Siam weed in Queensland, Australia transitions to management

Publication Date

Mon, 11 Nov 2013, 00:00

Last Updated

June 23, 2023, 5:37 a.m.

Report Number

AUS-30/5

Country

Australia

Pest Id

Eupatorium odoratum - (EUPOD)

Report Status

Final

Hosts

Species will establish in a variety of habitats including riparian zones, beach foreshores, along waterways, dry hill slopes, open grasslands and pastures, melaleuca swamps, rainforest and dry eucalypt forest.

Pest Status (old values from ISPM 8 -1998 )

Present: but managed

Pest Status (ISPM 8 - 2021)

Present: not widely distributed and under official control

Geographical Distribution

Known area (as at 2013) of infestation is 159 hectares in various locations spread over more than 400km from Mossman to Townsvlle, Queensland. See attached map.

Summary

Siam weed probably entered Australia as a pasture contaminant. It was under eradication from 1994, but in 2012, the decision was made that it was not technically feasible to eradicate due to difficulties in being able to confidently and accurately delimit the weed across catchment areas in north Queensland. Arrangements have been developed to manage the weed with a management strategy put in place to limit the spread and impact of infestations on agricultural production, cultural assets and the environment. The implementation of the national strategy began in August 2013.

Siam weed is an invasive, weedy perennial shrub that can grow to 2-3 m in height or reach 10-20 m when supported by other vegetation. It grows vigorously throughout the wet season and may grow up to 5 m a year. In northern Australia, it has 2 flowering periods a year. Seed production is prolific and germination to flowering can take as little as 6 months. Siam weed probably entered Australia as a pasture contaminant. It has been under eradication since 1994. Control measures include herbicides, manual control in environmentally sensitive areas and controlled burning of infestations. Aerial surveillance has been used in conjunction with ground surveillance to detect infestations.

Danger