target-site resistance mechanism..

Vila-Aiub, M. M. ; Balbi, M. C. ; Distéfano, A. J. ; Fernández, L. ; Hopp, E. ; Yu Qin ; Powles, S. B.. 2012. Glyphosate resistance in perennial Sorghum halepense (Johnsongrass), endowed by reduced glyphosate translocation and leaf uptake. Pest Management Science 68 : 430 - 436.

BACKGROUND: In a large cropping area of northern Argentina, Sorghum halepense (Johnsongrass) has evolved towards glyphosate resistance. This study aimed to determine the molecular and biochemical basis conferring glyphosate resistance in this species. Experiments were conducted to assess target EPSPS gene sequences and ¹⁴C-glyphosate leaf absorption and translocation to meristematic tissues. RESULTS: Individuals of all resistant (R) accessions exhibited significantly less glyphosate translocation to root (11% versus 29%) and stem (9% versus 26%) meristems when compared with susceptible (S) plants. A notably higher proportion of the applied glyphosate remained in the treated leaves of R plants (63%) than in the treated leaves of S plants (27%). In addition, individuals of S. halepense accession R₂ consistently showed lower glyphosate absorption rates in both adaxial (10-20%) and abaxial (20-25%) leaf surfaces compared with S plants. No glyphosate resistance endowing mutations in the EPSPS gene at Pro-101-106 residues were found in any of the evaluated R accessions. CONCLUSION: The results of the present investigation indicate that reduced glyphosate translocation to meristems is the primary mechanism endowing glyphosate resistance in S. halepense from cropping fields in Argentina. To a lesser extent, reduced glyphosate leaf uptake has also been shown to be involved in glyphosate-resistant S. halepense..

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