Herbicides are chemicals that destroy or inhibit the growth of plants.  They play a vital role in an Integrated Pest Management plan. Numerous herbicides are registered with the Australian Pesticides and Veterinary Medicines Authority for use in Western Australia (WA).

In 2006–07, 91.4% of Western Australian agricultural businesses used herbicides to control weeds. Total expenditure for all types of weed control was $341 million (Australian Bureau of Statistics).

Weed control is a shared responsibility between landholders, grower groups, biosecurity groups and the Department of Agriculture and Food, Western Australia (DAFWA). To protect WA’s agriculture, DAFWA:

  • works with landholders, grower groups, community groups and biosecurity groups
  • provides information on using herbicides, herbicide resistance and herbicides that can be used on declared plants in WA.

If you need advice on herbicides please search our website or the Australian Pesticides and Veterinary Medicines Authority website. Our Pest and Disease Information Service (PaDIS) can also put you in contact with a herbicide expert.


  • Control information for skeleton weed (Chondrilla juncea L.), a declared pest in Western Australia.

  • Control methods for noogoora burr (Xanthium strumarium) a declared p

  • Herbicide performance can vary greatly depending on a number of factors. These can include compatibility of herbicides, water quality, sprayer decontamination and controlling stressed weeds.

  • 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.

  • Spray-topping is a very effective method for managing annual grass seed set in pastures.

  • 'Crop-topping' is the late application of herbicides to prevent weed seed-set.

  • Windmill grass (Chloris truncata) is a native species and is the tenth most common summer weed species in the Western Australian wheatbelt.

  • Annual ryegrass (Lolium rigidum) is one of the most serious and costly weeds of annual winter cropping systems in southern Australia.

  • Herbicides play a vital role in integrated weed management programs.

  • Hyssop loosestrife (Lythrum hyssopifolia) is a widely distributed weed in the south west of Western Australia.