Management Information
Mechanical: Gymnocoronis spilanthoides is very hard to kill and herbicides effective on similar plants kill only the upper parts of the plant. Any material that is below the water line is not killed, and can regrow. Hand pulling often results in regeneration and further spread. Mechanical removal has been used in conjunction with de-silting operations. First, herbicide was applied, then, 7 to 10 days later, all silt and plant material to a 1 metre depth was removed by machinery, taken away and spread out and dried. Weed material should always be dried out and treated like this, and, if possible, burnt. Alternatively it could be placed in a sealed plastic bag, left in the sunlight to rot and decompose and then disposed of at an approved land fill tip (Land Protection 2004).Cultural: As with all weed management, prevention is better and more cost effective than control. In Australia it is illegal to cultivate G. spilanthoides in most states and territories as it is a declared noxious weed. However, Senegal tea has been cultivated as both an aquarium plant and as a garden/ornanmental pond plant that attracts butterfly species. Vendor , state or territory weed control contacts should be contacted if G. spilanthoides is found to be for sale. Early detection and eradication are also important to prevent the spread G. spilanthoides. Small infestations can be eradicated if they are detected early but an ongoing commitment is needed to ensure new infestations do not establish (The Department of the Environment and Heritage, 2003). One should avoid buying seeds on the internet or from mail order catalogues to ensure they are free of weeds like G. spilanthoides (The Department of the Environment and Heritage, 2003). A statement of uses should also be included in here. In Australia, Senegal tea has been cultivated as both an aquarium plant and as a garden/ornamental pond plant that attracts butterfly species. Senegal tea is a resilient ornamental plant, it is also eaten by stock and has been noted as providing winter grazing in wet areas. Chemical: Long-term experience with glyphosate has shown it is not an effective eradication tool in south east Queensland. Some of the problems arise from the problem that it is non-selective and also kills native species such as swamp grasses and sedges. It also has no residual effect which means it creates a gap which is flooded by light, an ideal seedbed for senegal tea to re-grown. In addition, the plant fragments after toxin application, resulting in leaf abscission and propagule formation.
Location Specific Management InformationAustralia
The importation of G. spilanthoides into Australia is not permitted because of the risk of further spread, and the potential introduction of new genetic diversity that could make future control more difficult (The Department of the Environment and Heritage, 2003).
Unfortunately, as with many aquatic weeds, there is evidence that G. spilanthoides has been deliberately planted and farmed on public lands. These activities must be stopped to prevent its introduction and further spread throughout Australia (The Department of the Environment and Heritage, 2003).
“Members of the public are asked to be on the lookout for infestations” (Land Protection, 2004). Nelson (New Zealand)
G. spilanthoides has been designated as a 'Total control pest' by the the Tasman-Nelson Regional Pest Management Strategy. The strategy has its effect over the combined area that lies within the administrative boundaries of the Tasman District Council and Nelson City Council. The objective of the strategy is to eradicate known infestations of G. spilanthoides in the Tasman-Nelson region by 2006. Please see Hierarchy of Plant Designations for an explanation of designation terminology. Northland Region (New Zealand)
Senegal tea is considered to be a "surveillance pest plant" by the Northland Regional Council which shall assume responsibility for implementing appropriate management programmes with the aim of eradicating these pest plants if found in Northland. Surveillance pest plants have been identified as being of potential high risk to the Northland Region. The Regional Council will also seek to prevent their establishment or spread by prohibiting their sale, propagation and distribution. This will be achieved by Authorised Persons regularly monitoring plant retail and wholesale outlets for these pest plants. The Northland Regional Council will also disseminate technical information on control methods and the ecology of these plants, and fund research into biological control options. Research into their distribution and environmental impacts may also be carried out during the life of the Strategy. There is, however, no legal requirement for
landowners/occupiers to control established infestations.
It is also considered to be a "service delivery plant" by the Northland Regional Council. Plants will be treated by a recognised method, at intervals that will ensure the infestations are controlled, reduced and eventually eradicated. Further to this requirement, service delivery pest plants are banned from sale, propagation and distribution.
Please see the Pest management for defintions of pest designation. Queensland (Australia)
G. spilanthoides is a declared Class 1 plant under Queensland legislation. Declaration requires landholders to control declared pests on the land and waters under their control. A Local Government may serve a notice upon a landholder requiring control of declared pests (Land Protection, 2004).
The National Registration Authority has approved the minor off label use of Roundup BiactiveR (permit number, PER5195) against G. spilanthoides in aquatic situations in Queensland (rivers, streams and creeks) at a rate of 10mL/1L water until February 2005. This product can only be applied to G. spilanthoides by persons who are trained or experienced in the preparation, handling and use of agricultural chemicals (Land Protection, 2004). Redland Shire (Australia)
Redland shire has actively hand pulled senegal tea on Eprapah Creek (South east Queensland) for 10 years but progress is slow. Hand pulling is laborious, particularly for volunteer weed groups and working near water is hazardous. Tasman District (New Zealand)
G. spilanthoides has been designated as a 'Total control pest' by the the Tasman-Nelson Regional Pest Management Strategy. The strategy has its effect over the combined area that lies within the administrative boundaries of the Tasman District Council and Nelson City Council. The objective of the strategy is to eradicate known infestations of G. spilanthoides in the Tasman-Nelson region by 2006. Please see Hierarchy of Plant Designations for an explanation of designation terminology. Waikato Region (New Zealand)
G. spilanthoides is classified as an “Eradication Plant Pest” by Environment Waikato. Environment Waikato will directly manage and control it, as well as monitor the weed and providing identification and control information to the community.
Please see definitions for hierarchy of pest designations.
Management Resources/Links
4. Champion, P.D.; Clayton, J.S. 2001. Border control for potential aquatic weeds. Stage 2. Weed risk assessment. Science for Conservation 185. 30 p.
Summary: This report is the second stage in the development of a Border Control Programme for aquatic plants that have the potential to become ecological weeds in New Zealand. Importers and traders in aquatic plants were surveyed to identify the plant species known or likely to be present in New Zealand. The Aquatic Plant Weed Risk Assessment Model was used to help assess the level of risk posed by these species. The report presents evidence of the various entry pathways and considers the impact that new invasive aquatic weed species may have on vulnerable native aquatic species and communities.
Available from: http://www.doc.govt.nz/upload/documents/science-and-technical/SFC185.pdf [Accessed 13 June 2007] 8. National Pest Plant Accord, 2001. Biosecurity New Zealand.
Summary: The National Pest Plant Accord is a cooperative agreement between regional councils and government departments with biosecurity responsibilities. Under the accord, regional councils will undertake surveillance to prevent the commercial sale and/or distribution of an agreed list of pest plants.
Available from: http://www.biosecurity.govt.nz/pests-diseases/plants/accord.htm [Accessed 11 August 2005] Results Page: 1
|
