(Galium spurium)

Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)

Greece, Domokos, central Greece
False Cleavers (Galium spurium) is a dicot weed in the Rubiaceae family.  In Greece this weed first evolved resistance to Group 2 (Legacy B) herbicides in 2022 and infests Wheat.   Group 2 (Legacy B) herbicides are known as Inhibition of Acetolactate Synthase (Inhibition of Acetolactate Synthase ).  Research has shown that these particular biotypes are resistant to bensulfuron-methyl, florasulam, metsulfuron-methyl, and pyroxsulam and they may be cross-resistant to other Group 2 (Legacy B) 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.

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QUIK STATS (last updated Jun 08, 2023 )

Common NameFalse Cleavers
SpeciesGalium spurium
GroupInhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
Herbicidesbensulfuron-methyl, florasulam, metsulfuron-methyl, and pyroxsulam
LocationGreece, Domokos, central Greece
Contributors - (Alphabetically)Ian Heap 
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Control of resistant false cleavers (Galium spurium L.) population to ALS-inhibiting herbicides and its impact on the growth and yield of durum wheat.

Author(s) : Sparangis, P. ;  Efthimiadou, A. ;  Katsenios, N. ;  Karkanis, A.

Author Affiliation : Department of Agriculture, Plant Production and Rural Environment, University of Thessaly, Fytokou St., 38446 Volos, Greece.

Author Email ,

Journal article : Agronomy 2023 Vol.13 No.4  

Abstract : False cleavers (Galium spurium L.) is an annual broadleaf weed, commonly found in cereal crops around the world. It reduces crop yields mainly by the competition for nutrients and plant lodging, which decreases the photosynthetic rate of cultivated plants. Two field experiments were carried out in different locations to examine the efficacy of post-emergence herbicides against false cleavers in durum wheat (Triticum durum Desf.). Herbicides that belong to sulfonylureas, triazolopyrimidines, and other groups (e.g., nitriles and synthetic auxins) were applied. The results revealed that the herbicide florasulam + aminopyralid provided low efficacy (57%) against this weed species, while the most effective herbicides were bromoxynil + 2,4-D and halauxifen-methyl + florasulam. Bromoxynil + 2,4-D efficacy against false cleavers was 73% and 97% at Domokos and Velestino, respectively, while halauxifen-methyl + florasulam efficacy ranged between 89% and 97%. Moreover, the herbicides metsulfuron-methyl + bensulfuron-methyl and pyroxsulam/florasulam + 2,4-D provided low efficacy (<11%) against false cleavers, revealing resistance to ALS-inhibiting herbicides. Regarding the impact of false cleavers and other weed species on the growth of durum wheat, the results showed that the greatest dry biomass (8508.3-8922.7 kg ha-1 and 13,041.4-13,523 kg ha-1 at Domokos and Velestino, respectively) was found in the bromoxynil + 2,4-D, halauxifen-methyl + florasulam, and weed-free treatments. Similar results were also recorded for 1000-seed weights and crop yields, while there were no statistically significant differences among the treatments for spike length. Finally, our results revealed that the herbicides bromoxynil + 2,4-D and halauxifen-methyl + florasulam effectively controlled the resistant false cleavers population. However, it is important to note that halauxifen-methyl + florasulam was recently registered in Greece and other countries and, thus, should be used sensibly by farmers in a rotation with other herbicides to prevent the development of resistant populations.

ISSN : 2073-4395

DOI : 10.3390/agronomy13041087

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Confirmation Tests

Field trials comparing a known susceptible False Cleavers biotype with this False Cleavers biotype have been used to confirm resistance. For further information on the tests conducted please contact the local weed scientists that provided this information.

Genetic studies on HRAC Group 2 resistant False Cleavers 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

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 2 (Legacy B) resistant False Cleavers from Greece please update the database.
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International Survey of Herbicide-Resistant Weeds
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The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Greece have been instrumental in providing you this information. Particular thanks is given to Ian Heap for providing detailed information.
Herbicide Resistant False Cleavers Globally
(Galium spurium)
Herbicide Resistant False Cleavers Globally
(Galium spurium)
Drag a column header and drop it here to group by that column
Herbicide Resistant False Cleavers Globally
(Galium spurium)
#CountryFirstYearSituationActive IngredientsSite of Action
1 Canada (Alberta) CanadaAlberta1996 Canola, Cereals, and Wheat imazethapyr, metsulfuron-methyl, quinclorac, sulfometuron-methyl, thifensulfuron-methyl, triasulfuron, and tribenuron-methyl 7 Multiple Resistance: 2 Sites of Action
Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
Auxin Mimics ( HRAC Group 4 (Legacy O)
93Galium spuriumFalse Cleavers508
2 Canada (Saskatchewan) CanadaSaskatchewan2006 Spring Barley, and Wheat thifensulfuron-methyl, and tribenuron-methyl 7 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
93Galium spuriumFalse Cleavers5321
3 Canada (Manitoba) CanadaManitoba2008 Canola thifensulfuron-methyl, and tribenuron-methyl 7 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
93Galium spuriumFalse Cleavers5629
4 GreeceGreece 2022 Wheat bensulfuron-methyl, florasulam, metsulfuron-methyl, and pyroxsulam 19 Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
93Galium spuriumFalse Cleavers27278
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Heap, I.  The International Herbicide-Resistant Weed Database.  Online.  Thursday, July 18, 2024 .  Available Copyright © 1993- 2024 All rights reserved. Fair use of this material is encouraged. Proper citation is requested.