International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
(Chloris barbata = (C. inflate))

PSII inhibitor (Ureas and amides) (C2/7)

United States, Hawaii
Swollen Fingergrass (Chloris barbata = (C. inflate)) is a monocot weed in the Poaceae family.  In Hawaii this weed first evolved resistance to Group C2/7 herbicides in 1987 and infests Roadsides, and Sugarcane for sugar.   Group C2/7 herbicides are known as PSII inhibitor (Ureas and amides) (Inhibition of photosynthesis at photosystem II).  Research has shown that these particular biotypes are resistant to diuron and they may be cross-resistant to other Group C2/7 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.

If we do not have a picture for this weed, or you can provide a better picture (scan, digital camera etc) please please e-mail it to us.

QUIK STATS (last updated Sep 15, 2000 )

Common NameSwollen Fingergrass
SpeciesChloris barbata = (C. inflate)
GroupPSII inhibitor (Ureas and amides) (C2/7)
LocationUnited States, Hawaii
Situation(s)Roadsides, and Sugarcane for sugar
Contributors - (Alphabetically)Lance Santo 
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Lance Santo
Maui, Honolulu, and Kauai counties.

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Lance Santo
Resistance 1st observed on field edges. Seeds from the field edges moved into the fields in the following crop by wind, tillage, and water.

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Confirmation Tests

Field, and Greenhouse trials comparing a known susceptible Swollen Fingergrass biotype with this Swollen Fingergrass 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 C2/7 resistant Swollen Fingergrass 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 C2/7 resistant Swollen Fingergrass from Hawaii please update the database.
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Agronomist/Field Coordinator
Hawaii Agriculture Research Center
Pesticide And Residue
94-340 Kunia Road
Waipahu, 96797, Hawaii
United States
Email Lance Santo
Web   : Web Site Link


The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Hawaii have been instrumental in providing you this information. Particular thanks is given to Lance Santo for providing detailed information.
Herbicide Resistant Swollen Fingergrass Globally
(Chloris barbata = (C. inflate))
Herbicide Resistant Swollen Fingergrass Globally
(Chloris barbata = (C. inflate))
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Herbicide Resistant Swollen Fingergrass Globally
(Chloris barbata = (C. inflate))
#CountryFirstYearSituationActive IngredientsSite of Action
1 MexicoMexico 2018 Oranges glyphosate 29 EPSP synthase inhibitors (G/9)
53Chloris barbata = (C. inflate)Swollen Fingergrass18197
2 United States (Hawaii) United StatesHawaii1987 Roadsides, and Sugarcane for sugar ametryn 45 Photosystem II inhibitors (C1/5)
53Chloris barbata = (C. inflate)Swollen Fingergrass227
3 United States (Hawaii) United StatesHawaii1987 Roadsides, and Sugarcane for sugar diuron 45 PSII inhibitor (Ureas and amides) (C2/7)
53Chloris barbata = (C. inflate)Swollen Fingergrass228
Literature about Similar Cases

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Cite this site as: Heap, I.  The International Survey of Herbicide Resistant Weeds.  Online.  Internet.  Wednesday, August 5, 2020 .  Available
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