Restricted matter category Chromolaena odorata (Siam weed) · 2017. 10. 3. · Siam weed produces...
Transcript of Restricted matter category Chromolaena odorata (Siam weed) · 2017. 10. 3. · Siam weed produces...
Description: A scrambling woody shrub to 3 metres (higher as a scrambling climber) with distinctive
forked leaf venation and purple flush on new leaves. Clusters of white flowers in May-June and
October are a key identification feature. Distinguished from other weeds Bluetop, Praxelis and Billy
goat weed which all have mauve to purple flowers and are much smaller than Siam weeds’ 1-3 metres
in height.
Distribution: Widespread but localised in the Upper Herbert from Ravenshoe to Blencoe Creek, now
localised and abundant in the middle Herbert River above Abergowrie.
Impacts: This species can form dense thickets and outcompete native species and pasture in both
disturbed and undisturbed sites. Prefers richer soils in alluvial and riparian zones but will grow in rock
and escarpment.
Key projects: Subject of an National Eradication Program up until 2012 now in a transition to
management.
Delimitation
Detailed survey and surveillance is required to ensure Siam weed has not
established outside of the Herbert River Gorge and river channel. Landholders
downstream of Abergowrie to the mouth of the Herbert River should be on the
lookout for Siam weed during peak flowering times during May-June
Prevention
Siam weed produces wind-borne seed which can be easily spread by
machinery, vehicles and stock. Avoiding infested areas is essential for
preventing spread. Stock and agricultural machinery movements from
adjoining core infestation areas in the Upper Herbert, Tully/Murray, Johnstone
or Townsville areas should be managed to ensure they do no increase the
risk.
Asset protection
Siam weed currently occurs in difficult to access gorge and riverine country of
the Herbert River with the densest infestations upstream of Abergowrie.
Integrated control through a combined use of manual removal of single
plants, herbicide control of denser infestations and follow up after fire with
the control of seedlings will reduce the impacts of Siam weed.
Chromolaena odorata (Siam weed) P
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Biology x
Peak t
First/last flush p
Occasional y
n/a
Control x
Optimal t
Good p
Marginal y
Not recommended
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flower t x x t p t x t seed p t x x x x x t spray t x x x x x t t t t p p
mechanical y y y y y y y y y y y y cut x x x x x x t t t t t t
burn p t x x x t t
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l Chromolaena odorata (Siam weed)
Control
Spread
What is my biosecurity obligation?
Delimitation Ensure any machinery or vehicles moving from the infested areas are
free from plant material and soil. Spot spray isolated plants and
control isolated infestations. Control plants before seeding and prior
to slashing or disturbance.
Report any suspected plants or infestations to Hinchinbrook Shire
on 07 4776 4607.
Prevention zone
Asset protection
Ensure best practice weed hygiene measures are in place to reduce
risk of spread to new locations. Maintain weed free areas. Identify
high value assets and protect them from impacts where possible.
For more information on management aims in each zone refer to Using the Biosecurity Plan templates
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