Native to central America, Crofton weed (Ageratina adenophora) was introduced to Australia in 1875 as an ornamental plant but has since spread out of control. Newly-cleared land along the New South Wales and Queensland borders was overrun in the 1940s.
Crofton weed is most prevalent in South East Queensland, invading pastures and colonising roadsides and forest edges. It is an aggressive weed which is poisonous to horses, causing Tallebudgera Horse Disease.
Crofton weed in not a declared pest plant under Queensland legislation.