<b>HRAC Group 2</b> <font size='2'> (Legacy B) </font> resistant Damasonium minus from Australia, New South Wales

International Survey of Herbicide-Resistant Weeds

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Thursday, October 31, 2024

HRAC GROUP 2 (LEGACY B) RESISTANT STARFRUIT
(Damasonium minus)

Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)

Australia, New South Wales

INTRODUCTION		STARFRUIT
Starfruit (Damasonium minus) is a monocot weed in the Alismataceae family. In New South Wales this weed first evolved resistance to Group 2 (Legacy B) herbicides in 1994 and infests Rice. Group 2 (Legacy B) herbicides are known as Inhibition of Acetolactate Synthase (Inhibition of Acetolactate Synthase ). Research has shown that these particular biotypes are resistant to bensulfuron-methyl and they may be cross-resistant to other Group 2 (Legacy B) 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.

QUIK STATS (last updated Jun 06, 2000 )
Common Name	Starfruit
Species	Damasonium minus
Group	Inhibition of Acetolactate Synthase HRAC Group 2 (Legacy B)
Herbicides	bensulfuron-methyl
Location	Australia, New South Wales
Year	1994
Situation(s)	Rice
Contributors - (Alphabetically)	Jim Pratley, and Andrew Storrie
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NOTES ABOUT THIS BIOTYPE

AREAS FOUND

Andrew Storrie

Irrigation areas of southern NSW.

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GENERAL

Andrew Storrie

No replacement chemicals for bensulfuron.

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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse trials comparing a known susceptible Starfruit biotype with this Starfruit 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 HRAC Group 2 resistant Starfruit 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 2 (Legacy B) resistant Starfruit from New South Wales please update the database.

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CONTRIBUTING WEED SCIENTISTS

JIM PRATLEY

Dean, Faculty Of Science & Agriculture Charles Sturt University School Of Agriculture Dept of Crop& Soil Sciences PO Box 646420, Wagga Wagga, 2678, New South Wales Australia Email Jim Pratley

ANDREW STORRIE

Principal Agronomo School Of Agriculture Po Box 5444 Albany, 6332, Western Australia Australia Email Andrew Storrie Web : Web Site Link

ACKNOWLEDGEMENTS
The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in New South Wales have been instrumental in providing you this information. Particular thanks is given to Jim Pratley, and Andrew Storrie for providing detailed information.

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Herbicide Resistant Starfruit Globally
(Damasonium minus)

Country

FirstYear

Situation

Active Ingredients

Site of Action

Australia (New South Wales )

1994

Rice

bensulfuron-methyl

Inhibition of Acetolactate Synthase ( HRAC Group 2 (Legacy B)

Literature about Similar Cases

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Broster, J. C. ; Pratley, J. E. ; Flower, G. E. ; Flower, R.. 2004. Determining the extent of herbicide resistance in the rice growing regions of southern Australia. : 406 - 409.

Weed seed samples were collected from across the rice growing regions of southern New South Wales, Australia and tested against a relevant range of commercial herbicides (bensulfuron, thiobencarb, benzofenap, MCPA, propanil, clomazone and molinate) to establish benchmark levels of resistance for each weed and herbicide combination. Approximately 50% of dirty Dora (Cyperus difformis), 40% of starfruit (Damasonium minus) and 38% of arrowhead (Sagittaria montevidensis) samples were resistant to bensulfuron. All dirty Dora, arrowhead and starfruit samples were susceptible to all the other herbicides tested. No barnyard grass samples were resistant to any of herbicides tested. A total of 6 barnyard grass species (barnyard grass (Echinochloa crus-galli), awnless barnyard grass (E. colona), hairy millet (E. oryzoides), prickly barnyard grass (E. microstachya), Japanese millet (E. esculenta) and channel millet (E. inundata)) were detected. Four species were collected during the first survey and 5 in the second. Three of the 6 species were present in both surveys. In a number of the samples, 2 different species were present. These species had slightly different rates of germination, resulting in slightly different growth stages of the weeds at the time of herbicide application. Where mixed populations occur in the field, this is of major importance when dealing with any herbicides that have a narrow range of growth stages for effective application. At present, herbicide resistance in weeds of rice appears to be confined to bensulfuron. However it remains important for farmers to implement appropriate herbicide resistance management to protect the viability of the herbicide options..

Jahromi, F. G. ; Ash, G. J. ; Cother, E. J.. 2002. Genetic variability identified in populations of the rice weed starfruit (Damasonium minus) by simple sequence repeats. Plant Protection Quarterly 17 : 151 - 154.

Starfruit (Damasonium minus) is one the most important weeds of rice in Australia and has developed resistance to the main herbicide (bensulfuron-methyl) used for its control. A fungal pathogen, Rhynchosporium alismatis, is being investigated as a biological control agent for the integrated management of this weed. The genetic variability of populations of a weed may influence the success of this approach to its control. The variability of starfruit populations was compared at the molecular level using simple sequence repeats (SSRs). Forty-seven individual starfruit plants originating from seeds harvested from 18 locations across the rice-growing areas were used. The small patterns of variability between samples did not always relate to their geographic locations. As little variability was found it could be expected that the disease caused by the biological control agent would be the same across different weed populations. The agronomy, rather than genetic variability, of the weed may be the cause of its variable response to herbicides across rice-growing regions..

Pratley, J. ; Broster, J. ; Flower, G. ; Flower, R.. 2002. Determining the extent of herbicide resistance in the rice growing regions of southern Australia. Farmers' Newsletter : 48 - 49.

The resistance of some rice weeds, dirty dora (Cyperus difformis), starfruit (Damasonium minus), arrowhead (Sagittaria montevidensis) and barnyardgrass (Echinochloa crus-galli), to bensulfuron (Londax; 600 g a.i./kg), thiobencarb (Saturn; 800 g a.i./litre), benzofenap (Taipan; 300 g a.i./litre), MCPA (250 g a.i./litre), propanil (Ronacil; 360 g a.i./ha), clomazone (Command or Magister; 600 g a.i./litre) and molinate (Ordram; 860 g a.i./ha) was determined in fields in Australia [date not given]. He weeds were resistant only to bensulfuron. Bensulfuron was classified as having high risk of herbicide resistance development, MCPA as having low risk, and all the others as having moderate risk..

Jahromi, F. G. ; Ash, G. J. ; Cother, E. J.. 1997. Suppressive effects of Rhynchosporium alismatis on different growth stages of Damasonium minus. : 195 - 198.

Starfruit (Damasonium minus) is one of the most important weeds in Australian rice fields. This weed is resistant to bensulfuron-methyl. A study was carried out to evaluate the application of a mycoherbicide comprising Rhynchosporium alismatis (which causes necrosis and chlorosis on leaves) on plants at different growth stages. The effect of the conidial suspension after 2 weeks was a significant reduction of green leaf area, when applied to starfruits with 2 or more floating leaves. Significant reduction in green biomass was also observed in inoculated plants with more than 4 floating leaves..

Graham, R. J. ; Pratley, J. E. ; Slater, P. D. ; Baines, P. R.. 1996. Herbicide resistant aquatic weeds, a problem in New South Wales rice crops. : 156 - 158.

A survey was conducted of New South Wales (NSW) rice farms where bensulfuron had been extensively used. Seeds of the aquatic weed species, starfruit (Damasonium minus R.Br. Buch.), dirty dora (Cyperus difformis) and arrowhead (Saggitaria montevidensis Cham. & Schlechter) were collected and screened in pots for resistance to bensulfuron. Resistance was detected in all three species. Two of the five D. minus samples screened in the survey exhibited resistance. Only one of the 17 C. difformis samples analysed was clearly susceptible whilst two of the six S. montevidensis samples examined were resistant. Many additional samples of these three species, obtained subsequent to this survey and processed by the resistance testing service at Charles Sturt University (CSU) have also proven to be resistant. These findings have widespread and serious implications for the rice industry. The current lack of aquatic weed management options means that Riverina rice farmers are being confronted with a problem which currently has few viable solutions..

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