Senegal tea plant (Gymnocoronis spilanthoides)

Profile

Impact

Senegal is a hardy plant with a rapid growth rate, growing on the banks of watercourses and in shallow water. 

Senegal tea can form dense erect stands, or extend mats of stems from the banks across the water surface. This impedes flow, ecosystem function, navigation, and recreational activities. Senegal tea is one of 28 weeds on the Australian Government’s National Environmental Alert List. These weeds are in the early stages of establishment and could seriously threaten biodiversity if not managed.

Distribution

Senegal tea is native to tropical and subtropical America (from Mexico to Argentina). It is an invasive aquatic weed in New Zealand, India and China. It was introduced to Australia from India for the aquarium trade in the 1970s, and was first recorded as naturalised in the Manning River near Taree in 1980. Infestations have also occurred at Dapto, Byron Bay and Gloucester and these have since been controlled. The current distribution in NSW is made up of isolated infestations on the Central Coast, the Hunter and Sydney regions including Royal National Park and the Hawkesbury River.

Distribution map

Spread

Senegal tea reproduces by plant fragments and by seed. Plant fragments develop roots and new stems when they come into contact with soil. Most new infestations in Australia occur as a result of plant fragments. While Senegal tea produces prolific amounts of seed, seed germination appears to be a minor form of spread in Australia. Light is required for seed germination and most seeds germinate in spring (some continue to germinate through summer). Seedlings develop quickly as temperatures increase. Seeds can germinate in shallow water, and most fall close to the parent plant. Seeds can be moved in faster flowing water or in mud on vehicles or animals. Plant fragments can be moved in flowing water or in flood waters. Plants are dormant during winter, reshooting from the crown and from protected buds at stem nodes the following spring.

Description

Senegal tea is a perennial plant that can grow in dense stands or as clumped bushes up to 1 m high.

Leaves and stems

Stems are ribbed, pale green and erect, becoming prostrate as they lengthen and age. They are hollow between the nodes and buoyant, able to form tangled floating mats. Stems branch at nodes and are 1 – 1.5 m long and 5 – 10 mm in diameter, increasing to 1 – 2 cm with age. Fine, fibrous roots form at stem nodes.

The tapered leaves are dark green, 5 –  20 cm long, 2.5 – 5 cm wide, grow on short stalks and have serrated, slightly wavy margins. They occur in opposite pairs along the stems.

Flowers and seeds

White, pom-pom-like flowers 1.5 – 2 cm in diameter occur in groups at the ends of stems. Flowering starts in late spring or early summer and continues until temperatures fall. Flowers have a strong fragrance. Seeds are yellow-brown, 5 mm in diameter, and ribbed.

Habitat

Senegal tea prefers tropical, subtropical and warm temperate regions, and will grow in damp floodplain soils, on the margins of creeks and dams, in wetlands and in still or slow-flowing fresh water. Plants can grow when fully submerged, but growth is slower and plants are smaller. In some infestations plants have been found growing on the floodplain up to 150 m from the water body.

References

van Oosterhout E (2010). Senegal tea Primefact 993. NSW DPI, Orange. 

Technical reviewers: Rod Ensbey, Melissa Freeman, Birgitte Verbeek.
Information provided by: Kim Hignall and Paul Mason

References

  • CRC for Australian Weed Management (2003), Senegal tea plant – Gymnocoronis spilanthoidesWeed Management Guide.
  • Hosking J. R, Sainty, G. R., Jacobs, S. and Dellow, J.J., Unpublished Manuscript, "The Australian WEEDbook", Industry & Investment NSW, Orange.
  • Sainty G. R. and Jacobs S. W. L. (2003) Waterplants in Australia, 4th Ed, Sainty & Associates Pty Ltd, Potts Point.

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Control

Control should not be attempted by individuals as Senegal tea can spread very easily from plant fragments. If you suspect you have Senegal tea seek advice from your local Council Weeds Officer. Senegal tea is a Class 1 notifiable weed in NSW that must be reported to the Council or Local Control Authority. This plant can be eradicated if detected early in its establishment.

Physical removal

Mechanical and manual removal can be carried out in small accessible infestations. Issues associated with disposal of the removed plant material and soil and the risk of spreading stem fragments are major concerns. Again it is recommended that control not be attempted by individuals. Qualified personnel should treat infestations with herbicide prior to removing plant material to reduce the risk of spreading viable stem fragments. Removed plant material should be dried and incinerated wherever possible as any plant material and soil that remains damp has the ability to spread viable plant fragments and seeds.

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.


PERMIT 14729 Expires 30/06/2019
Glyphosate 360 g/L (Only products registered for aquatic use)
Rate: 1 L per 100 L of water
Comments: Refer to permit for critical use comments
Withholding period: Nil.
Herbicide group: M, Inhibitors of EPSP synthase
Resistance risk: Moderate


PERMIT 14729 Expires 30/06/2019
Metsulfuron-methyl 600 g/kg (Brush-off®)
Rate: 5–10 g per 100 L of water
Comments: Spot spray application. Do not spray directly onto water or non-target species.
Withholding period: Nil (recommended not to graze for 7 days before treatment and for 7 days after treatment to allow adequate chemical uptake in target weeds).
Herbicide group: B, Inhibitors of acetolactate synthase (ALS inhibitors)
Resistance risk: High


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Biosecurity duty

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 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.
Greater Sydney
Exclusion zone: whole region except the core infestation area of the Central Coast Council, Royal National Park and the Hawkesbury-Nepean River and its tributaries.
Regional Recommended Measure*
Whole region: Land managers mitigate the risk of the plant being introduced to their land. The plant or parts of the plant are not traded, carried, grown or released into the environment. The Local Control Authority should be notified if the plant is found. Exclusion zone: The plant is eradicated and the land kept free of the plant. Core infestation area: Land managers prevent spread from their land where feasible.
Hunter Regional Recommended Measure*
Land managers should mitigate the risk of new weeds being introduced to their land. The plant should be eradicated from the land and the land kept free of the plant. The plant should not be bought, sold, grown, carried or released into the environment. Notify local control authority if found.
Murray Regional Recommended Measure*
Land managers should mitigate the risk of new weeds being introduced to their land. The plant should be eradicated from the land and the land kept free of the plant. The plant should not be bought, sold, grown, carried or released into the environment. Notify local control authority if found.
North Coast Regional Recommended Measure*
Land managers should mitigate the risk of new weeds being introduced to their land. The plant should be eradicated from the land and the land kept free of the plant. Notify local control authority if found.
North West Regional Recommended Measure*
Land managers should mitigate the risk of new weeds being introduced to their land. The plant should be eradicated from the land and the land kept free of the plant. The plant should not be bought, sold, grown, carried or released into the environment. Notify local control authority if found.
Riverina Regional Recommended Measure*
Land managers should mitigate the risk of new weeds being introduced to their land. The plant should be eradicated from the land and the land kept free of the plant. The plant should not be bought, sold, grown, carried or released into the environment. Notify local control authority if found.
South East Regional Recommended Measure*
Land managers should mitigate the risk of new weeds being introduced to their land. The plant should be eradicated from the land and the land kept free of the plant. The plant should not be bought, sold, grown, carried or released into the environment. Notify local control authority if found.
*To see the Regional Strategic Weeds Management Plans containing demonstrated outcomes that fulfill the general biosecurity duty for this weed click here

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Reviewed 2017