International Survey of Herbicide-Resistant Weeds

Countries Weeds Herbicides Mutations Graphs References Researchers
GROUP B/2 RESISTANT SOAPBUSH
(Clidemia hirta)


ALS inhibitors (B/2)

Malaysia
INTRODUCTION SOAPBUSH
Soapbush (Clidemia hirta) is a dicot weed in the Melastomataceae family.  In Malaysia this weed first evolved resistance to Group B/2 herbicides in 2010 and infests Palm oil.   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 metsulfuron-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 Jan 27, 2014 )

Common NameSoapbush
SpeciesClidemia hirta
GroupALS inhibitors (B/2)
Herbicidesmetsulfuron-methyl
LocationMalaysia
Year2010
Situation(s)Palm oil
Contributors - (Alphabetically)Chuah Tse-Seng 
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NOTES ABOUT THIS BIOTYPE

DOSE RESPONSE

Chuah Tse-Seng

A preliminary report on the potential resistance of a soapbush ('Clidemia hirta' (L.) D. Don) biotype to metsulfuron-methyl in an oil palm plantation in Jerantut, Malaysia

Ramadzan, AMN; Ismail, BS; Chuah, TS

Abstract: The present study was undertaken to confirm the presence of a metsulfuronmethyl resistant (R) biotype of Clidemia hirta (L.) D. Don in an oil palm plantation in Jerantut, compared to a susceptible (S) biotype found in Jengka, Pahang, Malaysia. The first study was conducted as an on-site field spraying experiment using several concentrations of metsulfuron- methyl, whereas the second was carried out in the laboratory using 10 mm diameter leaf discs immersed in several metsulfuron-methyl concentrations. The third study was done in a greenhouse where the growth of the R and S biotypes were observed under two different light intensities. For the on-site field experiment, spraying at the recommended dosage [30 g active ingredient (a.i.) ha-1] gave 100% control of the S biotype, whereas the R biotype showed full recovery (0% control) 56 days after treatment with metsulfuronmethyl at levels as high as eight times (240 g a.i. ha-1) the recommended rate. From the comparison of the ED50 of the leaf discs, the laboratory test showed that the resistant biotype was 16-times more resistant to metsulfuron-methyl than the susceptible biotype. The greenhouse experiment indicated that, relatively, the R biotype expressed slower growth in the upper part growth measurements in plant height, total leaf area, stem mass ratio and relative biomass growth ratio but in contrast, showed greater allocation to root mass compared to S biotype. Both biotypes of C. hirta planted under high light intensity showed slower growth in plant height, relative stem length growth rate, total leaf area, leaf area ratio, leaf mass ratio and stem mass ratio, but allocated more mass to root and relative biomass growth rate.

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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse trials comparing a known susceptible Soapbush biotype with this Soapbush 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 Soapbush 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 Soapbush from Malaysia please update the database.
 
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CONTRIBUTING WEED SCIENTISTS

CHUAH TSE-SENG
Lecturer
Universiti Malaysia Terengganu
Department Of Agrotechnology
Faculty Of Agrotechnology & Food Science
Kuala Terengganu, 21030, Terengganu
Malaysia
Email Chuah Tse-Seng

ACKNOWLEDGEMENTS

The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Malaysia have been instrumental in providing you this information. Particular thanks is given to Chuah Tse-Seng for providing detailed information.
Herbicide Resistant Soapbush Globally
(Clidemia hirta)
Herbicide Resistant Soapbush Globally
(Clidemia hirta)
Drag a column header and drop it here to group by that column
Herbicide Resistant Soapbush Globally
(Clidemia hirta)
#CountryFirstYearSituationActive IngredientsSite of Action
1 MalaysiaMalaysia 2010 Palm oil metsulfuron-methyl 28 ALS inhibitors (B/2)
311Clidemia hirtaSoapbush7876
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Cite this site as: Heap, I.  The International Survey of Herbicide Resistant Weeds.  Online.  Internet.  Sunday, September 22, 2019 .  Available  www.weedscience.org
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