Western Australia
October 27, 2017

The bright yellow flowers of matricaria are in full bloom and Western Australian growers are urged to report sightings of this foul smelling weed to determine how far it has spread.


The bright yellow flowers of matricaria are in full bloom. Photo: Kylie Chambers, DPIRD.

The weed is very difficult to control in pasture once it takes hold and spreads quickly thanks to a very large seed bank that can remain viable for five years. 

Research officer Alex Douglas, from the Department of Primary Industries and Regional Development (DPIRD), is studying the biology and control options for matricaria as a part of a five-year project supported by Grains Research and Development Corporation (GRDC) on locally important weeds, including stinking lovegrass, Feathertop Rhodes grass and mallow.

Ms Douglas says matricaria has been reported in areas including Southern Cross, Mukinbudin, Merredin, Kellerberrin and Beacon and there has also been a population found near Esperance.

“We are keen to determine just how widespread matricaria is, and while it is flowering is the perfect time to look out for it,” she said.

“Landholders are encouraged to report any populations of matricaria, especially outside of known areas.”

Ms Douglas said the initial management trials were focused on seed set control options for the pasture phase as an aid to reducing the seed bank. Laboratory and glasshouse research will complement the field work.

“Control options are limited while the plant is flowering, but farmers can note where it was found and be prepared to control it next year when the small plants emerge,” she said.

Preliminary results from field trials (Merredin and Mukinbudin) are showing that time of application of herbicides is critical. 

“Selective herbicides need to be applied to small plants to be most effective and knockdown applications may work best when mixed with other herbicides, to act as a ‘spike’,” Ms Douglas said.

“The best time for applications targeting seed set is likely to be before plants are fully flowering.

“While most matricaria plants die off in early summer after flowering, a few plants may germinate in late winter and continue to grow and produce seed over the summer period, providing conditions are favourable.

"This is becoming more common as the eastern grainbelt experiences more seasons with increased summer rainfall.”

There are two species of matricaria in WA and they can be distinguished by their flower heads. Columba daisy (Oncosiphon suffruticosum) has more ‘club’ shaped flower heads while Globe chamomile (Oncosiphon piluliferum) has rounder, globe shaped flower heads. 

Both varieties of matricaria are annual herbs with bright yellow flowers. They have a strong smell and form dense stands.

Sightings may be reported directly to Alex Douglas on alex.douglas@dpird.wa.gov.au or 0455 067 755, or via the Pestfax Reporter app which is available for Apple and Android. More information can be found at https://www.agric.wa.gov.au/diseases/pestfax-reporter

More information about matricaria is available here http://www.rcsn.net.au/uploads/5/4/2/8/54288593/adouglas-all.pdf

A combined WA distribution map for Columba daisy and Globe chamomile is available at https://florabase.dpaw.wa.gov.au/browse/map/22708

Website: http://www.grdc.com.au

Published: October 27, 2017