<b>HRAC Group 0</b> <font size='2'> (Legacy Z) </font> resistant Nassella trichotoma from Australia, Victoria

INTERNATIONAL HERBICIDE-RESISTANT WEED DATABASE

HRAC GROUP 0 (LEGACY Z) RESISTANT SERRATED TUSSOCK
(Nassella trichotoma)

UnknownHRAC Group 0 (Legacy Z)

Australia, Victoria

INTRODUCTION		SERRATED TUSSOCK
Serrated Tussock (Nassella trichotoma) is a monocot weed in the Poaceae family. In Victoria this weed first evolved resistance to Group 0 (Legacy Z) herbicides in 2002 and infests Pastures. Group 0 (Legacy Z) herbicides are known as Unknown (Unknown). Research has shown that these particular biotypes are resistant to flupropanate and they may be cross-resistant to other Group 0 (Legacy Z) 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 Jul 23, 2003 )
Common Name	Serrated Tussock
Species	Nassella trichotoma
Group	Unknown HRAC Group 0 (Legacy Z)
Herbicides	flupropanate
Location	Australia, Victoria
Year	2002
Situation(s)	Pastures
Contributors - (Alphabetically)	Christopher Preston
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NOTES ABOUT THIS BIOTYPE

GENERAL

Christopher Preston

Flupropanate had been used for 17 years on this pasture. R/S comparison in pot trials conducted twice showed an 8-fold increase in resistance. The local contact for this case is David McLaren (David.McLaren@nre.vic.gov.au)

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ACADEMIC ASPECTS

Confirmation Tests

Greenhouse trials comparing a known susceptible Serrated Tussock biotype with this Serrated Tussock 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 0 resistant Serrated Tussock 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 0 (Legacy Z) resistant Serrated Tussock from Victoria please update the database.

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CONTRIBUTING WEED SCIENTISTS

CHRISTOPHER PRESTON

University Of Adelaide - Waite Campus Crc For Australian Weed Management And School Of Agriculture Box 2146 Adelaide, 5064, South Australia Australia Email Christopher Preston

ACKNOWLEDGEMENTS
The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Victoria have been instrumental in providing you this information. Particular thanks is given to Christopher Preston for providing detailed information.

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Herbicide Resistant Serrated Tussock Globally
(Nassella trichotoma)

Country

FirstYear

Situation

Active Ingredients

Site of Action

Australia (Victoria)

2002

Pastures

flupropanate

Unknown ( HRAC Group 0 (Legacy Z)

Literature about Similar Cases

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Ramasamy, S. ; McLaren, D. A. ; Preston, C. ; Lawrie, A. C.. 2010. Heritability of flupropanate resistance in Nassella trichotoma. : 270 - 273.

Extensive use of flupropanate over the last 20 years has selected for resistance in Nassella trichotoma (serrated tussock) across Australia. To determine its genetic basis, reciprocal crosses were made between resistant and sensitive parents. In the F₁ generation, both sensitive and resistant plants produced seedlings true to type when mated with the same type and 7-10% of the opposite type when mated with the opposite type. The heritability of flupropanate resistance from both the parents suggests a genetic origin. The 80-90% matching of seedling type to maternal parent type strongly indicates mostly a maternal component in the inheritance, with a minor proportion through pollen..

McLaren, D. A. ; Merton, E. ; Pritchard, G. ; Ramasamy, S. ; Grech, C. ; Bonilla, J.. 2008. Evaluating the extent of serrated tussock (Nassella trichotoma) resistance to the herbicide, flupropanate in Australia. : 94 - 96.

Identification of a population of Nassella trichotoma resistant to the herbicide flupropanate just north-west of Melbourne has previously prompted a mail survey of 5000 land managers impacted by N. trichotoma across Australia. Out of 400 respondents, nine reported N. trichotoma resistance to flupropanate and six reported resistance to glyphosate. Follow up testing of suspected properties has now confirmed three properties with N. trichotoma resistance to flupropanate. This study has also developed a relatively quick seed bioassay technique for testing for resistance. The extent of N. trichotoma resistance to flupropanate identified in this survey flags serious concern about its future viability as a management tool. This study emphasises the importance of promoting integrated management of N. trichotoma to help combat resistance..

Ramasamy, S. ; Pritchard, G. ; McLaren, D. A. ; Bonilla, J. ; Preston, C. ; Lawrie, A. C.. 2008. Field survey of flupropanate-resistant Nassella trichotoma in Victoria. : 98 - 100.

A population of Nassella trichotoma (serrated tussock) in Victoria was confirmed as resistant to flupropanate (sodium 2,2,3,3-tetrafluoropropionate) at a property north-west of Melbourne in 2002. To determine the spread of flupropanate resistance, 87 N. trichotoma plants were collected randomly from paddocks and on roadsides within 5 km of the resistant plants in 2003. A pot-dose method of resistance assessment identified plants resistant to flupropanate up to 3.5 km from the site where resistant plants were initially identified. Seeds from these plants showed 0-100% resistance, with sensitive plants often having a low (≤5%) level of resistant seed. These results suggest movement of flupropanate resistance through seeds or pollen and show that its spread had occurred within one year of detection. This research emphasises the importance of integrated weed management and the need to rotate herbicide groups to avoid the risk of resistance..

Verbeek, B. ; Leech, F. ; Ayres, L.. 2004. Glyphosate - another tool for managing serrated tussock (Nassella trichotoma (Nees) Arech.). : 245 - 248.

Land managers had become reliant on the use of the herbicide flupropanate to manage serrated tussock infestations. In 1998, the apparent loss of flupropanate from the market sparked renewed efforts to find other solutions. It also allowed time to reflect on past treatment regimes to determine their effectiveness and limitations. Research into other herbicide options has found that glyphosate was an effective alternative but like flupropanate it had its limitations. In 2004, agricultural advisers are no longer reliant on one herbicide to manage serrated tussock. This is timely given the recent discovery of a population of serrated tussock resistant to flupropanate..

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