WA agronomists have warned that a glyphosate-resistant grass is becoming more common in the Wheatbelt and early action is needed to gain control.
Feathertop Rhodes grass is little known in WA but is becoming more prevalent on roadsides and is beginning to move into paddocks through the spread of its small plentiful seeds.
The grass, which can be easily confused with awnless barnyard grass in its early stages, is a major weed in northern New South Wales and Queensland.
Precision Agronomics agronomist Quenten Knight is based in Esperance and has seen outbreaks along the South Coast Highway between Esperance and Jerramungup.
"It's a pretty vigorous grower and it sets lots of seeds quite early," he said.
"It could end up being a domineering weed, especially in summer."
Mr Knight said early action to control with herbicides before populations increased was the key.
"It's a prime opportunity for growers to be very aware of it and nip it in the bud," he said.
"I just think there isn't much awareness about it."
Feathertop Rhodes grass is a tufted annual grass up to one metre tall with erect and semi-prostrate branched stems capable of rooting at the joints.
Leaf blades are bluish green, 5-25 centimetres long and 3-6 millimetres wide.
The seed-heads or panicles have seven to 19 feathery, white-silver spikes that are 3-9mm long.
The Australian Glyphosate Sustainability Working Group (AGSWG) put out a warning with the Grains Research and Development Corporation (GRDC) earlier this year.
Agronomo consultant and AGSWG member Andrew Storrie said the problem that arose for WA and other states in terms of management was that glyphosate was the chemical of choice for roadside weed management.
He said growers needed to report the existence of the grass to their local shire, but also monitor their own properties where they're allowed to spray and manage any spread.
Australian Herbicide Resistance Initiative (AHRI) leader of communications Peter Newman said feathertop Rhodes grass was on an unwelcome tour of the country, being easily spread by vehicles that stop on the roadside.
"It sets a huge amount of seed per plant that is easily wind dispersed," he said.
"Caravans when they pull over might pick some up and deposit it up the road.
"In the last couple of years we had barely seen it on our roadsides in WA and now it's starting to turn up everywhere."
Mr Newman reported seeing the weed most recently in the Gingin area, but said it is possible the weed was widely populating the Wheatbelt.
The AGSWG is supported by the (GRDC) and key research and development-based crop protection companies with an interest in the sustainability of glyphosate.
The group's website has a range of information about glyphosate resistance including a register of glyphosate resistant weed populations and guides and links for management of glyphosate resistance in different crops and management situations.
p www.glyphosateresistance.org.au for more information.
Rachael Oxborrow
Grains writer for Farm Weekly.
Grains writer for Farm Weekly.
