International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
(Urochloa panicoides)

Photosystem II inhibitors (C1/5)

Australia, Queensland
Liverseedgrass (Urochloa panicoides) is a monocot weed in the Poaceae family.  In Queensland this weed first evolved resistance to Group C1/5 herbicides in 1996 and infests Cropland.   Group C1/5 herbicides are known as Photosystem II inhibitors (Inhibition of photosynthesis at photosystem II).  Research has shown that these particular biotypes are resistant to atrazine and they may be cross-resistant to other Group C1/5 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 Jun 06, 2000 )

Common NameLiverseedgrass
SpeciesUrochloa panicoides
GroupPhotosystem II inhibitors (C1/5)
LocationAustralia, Queensland
Contributors - (Alphabetically)Steve Walker 
Edit this Case  |  Add New Case of Resistance  |  Add Note


Confirmation Tests

Greenhouse trials comparing a known susceptible Liverseedgrass biotype with this Liverseedgrass 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 C1/5 resistant Liverseedgrass 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

Triazine resistant weeds often exhibit a lower relative fitness when compared to susceptible biotypes.  The most common mutation conferring triazine resistance (Ser 264 to Gly mutation of the psbA gene) also causes a reduction in CO2 fixation, quantum yield, and seed and biomass production.  There is no record in this database referring specifically to fitness studies on Group C1/5 resistant Liverseedgrass from Queensland.
Edit Case  |  Add Note  |  Add Article  |  Add New Case  |  Help


Principal Agronomist
Farming Systems Institute, Qdpi
Leslie Research Centre
303 North Roberts
PO Box 200201,
Toowoomba, 4350, Queensland
Email Steve Walker


The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Queensland have been instrumental in providing you this information. Particular thanks is given to Steve Walker for providing detailed information.
Herbicide Resistant Liverseedgrass Globally
(Urochloa panicoides)
Herbicide Resistant Liverseedgrass Globally
(Urochloa panicoides)
Drag a column header and drop it here to group by that column
Herbicide Resistant Liverseedgrass Globally
(Urochloa panicoides)
#CountryFirstYearSituationActive IngredientsSite of Action
1 ArgentinaArgentina 2017 Corn (maize), and Soybean glyphosate 48 EPSP synthase inhibitors (G/9)
171Urochloa panicoidesLiverseedgrass18158
2 Australia (Queensland) AustraliaQueensland1996 Cropland atrazine 1 Photosystem II inhibitors (C1/5)
171Urochloa panicoidesLiverseedgrass530
3 Australia (New South Wales ) AustraliaNew South Wales 2008 Sorghum, and Wheat glyphosate 1 EPSP synthase inhibitors (G/9)
171Urochloa panicoidesLiverseedgrass5362
Literature about Similar Cases

Page size:
Page: of 2
Items 1 to 5 of 7

Page size:
Page: of 2
Items 1 to 5 of 7
PERMISSION MUST BE OBTAINED FIRST if you intend to base a significant portion of a scientific paper on data derived from this site.
Cite this site as: Heap, I.  The International Survey of Herbicide Resistant Weeds.  Online.  Internet.  Saturday, January 23, 2021 .  Available
Copyright © 1993- 2021 All rights reserved. Fair use of this material is encouraged. Proper citation is requested.