Need to beat emerging weeds

Department of Agriculture and Food research officer Dr Mohammad Amjad with a giant button grass plant. Picture: DAFWA

IN the Gingin area, the weed feathertop Rhodes grass has been recorded along Brand Hwy and in some pasture paddocks, according to the Department of Agriculture and Food.

The department said Western Australian grain growers were increasingly battling emerging weeds and would need to employ robust integrated weed management strategies to protect crop yields and profit.

A number of integrated weed management options to control emerging winter and summer weed species will be discussed as part of the Grains Research and Development Corporation’s Grains Research Update in Perth on February 27-28.

A Department of Agriculture and Food roadside survey in 2015 and 2016, as part of integrated weed management research jointly funded with the Grains Research and Development Corporation, found the threat to grains crops from emerging weed species was increasing throughout the grainbelt.

The department’s principal research officer Abul Hashem said the adoption of minimum tillage farming practices, alongside reduced livestock and an increasingly variable climate had encouraged the proliferation of new weed species.

Dr Hashem said summer and winter weeds were being found in bigger populations than previous years.

“For example, out of 246 sites surveyed in 2016, African love grass was found in 87 per cent of sites, windmill grass (61 per cent), fleabane (60 per cent), and wild radish (52 per cent),” he said.

“New species found on the roadsides include sowthistle, button grass and tar vine with 26 per cent, 10 per cent and 7 per cent frequency.”

He said other research projects in the eastern states showed some of the same emerging weed species as in WA had also become increasingly resistant to a number of herbicides, including glyphosate.

With rising incidences of glyphosate resistance, Dr Hashem urged growers with at risk crops to consider a double knockdown to achieve successful weed control and minimise the risk of herbicide resistance development

“If not controlled, the winter weed species compete with crops for soil nutrients and soil moisture, while in summer they remove soil moisture and nutrients.

“It is most important to prevent seed-set of summer and winter weed species to reduce the risk of enriching the weed seed bank in the soil.

“Integrated weed management options for winter weeds species include close row spacing and planting high density crops with a high level of soil disturbance, harvesting low and windrowing and windrow burning or other harvest weed management to reduce the weed seed bank.”