The Threat
The recent discovery of the first known naturalised population of seeding willows in Tasmania is cause for alarm. Wild pussy willows are the most invasive willow species in Australia, with large populations already occurring in Victoria. They seed prolifically and can colonise moist areas remote from streams tens of kilometres away.
Given Tasmania’s limited distribution of known seeding willow populations, we need to eradicate them now before it’s too late.
The Tasmanian Seeding Willows Project aims to control major infestations of wild pussy willow in Tasmania and develop a strategic ongoing management approach to achieving eradication within ten years.
The project, which runs from July 2006 to June 2009, is funded by the Australian Government’s Defeating the Weed Menace Programme and is being implemented by Tasmanian Land & Water Professionals Pty Ltd, with guidance from a steering committee.
For more information, contact Elizabeth Schrammeyer:
Phone: 03 6234 2939
Email: admin@tlwp.com.au
Webpage: www.tlwp.com.au
Newsflash!!
This project is now finished....
Please visit our willows final report page for information materials to download and more information.
A final report, including maps and recommendations and along with the database has been sent to relevant municipalities and NRM Regions as well as DPIW and DAFF, and the important bits are available here for download.
In Spring (august - september)
Check for female flowers!!! If you find any female plants please contact your council's Weeds/ NRM Officer or your Regional Weed Management Officer at DPIW.
Wild Pussy Willows
The seeding willow of concern in Tasmania is pussy willow (Salix cinerea). This shrub or small tree is without doubt the most invasive of willows currently in Australia. It seeds prolifically and can colonise moist areas remote from streams tens of kilometres away.
Form: Shrub or small multi-stemmed tree with a wide, rounded crown (much wider than high in mature trees) and several sturdy branches arising near ground level.
Leaves: Broad, variable, hairy both sides, with toothed or wavy edges. Leaves are deciduous, with new leaves emerging in late September.
Stems: Smooth grey bark with longitudinal ridges along the stem. Twigs and branches are hard to break (as opposed to crack willow).
Flowering: Occurs briefly in late August to early September. Male flowers ovate in shape and white with yellow tips; female flowers green and cylindric-ovate in shape. During flowering, the females are a distinct colour and can be spotted from afar!
Reproduction: Predominantly by seed that ripens 3-4 weeks following flowering. The seed is small with long silky hairs attached to one end to aid in dispersal. Seed crops may be massive and dispersal is by wind or water, over tens or sometimes hundreds of kilometres. Can also produce viable seed by hybridising with other willows species.
Seed viability is extremely brief (about two weeks) and seeds need to lodge on suitable bare and wet soils or other substrates. Germination is extremely rapid, occurring within 24 hours. Seedling growth may be rapid where conditions are favourable.
Distribution
Occurs: In Victoria and New Zealand it is highly invasive in swamps, drainage lines and other moist sites and is a major wetland and riparian weed species. In Tasmania, isolated infestations occur south of Hobart in the Kingborough and Huon municipalities; near Queenstown on the West Coast; and on the North West Coast near Ulverstone/Penguin and Lileah/Nabageena.
Conditions for invasion: Has proven to be extremely adaptable, invading just about any boggy and intermittently moist sites, anywhere from sea level to above the alpine tree line. Sites most likely to be invaded are areas where bare, wet ground exists for a month following seed shed (around late October / early November).
Legal Status
Salix species (except S. babylonica, S. x calodendron and S. x reichardtii) are listed as Weeds of National Significance and declared under Tasmania’s Weed Management Act 1999.
Warning!: S. babylonica, S. x calodendron and S. x reichardtii, although not declared can still spread by branches, and can hybridise with other willows to produce viable seed.
Control options
The following control options are recommended for Tasmanian conditions.
Physical: Hand-pull young seedlings while they are still small (<0.5m tall). Any small roots left in the ground will not lead to suckering or regrowth.
Chemical: Cut-stump: suitable for smaller specimens that can be safely removed. Cut stems off at ground level or below the lowest branch and immediately paint on a herbicide registered for use (e.g. Roundup Biactive). Remove cut stems and pile away from stream and burn, or paint each removed stem with herbicide to ensure they don’t take root.
Stem Injection: suitable for larger shrubs or trees. Make cuts or drill holes 20-30mm into the sapwood around the stem and below the lowest branches. Ensure a maximum distance of 100mm between cuts/holes and that they angle downward to avoid herbicide spillage. Immediately inject herbicide into cut/holes at the recommended rate. Leave the tree undisturbed for at lest 12 months to ensure a successful kill. The optimal time to stem inject trees is summer to early autumn.
Follow-up: Re-growth from stumps, pieces of stems or seeds will need to be followed up with monitoring and further control for 3–5 years after the initial effort.
Acknowledgements
Weeds of National Significance: Weed Management Guide – Willows (2003); CRC for Australian Weed Management.
Weeds of National Significance: Willow (Salix taxa, excluding S. babylonica, S. x calodendron and S. x reichardtii) Strategic Plan (2000); National Weeds Strategy Executive Committee.
Weeds of National Significance: Willow Strip Newsletter Issue 1(2006); National Willows Taskforce.
