Western Australian grain growers are warned to be on their guard against Feathertop Rhodes grass (FTR), a costly summer weed that has already become a major problem in Australia’s northern cropping region.
Australian Herbicide Resistance Initiative (AHRI) communications leader Peter Newman said the weed had become more prevalent in WA in the last couple of years but was largely not yet ‘on the radar’ of the State’s growers.
It is one of four emerging weeds in WA being investigated under a new Grains Research and Development Corporation (GRDC) funded project ‘Locally Important Weeds’, led in WA by Department of Agriculture and Food (DAFWA) researcher Alex Douglas.
The project also involves the University of Adelaide and CSIRO carrying out research into emerging weeds in Australia’s southern cropping region. (Click here for more details about this project).
FTR (Chloris virgata) is a tufted annual grass growing up to one-metre tall, and has a distinctive seed head of between seven and 19 feathery spikes.
Mr Newman, whose work at AHRI is supported by the GRDC, said there were currently isolated outbreaks of FTR in different parts of the WA grainbelt, especially on roadsides, and it was important that the weed was not allowed to get a foothold in the State’s cropping systems.
“It is really important that growers know what this weed looks like and that they act straight away to eradicate any populations from their paddocks,” he said.
“It is also necessary to find the source – which can often be on roadsides – and notify relevant local authorities so they can control it,” he said.
“FTR is problematic as it is difficult to control – it is relatively tolerant to glyphosate, especially after early tillering.”
Populations of FTR have been confirmed resistant to glyphosate in New South Wales, Queensland and South Australia.
Resources to assist the sustainable use of glyphosate in Australian agriculture are available on the Australian Glyphosate Sustainability Working Group website
Information about managing FTR is available in the GRDC Fact Sheet Managing feathertop Rhodes grass.
It states that FTR is quick to mature and can produce seed heads within four weeks if conditions are suitable, and that major flushes occur when good rain falls over consecutive days, particularly in spring.
“Glyphosate (Group M) alone may be ineffective on FTR regardless of the age of the weed,” the fact sheet states.
“However, if paraquat (Group L) is applied sequentially in a double knock, control is improved, although 100 per cent control is rarely achieved.”
As part of the GRDC-funded project ‘Improving IWM practice of emerging weeds in the southern and western region’, conducted with Chris Preston of the University of Adelaide, DAFWA collected seed of several WA FTR populations during a roadside survey of summer weeds in 2015.
Herbicide resistance testing is now being conducted on these populations by DAFWA at Northam.
DAFWA researcher Abul Hashem said that during the roadside survey for emerging weeds, 242 sites were sampled in 2015 and 138 sites in 2016 - to assess the prevalence and density of summer weeds and highlight the variation between years.
“Several FTR populations were found in large infestations in the Lake Grace area, eastern grainbelt and Gingin area, including one population in a pasture paddock,” he said.
However, growers in other parts of the WA grainbelt are also advised to be on the look-out for FTR which has been reported in additional areas including Borden, Albany and Cunderdin.
Dr Hashem said the roadside surveys from both years have revealed that African love grass, fleabane, windmill grass and wild radish are the most widely distributed summer weed species in WA.
“Other summer weeds such as couch, sowthistle and stink grass were also found to be common in some regions,” he said
Dr Hashem said the movement of animals, vehicles, soils, wind and water could potentially spread weed seed from one location to another, and the change in climate was also pushing some weed species from the warmer north to cooler southern agricultural regions.
Peter Newman, Planfarm/AHRI
08 9964 1170, 0427 984 010
Abul Hashem, DAFWA
08 9690 2136
Natalie Lee, Cox Inall Communications
08 9864 2034, 0427 189 827