Grey sallow (Salix cinerea)

WEED ALERT: REGIONALLY PROHIBITED WEED
If you see this plant contact your council weeds officer, the NSW Invasive Plants & Animals Enquiry Line 1800 680 244 or email weeds@dpi.nsw.gov.au
Also known as: Wild pussy willow

Profile

Impact

Grey sallow is the only willow species known to invade non-riparian habitats. Provided there is sufficient soil moisture available, grey sallow can rapidly form dense stands in a variety of environments. It has invaded riverine and wetland habitat through to pristine alpine regions. Grey sallow can remain relatively stable in size for a long period of time, and then experience a population explosion under the right conditions.

Grey sallow affects riverine health and stream bank stability. It does this by; crowding out native species, spreading its large root network into the water, taking up large amounts of water and eventually diverting the natural flow of water.  The annual autumn leaf-drop can also affect water quality by suddenly increasing organic matter and nutrient levels.

Distribution

Native to Eurasia and northern Africa. Grey sallow has become a weed in New Zealand and the USA. Originally planted, along with other willow species, for erosion control, stream bank stabilisation and windbreaks.

Infestations of grey sallow occur throughout many river systems of Tasmania, eastern and central Victoria and the Tableland regions of New South Wales. Small localised infestations occur near Perth and Adelaide.  

Spread

Grey sallow reproduces by seed and vegetatively from detached branches and twigs that take root. Most spread is by seed. A female tree produces thousands of light fluffy seeds each year that can travel by wind and water. Unless conditions are right (wet, bare ground in full sunlight), seeds will not germinate. When conditions are right, mass germination events can take place resulting in thousands of seedlings in one season.

Stem fragments and twigs break off and travel many kilometers downstream. Broken twigs develop new roots, resulting in new infestations.

Grey sallow is able to cross-pollinate with other willow species, forming hybrids. Currently two subspecies of grey sallow are known to exist—Salix cinerea subsp. cinerea and Salix cinerea subsp. oleifera.

Lifecycyle

Flowering occurs in spring, with flowers only lasting 2–3 weeks. If conditions are right, germination of dispersed seed begins in late spring and extends throughout the summer. New season leaf growth occurs after flowering.

Description

Grey sallow is a deciduous tree or more commonly a large spreading shrub. The canopy of grey sallow has a characteristic dome shape. As a shrub it commonly grows 1–2 m high and wider than it is tall. As a tree it can grow to 12 m high.

Stems

  • many upright stems extend from the base
  • tips may slightly droop when mature
  • flexible at the base and hard to break
  • young twigs and branches are dark reddish-brown in colour
  • hairy when young, becoming hairless with age
  • long visible ridges present when the bark is removed

Bark

  • dark grey to dark grey-brown in colour
  • smooth when young becoming fissured with age

Leaves

  • 2–7 cm long and 1.5–3.5cm wide
  • generally oval with a short, pointed tip
  • dark green above, blue-green below
  • initially hairy on both sides, remaining hairy underneath
  • emerge after flowering

Flowers

  • long slender, cylindrical catkins—a stalk of many petal-less flowers
  • catkins are either male or female
  • male catkins—golden yellow, 1.2–3 cm long and 1.3–1.8 cm wide
  • female catkins¬—green, 1.2–3 cm long initially then elongating up to 11 cm, 1.3–1.8 cm wide
  • an individual plant can have male catkins, female catkins or both

Fruit

  • a capsule
  • splits into two
  • 5.5–9 mm long

Seed

  • small with long silky hairs

Habitat

Preferring cool, temperate climates, grey sallow will grow at various altitudes, provided the location is sunny and seasonally waterlogged. This includes riverine habitats, wetlands, swamps, coastal dunes, wet forests and boggy alpine regions. It is frost tolerant and grows in all soil types that are either neutral or acidic. Grey sallow will invade disturbed and undisturbed areas.

References

CABI invasive species compendium online data sheet. Salix cinerea. CABI Publishing 2011. www.cabi.org/ISC. Accessed August 2014.

Holland Clift, S and Davies, J (2007) Willows National Management Guide: current management and control options for willows (Salix spp.) in Australia. Victorian Department of Primary Industries, Geelong.

Holland Clift, S (2008) National willows resource kit, resource sheet 2: willow identification, an essential skill for effective willow management, Victorian Department of Primary Industries, Geelong.

Hosking JR, Sainty GR, Jacobs SWL & Dellow JJ (in prep) The Australian WeedBOOK.

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Control

Whenever implementing control measures of grey sallow close to a water course, careful planning and management is essential to ensure there is minimal to no damage of the site.

Mechanical control

Small seedlings can be hand pulled from the ground. Mechanical control using large machinery on mature plants is not recommended. Broken branches and twigs can become pushed into the ground; allowing new plants to grow and a new infestation emerge.

Machinery is often used in combination with herbicide control. When using the cut stump method, fallen trees need to be moved away from the water course. Plants killed using a stem injection method may also need to be removed.

Herbicide control

Herbicides registered to control woody weeds are effective in controlling grey sallow. When plants are located in and around water courses, use only herbicides registered for use in aquatic areas.

Methods of application include foliar spray, cut stump and stem injection. These control measures can be used at any time of the year. Only use foliar application on plants under 2 m tall with clean foliage. Silt on the leaves can reduce how much herbicide the plant uptakes.      

Follow up control

All control efforts will require monitoring and follow up on any regrowth from stumps, broken stems and seed. To be effective, grey sallow control is a long term program.

Biological control

The willow sawfly is not known to feed on grey sallow. 

Herbicide options

Contact your local council weeds officer for control advice for Grey sallow (Salix cinerea).

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Legal requirements

The content provided here is for information purposes only and is taken from the Noxious Weeds (Weed Control) Order 2014 published in the NSW Government Gazette, detailing weeds declared noxious in New South Wales, Australia, under the Noxious Weeds Act 1993. The Order lists the weed names, the control class and the control requirements for each species declared in a Local Control Authority area.

Area Class Legal requirements
Albury 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Balranald 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Bayside 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Bega Valley 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Bellingen 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Bland 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Blue Mountains 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Bogan 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Bourke 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Brewarrina 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Broken Hill 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Burwood 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Cabonne 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Camden 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Campbelltown 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Canada Bay 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Canterbury-Bankstown 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Carrathool 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Castlereagh Macquarie County Council 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Central Coast 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread and the plant must not be sold, propagated or knowingly distributed
Central Darling 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Central Murray County Council 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Cessnock 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread and the plant must not be sold, propagated or knowingly distributed
Clarence Valley 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Cobar 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Coffs Harbour 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Coolamon 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Cootamundra-Gundagai 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Cowra 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Cumblerland 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Dungog 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread and the plant must not be sold, propagated or knowingly distributed
Eurobodalla 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Fairfield 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Federation 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Forbes 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Georges River 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Glen Innes Severn 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Goulburn Mulwaree 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Greater Hume 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Griffith 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Gunnedah 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Gwydir 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Hawkesbury River County Council 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Hay 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Hornsby 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Hunters Hill 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Illawarra District Weeds Authority 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Inner West 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Inverell 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Junee 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Kempsey 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Ku-ring-gai 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Lachlan 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Lake Macquarie 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread and the plant must not be sold, propagated or knowingly distributed
Lane Cove 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Leeton 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Liverpool 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Liverpool Plains 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Lockhart 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Lord Howe Island 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Maitland 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread and the plant must not be sold, propagated or knowingly distributed
Mid-Coast 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Mid-Western Regional 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Moree Plains 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Mosman 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Murray River (formerly Wakool) 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Murrumbidgee 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Nambucca 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Narrabri 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Narrandera 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Narromine 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
New England Tablelands County Council 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Newcastle 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread and the plant must not be sold, propagated or knowingly distributed
North Sydney 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Northern Beaches 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Orange 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Parkes 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Parramatta 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Port Macquarie-Hastings 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Port Stephens 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread and the plant must not be sold, propagated or knowingly distributed
Queanbeyan-Palerang Regional 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Randwick 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Rous County Council 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Ryde 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Shoalhaven 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Snowy Monaro Regional 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Snowy Valleys 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Southern Slopes County Council 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Strathfield 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Sutherland 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Sydney 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Tamworth Regional 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Temora 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Tenterfield 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Unincorporated Area of Western Division 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Upper Hunter County Council 4 Locally Controlled Weed
The growth of the plant must be managed in a manner that continuously inhibits the ability of the plant to spread and the plant must not be sold, propagated or knowingly distributed
Upper Lachlan 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Upper Macquarie County Council 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Wagga Wagga 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Waverley 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Weddin 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Wentworth 3 Regionally Controlled Weed
The plant must be fully and continuously suppressed and destroyed and the plant must not be sold, propagated or knowingly distributed
Western Plains Regional 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Willoughby 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Wingecarribee 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Wollondilly 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Woollahra 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant

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Reviewed 2014