BRENDON CANT brendon at iinet.net.au
Wed Jul 11 02:02:48 CEST 2007

RESISTANCE MOVEMENT 11.7.07<?xml:namespace prefix = o ns =
"urn:schemas-microsoft-com:office:office" />


University of Western Australia researchers discovered that pollen from
herbicide resistant ryegrass can travel up to 3000 metres due to pollen
drift, confirming WA graingrowers’ fears that herbicide resistance can move
between farms.


Graingrowers should therefore be even more vigilant about herbicide
resistance prevention and management strategies to not only help their own
crops, but their neighbours’ as well.


Preventing herbicide tolerance is responsible farming and means growers won’
t potentially contribute to their neighbours’ chemical bills.


While investigating pollen mediated gene flow and its relationship to
herbicide resistant ryegrass, GRDC supported WA Herbicide Resistance
Initiative (WAHRI) researchers, Dr Roberto Busi and Professor Stephen
Powles, found cross pollination occurred in favourable weather conditions.


Gene flow by pollen in ryegrass leads to highly mobile herbicide resistance,
especially with high rainfall and wind, so strategies are required to
minimise pollen production, dispersal and cross-pollination.


In GRDC supported field trials, plants were sprayed with 15g/ha of
sulfometuron to assess resistance levels and susceptible plants were planted
at varying distances up to 4000 metres from wheat and pasture paddocks
infested with herbicide resistant annual ryegrass plants.


Cross-pollination results in 2005 established that gene flow resistance
occurred by natural movement of resistant pollen over distances of up to
3000 metres.


It was previously thought that ryegrass pollen was only viable within 30
metres of the source plant.


The 2006 study was largely inconclusive due to drought, however the field
experiment will be repeated this year if and when growing conditions


Dr Busi reported that assessing long distance resistance gene flow in
commercial field conditions was critical to understanding the dynamics of
resistance movement.



The Crop Doctor is GRDC Managing Director, Peter Reading, Tel 02 6272 5525

Further Information: Dr Roberto Busi, Tel 08 6488 1423

Professor Stephen Powles, Tel 08 6488 7833

GRDC REF: CDJuly072.doc/Rainbow



Brendon Cant & Associates
Public Relations & Marketing 
Suite 5
4 Gugeri St
Claremont WA 6010
Tel 08 9384 1122

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