International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
GROUP B/2 RESISTANT SMALLFLOWER UMBRELLA SEDGE
(Cyperus difformis)


ALS inhibitors (B/2)

United States, Arkansas
INTRODUCTION SMALLFLOWER UMBRELLA SEDGE
Smallflower Umbrella Sedge (Cyperus difformis) is a monocot weed in the Cyperaceae family.  In Arkansas this weed first evolved resistance to Group B/2 herbicides in 2010 and infests Rice.   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 halosulfuron-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 Jul 29, 2011 )

Common NameSmallflower Umbrella Sedge
SpeciesCyperus difformis
GroupALS inhibitors (B/2)
Herbicideshalosulfuron-methyl
LocationUnited States, Arkansas
Year2010
Situation(s)Rice
Contributors - (Alphabetically)Jason Norsworthy 
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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse trials comparing a known susceptible Smallflower Umbrella Sedge biotype with this Smallflower Umbrella Sedge 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 Smallflower Umbrella Sedge 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 B/2 resistant Smallflower Umbrella Sedge from Arkansas please update the database.
 
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CONTRIBUTING WEED SCIENTISTS

JASON NORSWORTHY
Professor
University Of Arkansas
Department Of Crop
Soil, And Environmental Sciences
1366 West Altheimer Drive
Williams Hall
Fayetteville, 72704, Arkansas
United States
Email Jason Norsworthy
Web   : Web Site Link

ACKNOWLEDGEMENTS

The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Arkansas have been instrumental in providing you this information. Particular thanks is given to Jason Norsworthy for providing detailed information.
Herbicide Resistant Smallflower Umbrella Sedge Globally
(Cyperus difformis)
Herbicide Resistant Smallflower Umbrella Sedge Globally
(Cyperus difformis)
Drag a column header and drop it here to group by that column
Herbicide Resistant Smallflower Umbrella Sedge Globally
(Cyperus difformis)
#CountryFirstYearSituationActive IngredientsSite of Action
1 Australia (New South Wales ) AustraliaNew South Wales 1994 Rice bensulfuron-methyl 1 ALS inhibitors (B/2)
71Cyperus difformisSmallflower Umbrella Sedge6
2 BrazilBrazil 2000 Rice cyclosulfamuron, and pyrazosulfuron-ethyl 5 ALS inhibitors (B/2)
71Cyperus difformisSmallflower Umbrella Sedge5118
3 GreeceGreece 2009 Rice azimsulfuron, and halosulfuron-methyl 19 ALS inhibitors (B/2)
71Cyperus difformisSmallflower Umbrella Sedge13051
4 ItalyItaly 1999 Rice azimsulfuron, bensulfuron-methyl, and cinosulfuron 24 ALS inhibitors (B/2)
71Cyperus difformisSmallflower Umbrella Sedge5155
5 South KoreaSouth Korea 2002 Rice azimsulfuron, bensulfuron-methyl, cinosulfuron, cyclosulfamuron, ethoxysulfuron, halosulfuron-methyl, imazosulfuron, and pyrazosulfuron-ethyl 27 ALS inhibitors (B/2)
71Cyperus difformisSmallflower Umbrella Sedge152
6 SpainSpain 2000 Rice bensulfuron-methyl, and penoxsulam 38 ALS inhibitors (B/2)
71Cyperus difformisSmallflower Umbrella Sedge5140
7 TurkeyTurkey 2010 Rice azimsulfuron, bensulfuron-methyl, bispyribac-sodium, and penoxsulam 71 ALS inhibitors (B/2)
71Cyperus difformisSmallflower Umbrella Sedge5532
8 United States (California) United StatesCalifornia1993 Rice bensulfuron-methyl 45 ALS inhibitors (B/2)
71Cyperus difformisSmallflower Umbrella Sedge391
9 United States (Arkansas) United StatesArkansas2010 Rice halosulfuron-methyl 45 ALS inhibitors (B/2)
71Cyperus difformisSmallflower Umbrella Sedge5562
10 United States (California) United StatesCalifornia2013 Rice propanil 45 PSII inhibitor (Ureas and amides) (C2/7)
71Cyperus difformisSmallflower Umbrella Sedge6739
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Cite this site as: Heap, I.  The International Survey of Herbicide Resistant Weeds.  Online.  Internet.  Saturday, October 19, 2019 .  Available  www.weedscience.org
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