Preventative measures: It is suggested that planting of this species be banned, except where it can be contained, and
that dumping of garden waste on vacant lots be prohibited.
A Risk Assessment of Sphagneticola trilobata (Wedelia trilobata) for Hawai‘i and other Pacific islands was prepared by Dr. Curtis Daehler (UH Botany) with funding from the Kaulunani Urban Forestry Program and US Forest Service. The alien plant screening system is derived from Pheloung et al. (1999) with minor modifications for use in Pacific islands (Daehler et al. 2004). The result is a score of 13 and a recommendation of: "Likely to cause significant ecological or economic harm in Hawai‘i and on other Pacific Islands as determined by a high WRA score, which is based on published sources describing species biology and behaviour in Hawai‘i and/or other parts of the world."
A Risk assessment of
Sphagneticola trilobata (Wedelia trilobata) for Australia was prepared by Pacific Island Ecosystems at Risk
(PIER) using the Australian risk assessment system (Pheloung, 1995). The result is a score
of 6 and a recommendation of: reject the plant for import (Australia) or species likely to
be a pest (Pacific).
Physical: The Land for Wildlife program south-east Queensland, recommends 'scarifying' for small patches of soil dominated by weeds like wedelia - the top few centimetres of soil are removed using a suitable tool such as a fire hoe. The aim is to remove soil-stored seed. Do not leave disturbed area open for reintroduction of weeds. Mowing or slashing of wedelia infested areas should be avoided as this may cut the plants into smaller pieces that can develop into new plants, and increases the risk of spreading to new areas, (Liebregts, 2001).
Chemical: Langeland and Stocker (2000), suggest treating small patches with 2% Roundup; and large, dense populations by broadcast-spraying 5% Roundup (with follow-up treatments as needed). Or 1/4-1.0% Garlon 4 in water.
Location Specific Management Information
The Niue Department of Agriculture, Forestry and
Fisheries, implemented an eradication programme of
the weed Sphagneticola trilobata commonly known as wedelia. Surveys conducted between 27 February and 8 March showed that wedelia was
found at 35 sites. The total coverage of the weed was estimated at 1 hectare (10,000 sq. m.). The
area of the infestation varied between a few to 1000 sq.m.
The campaign was started in March 2001. Trial applications of the systemic herbicide Round Up (a.i. glyphosate; at 10ml/l) by knapsack sprayer were carried out on identified sites.
Simultaneously, public awareness was raised through a TV interview (both in
English and translated into Niuean), and by designing and placing signboards
at strategically located wedelia infested sites around the island.
The effectiveness of the
herbicide Round Up in controlling dense areas of the weed was found to be
unsatisfactory, and the use of Gramoxone (a.i. paraquat) was advised to
rapidly kill foliage and make underlying stems and shoots more accessible to
following applications of Round Up.
Details of the programme are available in the following documents:
1. Daehler, C.C; Denslow, J.S; Ansari, S and Huang-Chi, K., 2004. A Risk-Assessment System for Screening Out Invasive Pest Plants from Hawaii and Other Pacific Islands. Conservation Biology Volume 18 Issue 2 Page 360.
Summary: A study on the use of a screening system to assess proposed plant introductions to Hawaii or other Pacific Islands and to identify high-risk species used in horticulture and forestry which would greatly reduce future pest-plant problems and allow entry of most nonpests.
3. IUCN/SSC Invasive Species Specialist Group (ISSG)., 2010. A Compilation of Information Sources for Conservation Managers.
Summary: This compilation of information sources can be sorted on keywords for example: Baits & Lures, Non Target Species, Eradication, Monitoring, Risk Assessment, Weeds, Herbicides etc. This compilation is at present in Excel format, this will be web-enabled as a searchable database shortly. This version of the database has been developed by the IUCN SSC ISSG as part of an Overseas Territories Environmental Programme funded project XOT603 in partnership with the Cayman Islands Government - Department of Environment. The compilation is a work under progress, the ISSG will manage, maintain and enhance the database with current and newly published information, reports, journal articles etc.
5. Niue DAFF, 2001. Wedelia Leaflet. Department of Agriculture, Forestry & Fisheries (DAFF), Niue. With assistance from SPC - Plant Protection Service.
8. Thaman, R.R. 1999. Wedelia trilobata: Daisy invader of the Pacific Islands. IAS Technical Report 99/2. Institute of Applied Science, University of the South Pacific, Suva, Fiji Islands.
Summary: This paper is a preliminary account of the status in the Pacific Islands of Wedelia trilobata (L.) Hitch., a recently introduced ornamental groundcover plant that has become an extremely invasive weed in many areas, and has the potential to become one of the most environmentally destructive weeds of the Pacific Islands. It is suggested that Wedelia trilobata should be immediately declared a serious noxious weed, should be restricted from introduction into new islands and habitats, and, where possible, should be exterminated from islands and habitats where it has not gained a foothold.
The paper describes Wedelia trilobata and discusses what is known about its introduction and spread in some island countries, the habitats in which it thrives and has become naturalized or invasive, and the present and potential threat that it poses to island ecosystems and indigenous species. Actions are suggested that could be taken to control the introduction and spread of Wedelia trilobata to islands and habitats where it does not yet exist, and to eradicate it from areas where it is not yet out of control.
12. Wilson, Colin, Wildlife Management Officer, Department of Infrastructure, Planning and Environment, Parks & Wildlife Service, Northern Territory, Australia.
Summary: Compilor of original GISD profile of Chromoleana odorata.
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