Crop weeds

Weeds are estimated to cost Australian agriculture more than $2.5 billion per year. Understanding weeds and the various methods to control them ultimately reduces costs and improves productivity.

The Department of Primary Industries and Regional Development conducts research into the management of weeds and has developed integrated weed management (IWM) packages, that incorporate a number of varied weed control options, including chemical, physical and biological strategies, are vital for sustainable weed management in this state.

Weed populations that have developed herbicide resistance, where standard herbicide treatments are no longer effective, pose an increasing threat to WA's agricultural production.


  • Four summer weed time of removal trials were implemented across the Western Australian wheatbelt in March 2017 following a widespread summer rainfall event.

  • The term 'residual' applies to a number of herbicides that have a long lasting activity in the soil. These herbicides are often applied directly to the soil prior to planting crops, pre-emergent.

  • Growers have eroded their ryegrass seedbanks by 99.8% from an average of 183 ryegrass/m2 in 2001 to 0.33 ryegrass/m2 in 2017 across the 27 focus paddocks.

  • In 2017, the department carried out over 320 trials across the state from Carnarvon in the north to Esperance in the south.

  • There are many factors to consider when deciding whether a crop is good enough to carry through to harvest, for example, feed value for livestock, potential weed seed set, level of herbicide resist

  • Following the extended dry conditions this autumn, weeds are now emerging and becoming a challenge for growers to manage in paddocks that may have patchy crops, crops with staggered emergence or no

  • Roly poly, also known as prickly saltwort or tumbleweed (Salsola australis), is a native species found throughout Australia.

  • Tar vine (Boerhavia coccinea) is found throughout Australia, with the exception of Tasmania.

  • Button grass (Dactyloctenium radulans) is a native species found throughout Australia.

  • The viability of annual ryegrass seed can be reduced substantially by desiccation, pre-harvest spraying or swathing of canola depending on the product and timing.


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