Parthenium hysterophorus L.
Parthenium weed is a State prohibited weed
State prohibited weeds are the highest category of declared noxious weeds in Victoria. By definition, they are either not yet in Victoria, or are here in small numbers, where their eradication is still possible.
All sightings should be reported to Agriculture Victoria immediately by calling 136 186 or emailing firstname.lastname@example.org.
Why is it important to report parthenium weed sightings to Agriculture Victoria
Parthenium weed costs the agricultural industry in Queensland over $22 million annually in lost production and control costs, and is a serious threat to Victoria's agriculture.
Each plant can germinate, grow and set seed within four weeks, resulting in multiple germinations in one year. One plant can produce up to 20,000 seeds per year. It produces chemicals which inhibit the growth of other plants.
Contact with, and pollen from, parthenium weed can cause severe allergic reactions such as dermatitis and hay fever in sensitive individuals It is toxic to cattle.
Parthenium weed originates from parts of North and South America. It was first discovered in Queensland in 1955 and was thought to be introduced via contaminated machinery during World War II. It currently infests over eight million hectares of Queensland and is also present in New South Wales and the Northern Territory. It has not been found in Victoria but there is a high risk that it could be introduced.
Parthenium weed can germinate, grow and set seed within a four week period.
How to identify parthenium weed
Parthenium weed is an annual or short-lived herb to 2 m tall. It invades disturbed land such as roadsides, stockyards and overgrazed pastures. It has the potential to infest the semi-arid regions of northern Victoria.
Leaves are grey-green, deeply divided, 5–20 cm in length and covered in fine hairs. The leaves are initially in a flat rosette. Mature stems have distinct grooves along them and are covered in fine hairs.
Flowers are creamy-white, star-shaped and 4 mm across. They are in open branched clusters above the foliage. Flowering can occur all year round in favourable conditions, but usually in summer.
What should you do if you find parthenium weed?
If you think you have seen a parthenium weed plant, please contact Agriculture Victoria on 136 186 or send an email to email@example.com.
Please do not attempt to treat or dispose of this weed yourself. Agriculture Victoria will treat, remove, and dispose of parthenium weed safely, at no cost to the land owner