International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
(Alopecurus aequalis)

ALS inhibitors (B/2)

Japan, Fukuoka
Shortawn Foxtail (Alopecurus aequalis) is a monocot weed in the Poaceae family.  In Japan this weed first evolved resistance to Group B/2 herbicides in 2006 and infests Wheat.   Group B/2 herbicides are known as ALS inhibitors (Inhibition of acetolactate synthase ALS (acetohydroxyacid synthase AHAS)).  Research has shown that these particular biotypes are resistant to thifensulfuron-methyl and they may be cross-resistant to other Group B/2 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 Feb 04, 2016 )

Common NameShortawn Foxtail
SpeciesAlopecurus aequalis
GroupALS inhibitors (B/2)
LocationJapan, Fukuoka
Contributors - (Alphabetically)Akira Uchino 
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Akira Uchino

Journal of Weed Science and Technology
Vol. 59 (2014) No. 3 p. 157-166

Occurrence of herbicide resistant biotypes of Alopecurus aequalis in northern Kyushu and their response to several herbicides
Hideki Ohdan, Tadashi Sumiyoshi, Akira Koarai 

This study was conducted to confirm the occurrence and distribution of trifluralin (TR)- and thifensulfuron methyl (TM)-resistant biotypes of Alopecurus aequalis in northern Kyushu and their 
response to several herbicides. Seeds were collected from wheat and barley fields in Fukuoka, Saga, Nagasaki, Kumamoto, and Oita Prefectures and tested for susceptibility to two herbicides. Consequently, three biotypes of TR-resistant, TM-resistant, and multiple-resistant biotypes were confirmed, and it was found that herbicide-resistant biotypes were widely distributed in this area. The R/S ratio of multiple-resistant biotypes collected in Asakura, Fukuoka Prefecture, was 13.1 for TR, and showed cross-resistance against pendimethalin. This biotype showed no mortality when treated at the 4–5 leaf stage with TM at a concentration four 
times higher. Herbicides containing benthiocarb demonstrated 
effective control against this biotype. Therefore, it is suggested that thiocarbamate herbicides are effective in controlling TR and/or TM resistant biotypes of A. aequalis.​

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Confirmation Tests

Greenhouse, and Laboratory trials comparing a known susceptible Shortawn Foxtail biotype with this Shortawn Foxtail 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 Group B/2 resistant Shortawn Foxtail 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 B/2 resistant Shortawn Foxtail from Japan 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 B/2 resistant Shortawn Foxtail from Japan please update the database.
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Weed Scientist
NARO Agricultural Research Center
3-1-1 Kannondai
Tsukuba, 305-8666, Ibaraki
Email Akira Uchino


The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Japan have been instrumental in providing you this information. Particular thanks is given to Akira Uchino for providing detailed information.
Herbicide Resistant Shortawn Foxtail Globally
(Alopecurus aequalis)
Herbicide Resistant Shortawn Foxtail Globally
(Alopecurus aequalis)
Drag a column header and drop it here to group by that column
Herbicide Resistant Shortawn Foxtail Globally
(Alopecurus aequalis)
#CountryFirstYearSituationActive IngredientsSite of Action
1 ChinaChina 2010 Wheat clodinafop-propargyl, and fenoxaprop-P-ethyl 9 ACCase inhibitors (A/1)
264Alopecurus aequalisShortawn Foxtail5524
2 ChinaChina 2014 Wheat fenoxaprop-P-ethyl, flucarbazone-sodium, mesosulfuron-methyl, nicosulfuron, penoxsulam, pinoxaden, and quizalofop-P-ethyl 9 Multiple Resistance: 2 Sites of Action
ACCase inhibitors (A/1)
ALS inhibitors (B/2)
264Alopecurus aequalisShortawn Foxtail10954
3 JapanJapan 2004 Spring Barley, and Wheat thifensulfuron-methyl, and trifluralin 25 Multiple Resistance: 2 Sites of Action
ALS inhibitors (B/2)
Microtubule inhibitors (K1/3)
264Alopecurus aequalisShortawn Foxtail5570
4 JapanJapan 2005 Wheat, and Winter barley trifluralin 25 Microtubule inhibitors (K1/3)
264Alopecurus aequalisShortawn Foxtail11018
5 JapanJapan 2006 Wheat thifensulfuron-methyl 25 ALS inhibitors (B/2)
264Alopecurus aequalisShortawn Foxtail11019
Literature about Similar Cases

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