Department of Agriculture and Food (DAFWA) researchers are surveying hundreds of locations across the grainbelt to examine trends in the incidence and frequency of new and emerging summer weeds.
DAFWA’s survey forms part of a national project funded by the Grains Research and Development Corporation to provide detailed information about emerging summer weed species and herbicide resistance.
DAFWA Principal Research Officer Abul Hashem said weed science staff were revisiting 243 sites sampled last year to assess the prevalence and density of summer weeds, and highlight the variation between years.
“During the 2015 survey, sites were selected approximately every 10 km along the major roads across the WA grainbelt, where weeds were visible on the roadside,” Dr Hashem said.
“The survey identified 91 species at 243 sites throughout the grainbelt.
“The most common species were African lovegrass, fleabane, windmill grass and wild radish.
“African lovegrass was evenly distributed throughout the grainbelt. Fleabane incidence was the greatest in the northern agricultural region, while windmill grass was more prevalent in the central and south-east agricultural regions. Wild radish was most prevalent in the northern and central agricultural regions.”
Dr Hashem said couch was also a major roadside weed in the north and stinking lovegrass in southern agricultural zone of WA.
“Feathertop Rhodes grass, a serious weed in the eastern states, was also regularly found in a few districts in the central and southern agricultural regions.
“Other weeds such as matricaria, stinkwort, roly poly, prickly paddy melon and prickly lettuce were also prevalent on the WA roadside with greater frequency in the central agricultural region.”
Dr Hashem said the roadside surveys helped build a broader picture of potential crop weeds.
“The survey highlighted weed species (fleabane, windmill grass, tar vine, button grass, feathertop Rhodes grass) that are beginning to invade and spread as a result of human activities,” he said.
“Movement of animals, vehicles, soils, wind and water can potentially spread weed seed from one location to another.
“The change in climate is also pushing some weed species from the warmer north to cooler southern agricultural regions.”
During the survey, researchers are also collecting seed samples to test for glyphosate resistance in button grass, tar vine, sow thistle and fleabane.
The Department will repeat the survey in 2017 summer season.
“Weeds on the roadside today are the potential weeds in our crops tomorrow,” he said.
“Summer weeds carry disease, impede crop sowing and utilise stored soil moisture or nutrients that may otherwise be available to the subsequent crop. Identifying summer weeds informs growers of the potential major weed issues in different cropping regions and provides direction for future research on emerging weed species.
“We may require further research on the biology, ecology and management of these weeds to develop an effective control program.”
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