Grey sallow is a deciduous, spreading shrub or tree. It is a type of willow that invades the banks of waterways reducing water quality and causing flooding, bank instability and erosion.
This weed belongs to the group Willows
This plant is a Weed of National Significance
This plant must not be sold anywhere in NSW
Grey sallows form dense stands along the banks of waterways and their roots spread into the bed of waterways. They:
Grey sallow is a type of willow which can be a deciduous shrub or tree. The shrub form is 1–2 m tall and is wider than it is high. The canopy has a characteristic dome shape. The tree form is up to 12 m tall.
Male and female flowers are usually on separate plants but occasionally both are on the same plant. All flowers are present in spring.
Male flowers are:
Female flowers are:
Grey sallow looks similar to Black willow (Salix nigra), which is a taller tree up to 20 m and has a single trunk or up to 4 stems from the base. The leaves are longer, thinner, have toothed edges and are hairless.
Grey sallow grows in the tableland regions of NSW and the Greater Sydney region.
It is native to Eurasia and northern Africa. Grey sallow has become a weed in New Zealand and the USA. It was originally planted, along with other willow species, for erosion control, stream bank stabilisation and windbreaks.
Grey sallow prefers cool temperate climates. It can invade both disturbed and undisturbed areas. It will grow at various altitudes as long as the location is sunny and is seasonally waterlogged. It tolerates frost and a wide range of soils including neutral and acidic soils.
It is the only willow species that grows outside waterways. With enough soil moisture, it can form dense stands in a variety of environments including:
Most spread is via seeds. Plants produce thousands of seeds each year but seeds are only viable for 8 weeks at the most.
Grey sallow infestations, with relatively few plants causing little impact, can remain stable in size for a long period of time. However, when ideal conditions occur, with bare moist ground and sunlight, masses of seedlings can quickly germinate. This causes a rapid and large increase in the number of grey sallow plants.
Grey sallow can cross-pollinate with other willow species forming hybrids. Hybrids can potentially be more invasive than the parent trees.
Wind and water spread the light, fluffy seeds. Seeds can spread up to 100 km via water.
Grey sallow can grow from small pieces of plants. Branches and twigs break off and travel many kilometres downstream. When they stop moving, they develop roots resulting in new infestations.
CABI invasive species compendium online data sheet. Salix cinerea. CABI Publishing 2011. www.cabi.org/ISC. Accessed August 2014.
Holland C. S. (2008) National willows resource kit, resource sheet 2: willow identification, an essential skill for effective willow management, Victorian Department of Primary Industries, Geelong.
Holland, C. S & Davies, J. (2007). Willows National Management Guide: current management and control options for willows (Salix spp.) in Australia. Victorian Department of Primary Industries, Geelong.
Hopley, T. & Young, A. G. (2015). Knowledge of the reproductive ecology of the invasive Salix cinerea, in its invaded range, assists in more targeted management strategies. Australian Journal of Botany, 63(6), 477-483.
Muyt, A. (2001). Bush invaders of South-East Australia: a guide to the identification and control of environmental weeds found in South-East Australia. RG and FJ Richardson.
PlantNET (The NSW Plant Information Network System). Royal Botanic Gardens and Domain Trust, Sydney. Retrieved 28 June 2021 from: https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Salix~nigra
Weed CRC. (2003). Weeds of National Significance Weed Management Guide: Willow (Salix spp.) Weed CRC.
Successful weed control requires follow up after the initial efforts. This means looking for and killing regrowth or new seedlings. Using a combination of control methods is usually more successful.
Clearing any vegetation along waterways may cause erosion and may require consent before any work starts. It is the landholder’s responsibility to obtain any approvals that may be required prior to undertaking clearing. NSW Local Land Services staff can assist you in understanding what other approvals may be required for your proposed activities under the Land Management Framework. Contact NSW Local Land Services for advice on the required approvals for your site.
To manage grey sallow:
Dig out or hand pull small seedlings up to 0.5 m tall. Small roots left in the ground do not usually regrow.
Only use excavators or bulldozers to remove larger trees and root systems in dry areas. In wet areas machinery pushes broken branches into the ground which produces many new plants.
Trees killed by stem injection should be left for 12 months before they are cut and removed. Plants should not be chipped unless they have been treated with herbicide. Removed plant parts should be stored away from flood prone areas. Small plant parts such as twigs can be bagged and disposed of at some waste centres. Contact your local council for advice on how to dispose of willows.
Only spray willows less than 2 m tall. Do not spray in autumn if the leaves have started to fall. Spray in areas where herbicides will not affect native plants or water bodies. Cover all of the foliage with herbicide. Only spray plants with clean foliage. Silt on the leaves can reduce herbicide uptake.
When: Year round but best results are in summer and early autumn.
Follow up: Wait at least 12 months after treatment.
Stem injection is suited to large trees. Make cuts or drill holes low all around the trunk to penetrate the spawood below the bark. Inject herbicide within 15 seconds into each cut or hole.
Leave the tree undisturbed for at least 12 months after treatment. After 12 months the trunks can be cut and stacked away from water flows. The tree may regrow if the timber is cut too soon.
When: Year round.
Follow up: Check and control regrowth or new seedlings in spring-summer.
Cut the trunk off below the first branches and immediately apply herbicide to both the trunk and the cut stump. Only use this method when all the cut material can be safely disposed of.
See Using herbicides for more information.
Glyphosate 360 g/L
(Various products)
Rate: 1.0 to 1.3 L in 100 L of water
Comments: Use higher rate for trees 1 to 2 m tall
Withholding period: Nil.
Herbicide group: 9 (previously group M), Inhibition of 5-enolpyruvyl shikimate-3 phosphate synthase (EPSP inhibition)
Resistance risk: Moderate
Glyphosate 360 g/L
(Various products)
Rate: Undiluted.
Comments: Stem injection. For trees with a basal diameter of 0 - 25 cm use 1 mL/cut. For trees with a basal diameter of 25 - 60 cm use 2 mL /cut.
Withholding period: Nil.
Herbicide group: 9 (previously group M), Inhibition of 5-enolpyruvyl shikimate-3 phosphate synthase (EPSP inhibition)
Resistance risk: Moderate
Picloram 44.7 g/L + Aminopyralid 4.47 g/L
(Vigilant II ®)
Rate: Undiluted
Comments: Cut stump application: Apply a 3–5 mm layer of gel for stems less than 20 mm. Apply 5 mm layer on stems above 20 mm. Stem inject application for trees: Make a series of cuts 15-20 mm deep around the trunk using an axe or saw. Space cuts evenly with no more than a 20-40 mm gap between them. Apply a 5 mm layer of gel over the lower surface of the cut.
Withholding period: Nil.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate
Triclopyr 240 g/L + Picloram 120 g/L
(Access™ )
Rate: 1 L in 15 L of diesel
Comments: Cut stump application for stems greater than 10 cm. Need to treat all stems
Withholding period: Nil
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate
The content provided here is for information purposes only and is taken from the Biosecurity Act 2015 and its subordinate legislation, and the Regional Strategic Weed Management Plans (published by each Local Land Services region in NSW). It describes the state and regional priorities for weeds in New South Wales, Australia.
Area | Duty |
---|---|
All of NSW | General Biosecurity Duty All pest plants are regulated with a general biosecurity duty to prevent, eliminate or minimise any biosecurity risk they may pose. Any person who deals with any plant, who knows (or ought to know) of any biosecurity risk, has a duty to ensure the risk is prevented, eliminated or minimised, so far as is reasonably practicable. |
All of NSW |
Prohibition on certain dealings
Must not be imported into the state, sold, bartered, exchanged or offered for sale. |
Greater Sydney |
Regional Recommended Measure* (for Regional Priority - Eradication)
Land managers should mitigate the risk of the plant being introduced to their land. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Notify local control authority if found. |
Murray |
Regional Recommended Measure* (for Regional Priority - Eradication)
Land managers should mitigate the risk of the plant being introduced to their land. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Notify local control authority if found. |
North Coast |
Regional Recommended Measure* (for Regional Priority - Eradication)
Land managers should mitigate the risk of the plant being introduced to their land. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Notify local control authority if found. |
Riverina
Core infestation areas: Snowy Valleys Council, Cootamundra - Gundagai Regional Council, Wagga Wagga City Council. Exclusion zone: All of Riverina except identified core infestation areas. |
Regional Recommended Measure* (for Regional Priority - Containment)
Within exclusion zone: Land managers should mitigate the risk of the plant being introduced to their land. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Notify local control authority if found. Within core infestation area: Land managers should mitigate the risk of the plant being introduced to their land. Land managers should mitigate spread of the plant from their land. A person should not buy, sell, move, carry or release the plant into the environment. Land managers should reduce the impact of the plant on assets of high economic, environmental and/or social value. |
*To see the Regional Strategic Weeds Management Plans containing demonstrated outcomes that fulfil the general biosecurity duty for this weed click here |
Reviewed 2023