Mexican poppy weeds in Western Australia

Appearance

Mexican poppy's native range extends northwards to Texas and southwards to Central America. It is widely established as a weed in the tropics and warm temperate regions in the world. 

Argemone mexicana is a declared pest in Western Australia (WA). Although it is not established in WA, this weed has occasionally being found in Perth. A. mexicana  is subject to eradication if found. 

Argemone ochroleuca is a widespread weed in WA and is not a declared pest. It is widely distributed in the pastoral areas, mainly along river systems, moist flats and sand dunes. A. ochroleuca  is also present in some agricultural areas, but does not compete well with crops or in managed pastures.

Mexican poppy plants resemble thistles because of their toothed and prickly leaf margins.

Which Mexican poppy is this?

	Argemone mexicana REPORT THIS WEED This is a declared plant in WA	Argemone ochroleuca
form	herbaceous - annual
height	Up to 1.5m	Up to 1m
stems	Cylindrical, with scattered prickles
leaves	The plants are bristly stemmed with lobed spiny leaves Up to 15cm long, bluish-green               Up to 20cm long
flowers	2.4 to 4.5cm across. A. mexicana  has four to six golden yellow petals	About 6cm across. A. ochroleuca has four pale yellow or cream petals
seeds	Prickly oblong seed capsule containing up to 400 oval-shaped seeds

Agricultural and economic impacts

Any Mexican poppy is poisonous to stock. Although unpalatable some stock have died after eating contaminated hay or chaff, and poultry after eating seeds.

Mexican poppy seeds can contaminate grain during harvesting making it unsuitable for milling or stock feed. Seeds can be easily removed from grain by seed cleaning.

The seeds of Mexican poppy can stay dormant for many years, making control difficult.

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Control method

Control methods for Mexican poppy can be found in Mexican poppy control webpage

Only registered products can be used for weed and pest control. When using any agricultural chemicals please ensure that you always follow instructions on the label and any permit. Users of agricultural chemical products must always strictly comply with the directions on the label and the conditions of any permit.

Further information

Further information on Mexican poppy can be found on the Mexican poppy: what you should know page.