Parthenium weed on the march towards Victoria

Parthenium weed.

The State prohibited weed, parthenium (Parthenium hysterophorus), is spreading south towards Victoria.

Parthenium weed has not been recorded in Victoria, but it is widespread and problematic in Queensland and is spreading south through New South Wales. It has the potential to cause significant damage to Victorian agriculture should it establish here.

Preferring semi-arid growing conditions, Agriculture Victoria is asking Mallee residents in particular to be on the lookout for this devastating weed.

“Interstate, parthenium weed has been found to spread in fodder, grain, organic chicken feed, and on vehicles and machinery, especially from Queensland,” Agriculture Victoria Biosecurity Manager Angela Constantine said.

“Therefore we are asking those who have imported these items to be vigilant in keeping a look out for parthenium weed on their properties.”

Parthenium weed produces chemicals which inhibit the growth of nearby plants, can cause dermatitis and hayfever in people and is toxic to cattle.

It can germinate, grow and set seed within a four-week period, with one plant producing up to 20,000 seed heads per year.

“It is for these reasons that parthenium weed is declared a State prohibited weed in Victoria, the highest category of noxious weed and a weed that Agriculture Victoria wants to keep out of Victoria or eradicate if it arrives,” Ms Constantine said.

Agriculture Victoria will control all parthenium weed infestations found in Victoria at no cost to the landholder.

Parthenium weed has deeply divided grey-green leaves, that are 5 – 20 centimetres long and are initially in a flat rosette. Mature stems have distinct grooves.

The flowers are creamy-white, star shaped and only four millimetres wide. Flowering can occur all year around in suitable conditions, but it mainly flowers in summer.

If you suspect you have parthenium weed on your property, please take a photo of the suspect plant and email it to, or call the Customer Contact Centre on 136 186.