International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
GROUP B/2 RESISTANT SILKY WINDGRASS
(Apera spica-venti)


ALS inhibitors (B/2)

Latvia, Riga
INTRODUCTION SILKY WINDGRASS
Silky Windgrass (Apera spica-venti) is a monocot weed in the Poaceae family.  In Latvia this weed first evolved resistance to Group B/2 herbicides in 2015 and infests Wheat, and Winter 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 iodosulfuron-methyl-sodium 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 Mar 08, 2017 )

Common NameSilky Windgrass
SpeciesApera spica-venti
GroupALS inhibitors (B/2)
Herbicidesiodosulfuron-methyl-sodium
LocationLatvia, Riga
Year2015
Situation(s)Wheat, and Winter wheat
Contributors - (Alphabetically)Jevgenija Necajeva 
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NOTES ABOUT THIS BIOTYPE

GENERAL

Jevgenija Necajeva

Apera spica-venti L. (common wind-grass / loose silky-bent) with ALS inhibitor Resistance in Latvia

Apera spica-venti L. is a monocotyledonous weed species, widespread in the entire territory of Latvia, mostly occurs in winter cereals. ALS inhibitors (B group according to HRAC classification) are the most commonly applied herbicides in Latvia, often B group herbicides are applied repeatedly (repeatedly in two years in 40% fields surveyed in the time period 2013-2015). Seed samples were collected in two locations in 2015. Resistance was tested in a greenhouse trial in one case and in a molecular test for TSR-related mutations in the other case. Greenhouse trial showed reduced efficacy (75-80%) of the full recommended dose of iodosulfuron-methyl-sodium. In the field where resistance was confirmed ALS inhibitors were applied in 4 years in the time period from 2011 to 2015.

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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse, and Laboratory trials comparing a known susceptible Silky Windgrass biotype with this Silky Windgrass 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 Group B/2 resistant Silky Windgrass 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 Silky Windgrass from Latvia 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 Silky Windgrass from Latvia please update the database.
 
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CONTRIBUTING WEED SCIENTISTS

JEVGENIJA NECAJEVA
Research Scientist
University of Latvia
Department of Plant Physiology
1 Jelgavas Street
Riga, Riga
Latvia
Email Jevgenija Necajeva

ACKNOWLEDGEMENTS

The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Latvia have been instrumental in providing you this information. Particular thanks is given to Jevgenija Necajeva for providing detailed information.
Herbicide Resistant Silky Windgrass Globally
(Apera spica-venti)
Herbicide Resistant Silky Windgrass Globally
(Apera spica-venti)
Drag a column header and drop it here to group by that column
Herbicide Resistant Silky Windgrass Globally
(Apera spica-venti)
#CountryFirstYearSituationActive IngredientsSite of Action
1 AustriaAustria 2009 Cereals iodosulfuron-methyl-sodium, and isoproturon 2 Multiple Resistance: 2 Sites of Action
ALS inhibitors (B/2)
PSII inhibitor (Ureas and amides) (C2/7)
20Apera spica-ventiSilky Windgrass6746
2 Czech RepublicCzech Republic 2005 Cereals, and Winter wheat chlorsulfuron, iodosulfuron-methyl-sodium, isoproturon, mesosulfuron-methyl, pyroxsulam, and sulfosulfuron 12 Multiple Resistance: 2 Sites of Action
ALS inhibitors (B/2)
PSII inhibitor (Ureas and amides) (C2/7)
20Apera spica-ventiSilky Windgrass5266
3 DenmarkDenmark 2011 Winter wheat iodosulfuron-methyl-sodium, and sulfosulfuron 13 ALS inhibitors (B/2)
20Apera spica-ventiSilky Windgrass5674
4 FranceFrance 2006 Wheat iodosulfuron-methyl-sodium, mesosulfuron-methyl, and pyroxsulam 17 ALS inhibitors (B/2)
20Apera spica-ventiSilky Windgrass9936
5 GermanyGermany 1997 Cereals, and Winter wheat isoproturon 18 PSII inhibitor (Ureas and amides) (C2/7)
20Apera spica-ventiSilky Windgrass5026
6 GermanyGermany 2005 Wheat chlorsulfuron, florasulam, flupyrsulfuron-methyl-sodium, iodosulfuron-methyl-sodium, mesosulfuron-methyl, pyroxsulam, sulfometuron-methyl, and sulfosulfuron 18 ALS inhibitors (B/2)
20Apera spica-ventiSilky Windgrass5526
7 GermanyGermany 2009 Spring Barley, and Winter wheat fenoxaprop-P-ethyl, iodosulfuron-methyl-sodium, isoproturon, mesosulfuron-methyl, pinoxaden, pyroxsulam, and sulfosulfuron 18 Multiple Resistance: 3 Sites of Action
ACCase inhibitors (A/1)
ALS inhibitors (B/2)
PSII inhibitor (Ureas and amides) (C2/7)
20Apera spica-ventiSilky Windgrass5410
8 LatviaLatvia 2015 Wheat, and Winter wheat iodosulfuron-methyl-sodium 174 ALS inhibitors (B/2)
20Apera spica-ventiSilky Windgrass15067
9 LithuaniaLithuania 2013 Winter wheat iodosulfuron-methyl-sodium 185 ALS inhibitors (B/2)
20Apera spica-ventiSilky Windgrass7821
10 PolandPoland 2005 Winter wheat chlorsulfuron, iodosulfuron-methyl-sodium, procarbazone-sodium, and sulfosulfuron 33 ALS inhibitors (B/2)
20Apera spica-ventiSilky Windgrass5395
11 PolandPoland 2010 Winter wheat fenoxaprop-P-ethyl, and pinoxaden 33 ACCase inhibitors (A/1)
20Apera spica-ventiSilky Windgrass5619
12 PolandPoland 2011 Winter wheat chlorsulfuron, fenoxaprop-P-ethyl, pinoxaden, sulfometuron-methyl, and sulfosulfuron 33 Multiple Resistance: 2 Sites of Action
ACCase inhibitors (A/1)
ALS inhibitors (B/2)
20Apera spica-ventiSilky Windgrass6758
13 PolandPoland 2012 Winter wheat isoproturon 33 PSII inhibitor (Ureas and amides) (C2/7)
20Apera spica-ventiSilky Windgrass6759
14 SwedenSweden 2006 Winter wheat isoproturon 40 PSII inhibitor (Ureas and amides) (C2/7)
20Apera spica-ventiSilky Windgrass10996
15 SwedenSweden 2010 Winter wheat iodosulfuron-methyl-sodium, and sulfosulfuron 40 ALS inhibitors (B/2)
20Apera spica-ventiSilky Windgrass10994
16 SwitzerlandSwitzerland 1994 Wheat isoproturon 41 PSII inhibitor (Ureas and amides) (C2/7)
20Apera spica-ventiSilky Windgrass208
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