Multiple resistant Digitaria sanguinalis from France

INTERNATIONAL HERBICIDE-RESISTANT WEED DATABASE

MULTIPLE RESISTANT LARGE CRABGRASS
(Digitaria sanguinalis)

Multiple Resistance: 2 Sites of Action
Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
Inhibition of Hydroxyphenyl Pyruvate Dioxygenase HRAC Group 27 (Legacy F2)

France

INTRODUCTION		LARGE CRABGRASS
Large Crabgrass (Digitaria sanguinalis) is a monocot weed in the Poaceae family. In France this weed first evolved multiple resistance (to 2 herbicide sites of action) in 2023 and infests Corn (maize). Multiple resistance has evolved to herbicides in the Groups 2 (Legacy B), and Inhibition of Hydroxyphenyl Pyruvate Dioxygenase HRAC Group 27 (Legacy F2). These particular biotypes are known to have resistance to mesotrione, and nicosulfuron and they may be cross-resistant to other herbicides in the Groups 2 (Legacy B), and Inhibition of Hydroxyphenyl Pyruvate Dioxygenase HRAC Group 27 (Legacy F2). 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 Oct 09, 2025 )
Common Name	Large Crabgrass
Species	Digitaria sanguinalis
Group	Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B) Inhibition of Hydroxyphenyl Pyruvate Dioxygenase HRAC Group 27 (Legacy F2)
Herbicides	mesotrione, and nicosulfuron
Location	France
Year	2023
Situation(s)	Corn (maize)
Contributors - (Alphabetically)	Christophe Délye
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NOTES ABOUT THIS BIOTYPE

GENERAL

Christophe Délye

Resistance to HPPD Inhibitors – A Rural Legend?

Authors: Christophe Délye & Séverine Michel

Institution: INRAE, UMR Agroécologie, Dijon
Published in: Phytoma, No. 785, Sept–Oct 2025

Abstract
Until now, resistance to HPPD-inhibiting herbicides had only been reported in a few isolated cases outside Europe. In France, however, poor control of weeds in maize fields has been observed for several years, suggesting possible resistance.

Study
Greenhouse bioassays were conducted on Echinochloa crus-galli (barnyardgrass) and Digitaria sanguinalis (large crabgrass). Three seed lots of each species, collected between 2017 and 2023 from monitoring networks, were tested for survival after application of mesotrione (HPPD inhibitor). Results were compared to reference populations with no known resistance.

Results
Resistance to mesotrione at the maximum authorized dose (150 g/ha) was confirmed in all six seed lots, and some even survived twice that dose (300 g/ha). Additionally, ALS inhibitor (nicosulfuron) resistance was identified in all Digitaria sanguinalis samples.
These findings represent the first confirmed global cases of resistance to an HPPD inhibitor in both species, and the first HPPD resistance cases reported in Europe.
The study highlights the urgent need to assess the prevalence of this resistance in France.

Keywords: Maize, HPPD inhibitor, Echinochloa crus-galli, Digitaria sanguinalis, mesotrione, ALS inhibitor, nicosulfuron.

Experimental Details

Sample origin: Seeds collected between 2017–2023 under the French national monitoring network (Ecophyto II plan).
Test conditions: Plants grown in greenhouse to 2–3 leaf stage; treated with:
- Mesotrione (Callisto, 100 g/L): 75, 150, and 300 g/ha
- Nicosulfuron (Pampa, 40 g/L): 60 g/ha
Reference: Non-resistant control population of Digitaria sanguinalis.
Assessment: 4 weeks post-application; plants with green leaves classified as resistant.

Key Findings

Resistance observed in all six populations tested — both Echinochloa crus-galli and Digitaria sanguinalis.
Survival at 2× mesotrione dose (300 g/ha) recorded in several samples:
- Digitaria sanguinalis: 4–43% resistant
- Echinochloa crus-galli: 2–10% resistant
Cross-resistance to both ALS (nicosulfuron) and HPPD inhibitors was found in Digitaria sanguinalis, with some plants double-resistant.
The earliest resistant samples were from 2017 (E. crus-galli) and 2020 (D. sanguinalis), suggesting these resistances have been present in France for several years.

Implications

This discovery confirms HPPD resistance in Europe for the first time.
The combination of HPPD and ALS resistance severely limits chemical control options for these grasses in maize.
The authors warn against herbicide underdosing, which can accelerate resistance selection.
Recommends integrated weed management combining:
- Non-chemical control (mechanical weeding, cover crops, rotation)
- Reduced herbicide frequency (full-dose treatments only where necessary)
- Diversified cropping systems.

Acknowledgments: Thanks to field collectors and contributors to the Ecophyto II and R4P surveillance networks.

References

Délye C. (2013). Phytoma No. 669, 24–29.
Délye C. et al. (2015). Phytoma No. 689, 39–42.
Heap I. (2025). International Herbicide-Resistant Weed Database (www.weedscience.org).
R4P Network (2025). Herbicide Resistance Map Update 2024.

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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse trials comparing a known susceptible Large Crabgrass biotype with this Large Crabgrass 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 2, 27 resistant Large Crabgrass 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 multiple resistant Large Crabgrass from France please update the database.

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CONTRIBUTING WEED SCIENTISTS

CHRISTOPHE DÉLYE

Chargé de Recherches INRA Agroécologie 17 rue de Sully Dijon, F-21000, Burgundy France Email Christophe Délye Web : Web Site Link

ACKNOWLEDGEMENTS
The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in France have been instrumental in providing you this information. Particular thanks is given to Christophe Délye for providing detailed information.

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Herbicide Resistant Large Crabgrass Globally
(Digitaria sanguinalis)

Country

FirstYear

Situation

Active Ingredients

Site of Action

Argentina

2019

Soybean

glyphosate

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

Australia (South Australia)

1993

Onions, and Vegetables

fluazifop-butyl, haloxyfop-methyl, and imazethapyr

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)

Canada (Ontario)

2011

Carrots, and Onions

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

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

China

2010

Corn (maize)

nicosulfuron

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

China

2011

Cotton

quizalofop-ethyl

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

Czech Republic

2005

Railways

atrazine

PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)

France

1983

Corn (maize)

atrazine

PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)

France

2005

Carrots

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

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

France

2015

Corn (maize)

foramsulfuron, and nicosulfuron

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

France

2023

Corn (maize)

mesotrione, and nicosulfuron

Multiple Resistance: 2 Sites of Action
Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)
Inhibition of Hydroxyphenyl Pyruvate Dioxygenase ( HRAC Group 27 (Legacy F2)

Italy

2006

Soybean

cycloxydim, and fluazifop-butyl

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

New Zealand

2022

Corn (maize)

nicosulfuron

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

Poland

1995

Orchards

atrazine

PSII inhibitors - Serine 264 Binders ( HRAC Group 5 (Legacy C1 C2)

Switzerland

2021

Corn (maize)

nicosulfuron

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

United States (Wisconsin)

1992

Carrots, and Onions

fluazifop-butyl, and sethoxydim

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

United States (Georgia)

2008

Turf

sethoxydim

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

Literature about Similar Cases

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Li, J., M. Li, X. Gao, and F. Fang. 2017. A novel amino acid substitution Trp574Arg in acetolactate synthase (ALS) confers broad resistance to ALS-inhibiting herbicides in crabgrass (Digitaria sanguinalis).. Pest Management Science doi:10.1002/ps.4651 : .

BACKGROUND Crabgrass (Digitaria sanguinalis) is an annual monocotyledonous weed. In recent years, field applications of nicosulfuron have been ineffective in controlling crabgrass populations in Shandong Province, China. To investigate the mechanisms of resistance to nicosulfuron in crabgrass populations, the acetolactate synthase (ALS) gene fragment covering known resistance-confering mutation sites was amplified and sequenced.

RESULTS Dose–response experiments suggested that the resistant population SD13 (R) was highly resistant to nicosulfuron (resistance index R/S = 43.7) compared with the sensitive population SD22 (S). ALS gene sequencing revealed a Trp574Arg substitution in the SD13 population, and no other known resistance-conferring mutations were found. In vitro ALS enzyme assays further confirmed that the SD13 population was resistant to all tested ALS-inhibiting herbicides. The resistance pattern experiments revealed that, compared with SD22, the SD13 population exhibited broad-spectrum resistance to nicosulfuron (43.7-fold), imazethapyr (11.4-fold) and flumetsulam (16.1-fold); however, it did not develop resistance to atrazine, mesotrione and topramezone.

CONCLUSIONS This study demonstrated that Trp574Arg substitution was the main reason for crabgrass resistance to ALS-inhibiting herbicides. To our knowledge, this is the first report of Trp574Arg substitution in a weed species, and is the first report of target-site mechanisms of herbicide resistance for crabgrass.

Oreja, F. H. ; Bastida, F. ; Gonzalez-Andújar, J. L.. 2012. Simulation of control strategies for decision-making regarding Digitaria sanguinalis in glyphosate-resistant soybeans. Ciencia e Investigación Agraria 39 : 299 - 308.

A bioeconomic model was developed for decision-making regarding large crabgrass (Digitaria sanguinalis) control in glyphosate-resistant soybeans in the Rolling Pampas of Argentina. The model was used to evaluate the economic returns of four different glyphosate-based strategies for weed control. In the absence of herbicide application (T1), the soil seed bank increases to an equilibrium density of 12,079 seeds m^-2 in three years. A single herbicide application during the early stages of the crop (T2), which was intended to be highly effective in the control of an early weed cohort, allows a late, unaffected cohort to produce sufficient seeds to maintain population densities in the soil seed bank. A single, delayed herbicide application (T3), which was intended to control both early and late cohorts, results in a soil seed bank increase up to an equilibrium density similar to that achieved without treatment. Two sequential herbicide applications per year (T4), targeting the two cohorts, leads to a soil seed bank density after 10 years of 107 seeds m^-2. Model predictions indicate that in the absence of control measures, a 93% reduction in soybean yield was predicted due to weed interference. The lowest reduction in crop yield (27%) was predicted using strategy T4, which is the most common control measure used by local farmers. This strategy clearly outperforms the other options tested, leading to lower D. sanguinalis seed bank densities and higher soybean yields and economic returns compared to those obtained using the alternative strategies..

Cao HongYu ; Li XiangJu ; Liu ShiYang ; Cui HaiLan ; Niu HongBo. 2011. Study on weed controlling efficiency and safety of glyphosate 41% AS in a transgenic glyphosate-resistant soybean field. Weed Science (China) 29 : 22 - 25.

Weed controlling efficacy and safety of glyphosate 41% AS (aqueous solution) were studied in a field planted with transgenic glyphosate-resistant soybean plants in Beijing, China from May to November in 2010. The glyphosate 41% AS markedly controlled main weeds such as Amaranthus retroflexus, Digitaria sanguinalis, Acalypha australis. The controlling efficacy on weeds was above 90% at 30 days after application of glyphosate 41% AS at 922.5 g a.i./ha. Glyphosate 41% AS was safe to the four herbicide-resistant soybean cultivars (356043, 87701RR2Y, 06-698 and 07 -1568). There were no injuries occurred in the 4 soybean cultivars when glyphosate 41% AS was applied at 922.5-2460.0 g a.i./ha. The plant height, number of compound leaves, number of seeds per pod and 100-seed weight of the 4 cultivars did not tend to decline?The yield of the 4 soybean cultivars with application of glyphosate 41% AS at 922.5-2460.0 g a.i./ha increased significantly than the yield in the absence of application..

Abit, M. J. M. ; Al-Khatib, K. ; Olson, B. L. ; Stahlman, P. W. ; Geier, P. W. ; Thompson, C. R. ; Currie, R. S. ; Schlegel, A. J. ; Holman, J. D. ; Hudson, K. A. ; Shoup, D. E. ; Moechnig, M. J. ; Grichar, W. J. ; Bean, B. W.. 2011. Efficacy of postemergence herbicides tankmixes in aryloxyphenoxypropionate-resistant grain sorghum. Crop Protection 30 : 1623 - 1628.

The development of aryloxyphenoxypropionate (APP)-resistant grain sorghum could provide additional opportunities for postemergence herbicide grass control in grain sorghum. Field experiments were conducted in Texas (Bushland, and Yoakum), Kansas (Dodge City, Garden City, Hays, Manhattan, Colby, Ottawa, and Tribune), and South Dakota (Highmore) to evaluate the efficacy of quizalofop tank mixes in APP-resistant grain sorghum. Quizalofop was applied alone or in combination with dicamba, 2,4-D, prosulfuron, 2,4-D+metsulfuron methyl, or halosulfuron methyl+dicamba. Herbicides were applied when sorghum was 12-50 cm in height. Overall weed control was greater when quizalofop was applied with other herbicides than when applied alone. At 2 and 4 weeks after treatment (WAT), large crabgrass [Digitaria sanguinalis (L.) Scop.], giant foxtail (Setaria faberi Herrm.), and green foxtail [Setaria viridis (L.) Beauv.] control were greater than 90% when quizalofop was applied alone or in combination with dicamba, halosulfuron methyl+dicamba, or prosulfuron. Palmer amaranth (Amaranthus palmeri S. Wats.), puncturevine (Tribulus terrestris L.), and tumble pigweed (Amaranthus albus L.) control were greater than 90% in all treatments except when quizalofop was applied alone. Herbicide treatments, except those that included 2,4-D, caused slight to no sorghum injury. Grain sorghum yield was greater for all herbicide treatments compared to the weedy check. This research showed that application of quizalofop in combination with broadleaf weed herbicides provided excellent weed control in sorghum..

Everman, W. J. ; Mayhew, C. R. ; Burton, J. D. ; York, A. C. ; Wilcut, J. W.. 2009. Absorption, translocation, and metabolism of ¹⁴C-glufosinate in glufosinate-resistant corn, goosegrass (Eleusine indica), large crabgrass (Digitaria sanguinalis), and sicklepod (Senna obtusifolia). Weed Science 57 : 1 - 5.

Greenhouse studies were conducted to evaluate ¹⁴C-glufosinate absorption, translocation, and metabolism in glufosinate-resistant corn, goosegrass, large crabgrass, and sicklepod. Glufosinate-resistant corn plants were treated at the four-leaf stage, whereas goosegrass, large crabgrass, and sicklepod were treated at 5, 7.5, and 10 cm, respectively. All plants were harvested at 1, 6, 24, 48, and 72 h after treatment (HAT). Absorption was less than 20% at all harvest intervals for glufosinate-resistant corn, whereas absorption in goosegrass and large crabgrass increased from approximately 20% 1 HAT to 50 and 76%, respectively, 72 HAT. Absorption of ¹⁴C-glufosinate was greater than 90% 24 HAT in sicklepod. Significant levels of translocation were observed in glufosinate-resistant corn, with ¹⁴C-glufosinate translocated to the region above the treated leaf and the roots up to 41 and 27%, respectively. No significant translocation was detected in any of the weed species at any harvest timing. Metabolites of ¹⁴C-glufosinate were detected in glufosinate-resistant corn and all weed species. Seventy percent of ¹⁴C was attributed to glufosinate metabolites 72 HAT in large crabgrass. Less metabolism was observed for sicklepod, goosegrass, and glufosinate-resistant corn, with metabolites composing less than 45% of detectable radioactivity 72 HAT..

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