Dr Ali Bajwa, Weed Scientist, La Trobe University, The Buloke Times

Gazanias, a popular groundcover plant, are increasingly invading cropping paddocks in South Australia and Victoria.

Dr. Ali Bajwa of La Trobe University is studying their spread and control methods under the GRDC’s National Grower Network. Two main species exist in Australia, with interbreeding complicating management.

What have you observed during the survey and preliminary weed ecology studies?

Surveys identified major gazania infestations in cropping areas like the Mallee region and South Australia’s Yorke and Eyre peninsulas. Data from over 800 sites showed significant variability in plant characteristics, adding complexity to management. Gazania seeds have high germination rates (up to 95 per cent) and can tolerate high soil salinity, making them resilient invaders.

Are there any effective herbicide options growers can deploy?

There are no registered herbicides for gazania, as their waxy leaves resist uptake. Trials in a glasshouse showed that early-stage plants (3 leaves) were most susceptible, with effectiveness dropping as plants matured. Field trials in South Australia are testing potential control options.

What other strategies can growers implement?

Until effective herbicides are identified, growers can use high-dose knockdown herbicides with spot sprayers during summer fallow. Cultivation may help by burying seeds and inducing germination before applying herbicide at the early growth stage. Further research is needed to develop comprehensive control strategies.

For a comprehensive understanding of the challenges posed by gazania infestations in South Australia’s cropping paddocks and the ongoing research efforts to manage this resilient weed, you can read the full article titled “Gazania Wars: 5 Things You Need to Know About Tackling a Persistent Weed” published by Mallee Sustainable Farming.

This article appeared in The Buloke Times, 25 March 2025.