News & Media

Research to knock down threat from emerging weeds

Released on

Released on:
Friday, 12. June 2020 - 10:00

A collection of management packages are being developed to control four weeds in Western Australia that are emerging as major threats to agricultural production.

Matricaria, stinking love grass, marshmallow and Feathertop Rhodes grass are found in various areas across the grainbelt, with Feathertop Rhodes grass occurring on the side of many major roads.

The Department of Primary Industries and Regional Development is undertaking the final year of a five year research project to better understand and control these weeds, with co-investment from the Grains Research and Development Corporation.

Project leader, research scientist Alex Douglas, has been examining the biology of the weeds to develop integrated weed control management strategies.

“Relatively little was known about these weeds and how they respond to herbicides and other typical control measures,” she said.

“While not currently widespread, these weeds can be a threat to crops and pastures, as they use soil nutrients and soil moisture required for crop establishment and yield optimisation.

“Field and glasshouse research trials were employed to understand these weeds’ characteristics and growth so we can identify the most effective treatments and strategies to stop them from spreading.”

A fact sheet is currently being developed for matricaria, a smelly, winter growing weed with yellow ball flowers found across the eastern grainbelt.

Ms Douglas said that while matricaria was first noted in the eastern grainbelt in the 1960s, it has proliferated since the advent of reduced tillage practices in the 1990s, less livestock, bigger farms and a changing climate.

“This broadleaf weed has a pungent odour that smells like a cross between football socks and cat wee,” she said.

“Sheep do not like to eat it so it is best controlled by a selective broadleaf herbicide.

“Field trials demonstrate that the timing of the herbicide treatments is crucial.

“The research has also found selective herbicides are best applied to small plants, while, in fallow situations, a knockdown is preferable when mixed with other herbicides to act as a ‘spike’.”

Marshmallow is a winter weed, sometimes found in summer, which has proliferated through the grainbelt with the advent of minimum tillage paddock practices.

“Marshmallow seeds are woody and as a result can survive in the soil for a number of years until conditions are right for germination,” Ms Douglas said.

“There are some residual herbicides that may extend the effective control period for marshmallow in specific crops.”

Stinking love grass is another aromatic summer weed found in the eastern and northern grainbelt.

“Stink grass, as it is sometimes shortened to, is not toxic and can be eaten by sheep when young as a management measure,” Ms Douglas said.

“Grass selective herbicides are effective in controlling stinking lovegrass, as well as the knockdown herbicides, glyphosate and paraquat.”

Feathertop Rhodes grass is a common summer weed that grows alongside many major Western Australian regional roadsides, from Esperance to Geraldton.

“Seed survival studies have shown a high level of germination and low levels of dormancy,” Ms Douglas said.

“Sheep love it, providing an effective non-chemical management option – if the landholders have livestock.

“This could be useful, as trials have shown some resistance to glyphosate and some selective herbicides, which could increase the risk to crop and pasture production.”

The department has also been collaborating with the CSIRO on development of a new summer weed management tool, at a national level.

As the project commences its final year, a series of Paddock Practices factsheets will be produced to assist landholders manage these weeds and minimise their impact on production and the environment.

Ms Douglas urged landholders to support the research by contributing to the department’s PestFax service by photographing and reporting these and other unusual weeds on their properties.

“It is important to know what weeds you have on your property and where they are so integrated weed management strategies can be employed to minimise their impact on crops, pastures and the environment,” she said.

“Contributing to PestFax will assist the department to continually refine its research and advice, while landholders can also seek further advice via the app.”

The department’s PestFax Reporter app is available for free for Apple and Android devices.


Yellow flowers
Matricaria might look pretty but it is a smelly, invasive winter plant found across the eastern grainbelt that is part of a DPIRD research project into currently minor weeds that could emerge further to threaten agricultural production.

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Jodie Thomson/Megan Broad, media liaison                            

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