Black willow (Salix nigra)

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

Profile

Impact

Black willow is an invasive woody weed of rivers, streams and wetlands throughout temperate Australia. It is considered one of the most serious weeds of riparian and wetland ecosystems in Australia, where it spreads quickly and forms dense stands along water courses.

Black willows were originally planted during the 1960s for soil stabilisation projects along streams and river banks in Victoria and southern NSW. They are now considered to cause erosion and flooding, and reduce water availability and quality.

Distribution

Black willow is native to eastern Canada, and eastern and central USA, particularly along the Mississippi River. In its native range it can form large stands and has commercial importance. Black willow does not appear to be a problematic weed in any other part of the world.

In NSW, the largest infestations of black willow occur in the Hawkesbury-Nepean and Murrumbidgee catchments, which are subject to ongoing control and monitoring programs. Black willow has the potential to invade rivers, streams and wetland areas throughout NSW.

Distribution map

Spread

Black willow spreads mostly from seed but can also grow from broken stems. A female tree produces thousands of light fluffy seeds each year that can travel by wind or water. Seeds will only survive for a couple of weeks, yet under ideal conditions (bare wet ground in full sunlight) germination is fast and a mass of seedlings may be seen in about a month.

Stem fragments may break off and travel many kilometers downstream. New roots will grow in water from these fragments, resulting in new infestations.

Black willow is able to hybridise (cross-pollinate) and breed with other willow species.  This may increase problems caused by other Salix species.

Description

Black willow is an upright deciduous tree that stands up to 20 m high, usually with one trunk but able to have up to 4 main stems. Young trees have a conical shape which broadens with age. Male and female trees are equally common.

Key identification features

  • Bark is rough, dark brown-to-grey in colour, with deep fissures (splits or cracks in the bark) on older stems. Twigs are a shiny red-brown in the sun and brittle at the base, snapping easily from the main stem.
  • Leaves are bright green, slender, 4–10 cm long and 7–17 mm wide with toothed edges.
  • Flowers are long slender catkins, a stalk of many petal-less flowers, which are either male or female (on separate trees). Male catkins are 6–12 cm long with widely spaced fragrant yellow flowers. Female catkins are 4–6 cm long with green bulbous ovaries on short stalks. Catkins appear in spring with new leaves.
  • Capsules are 4.5–5.5 mm long and tiny seeds are covered in long silky hairs.

Habitat

Black willows prefer open sunny positions and will grow along the banks of streams, rivers, lagoons and swamps, spreading their roots out into the water. Once established they can spread further into a water course, taking up large amounts of water, and eventually diverting the natural flow.

Acknowledgements

Reviewed by: Michael Michelmore; Edited by: Elissa van Oosterhout

References

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.

Jacobs, SWL and Murray, L (2000). Salix nigra spp., in PlantNET - The Plant Information Network System of The Royal Botanic Gardens and Domain Trust, Sydney, Australia. Available at http://plantnet.rbgsyd.nsw.gov.au

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Control

A local council weeds officer will assist with identification, control information, removal and eradication. Very few herbicides are registered for use near water and extreme care must be taken to avoid contact with any non-target species.

Herbicide options

WARNING - ALWAYS READ THE LABEL
Users of agricultural or veterinary chemical products must always read the label and any permit, before using the product, and strictly comply with the directions on the label and the conditions of any permit. Users are not absolved from compliance with the directions on the label or the conditions of the permit by reason of any statement made or not made in this information. To view permits or product labels go to the Australian Pesticides and Veterinary Medicines Authority website www.apvma.gov.au

See Using herbicides for more information.


Glyphosate 360 g/L (Roundup®)
Rate: 1.0–1.3 L in 100 L of water
Comments: Spray to wet all foliage. Use the higher rate for trees 1–2 m high.
Withholding period: Nil.
Herbicide group: M, Inhibitors of EPSP synthase
Resistance risk: Moderate


Glyphosate 360 g/L (Roundup®)
Rate: Undiluted
Comments: Stem injection.
Withholding period: Nil.
Herbicide group: M, Inhibitors of EPSP synthase
Resistance risk: Moderate


Picloram 44.7 g/kg + Aminopyralid 4.47 g/L (Vigilant II ®)
Rate: Undiluted
Comments: Cut stump/stem injection application. Apply a 3–5 mm layer of gel for stems less than 20 mm. Apply 5 mm layer on stems above 20 mm .
Withholding period: Nil.
Herbicide group: I, Disruptors of plant cell growth (synthetic auxins)
Resistance risk: Moderate


Triclopyr 240 g/L + Picloram 120 g/L (Access™ )
Rate: 1.0 L per 15 L of diesel
Comments: Cut stump application method.
Withholding period: Nil
Herbicide group: I, Disruptors of plant cell growth (synthetic auxins)
Resistance risk: Moderate


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Legal requirements

The content provided here is for information purposes only and is taken from the Noxious Weeds Act 1993.

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 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
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 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
Bland 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
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 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
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 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
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 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
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 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
Coolamon 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Cootamundra-Gundagai 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant only in the area formerly known as Cootamundra Shire Council
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 only in the area formerly known as Gundagai Shire Council
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 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
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 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Griffith 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
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 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
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 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
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 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
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 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
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) 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Murrumbidgee 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Nambucca 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
Narrabri 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
Narrandera 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
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 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
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 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
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 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
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 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
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 2 Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant
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 2016