FACTSHEET BIOLOGICAL CONTROL OF

July 2010 Gorse For more information on weeds, including () use of biocontrol Gorse is a Weed of National Significance agents contact: Biocontrol agent: Gorse seed and a declared plant in South Australia. ( ulicis) Landowners have a legal responsibility to Your local NRM Board control gorse under the South Australian www.nrm.sa.gov.au BACKGROUND Natural Resources Management Act 2004. Regional NRM Boards coordinate and Visit the Biosecurity Gorse, also known as furze, is a spiny enforce local and regional control SA web page: shrub introduced from Europe as a hedge programs for declared plants. www.pir.sa.gov.au/bio plant. security/nrm_biosecuri It is a serious weed of bushland and forest HOW THIS BIOCONTROL WORKS ty/weeds plantations where gorse plants can out- The gorse seed weevil is native to western Ph 08 8303 9620 compete native plants and young forestry Europe. It is widely established in all areas trees, and increase the fire hazard along of Australia where gorse occurs, except in plantation edges. Or Weeds Australia: Western Australia. www.weeds.org.au The plant invades improved pastures, Adult are 1.8 to 2.5 mm long and resulting in lower carrying capacity, and are present on gorse all year round. They provides harbour for vermin. commence egg-laying in spring. It is expensive to control and requires The main damage results from larvae ongoing follow-up work. feeding on developing seeds within the Gorse is a perennial, evergreen legume pods. which can grow to 4 metres tall. Gorse seed weevil larvae have been It can live to around 30 years of age and a shown to damage 44% of the seed mature infestation can produce up to 6 produced during spring and summer, but million seeds per hectare each year. do not infest seed produced in autumn. Most seeds fall around the plant but they RELEASE OF AGENT IN SOUTH can be expelled to a distance of 5 metres. AUSTRALIA The seeds have a hard, water-resistant The gorse seed weevil was first discovered coating allowing them to remain dormant in in South Australia in 1939. the soil for up to 75 years. It is well established in the Adelaide and Mt Seeds are usually released in hot or dry Lofty Ranges NRM Region, and in most of conditions and mass germinations can the higher rainfall areas of the SA Murray occur after burning or mechanical Darling Basin Region. disturbance.

Gorse seed weevil pod pupae Gorse seed weevil adult (1.8 to 2.5 mm long) Image courtesy of W Chatterton TIAR Image courtesy of W Chatterton TIAR

Gorse infestations OTHER AGENTS USED ON GORSE The soft-shoot moth (Agonopterix ulicetella) has not yet been released in across SA Gorse thrips (Sericothrips staphylinus) NRM Boards South Australia. It is difficult to rear in have been released in the SA Murray quarantine and more laboratory testing is > Adelaide & Mt Lofty Darling Basin Region near Mt Pleasant to be conducted. The gorse pod moth Ranges: (2009), Palmer (2007 and 2009), (Cydia succedana) is nearing completion widespread in the Harrogate (2001), Eden Valley (2006), of host specificity tests. higher rainfall areas Macclesfield (2001 and 2006), Mt Barker (2007) and Meadows (2007). > Kangaroo Island: INTEGRATED CONTROL Of the 50 releases made since 2006 in small scattered Integrated weed management aims to infestations these areas, 40% appeared to have maintain or reduce weed densities to survived beyond the first year, though > Northern & Yorke: manageable levels by utilising a variety of there has been no spread from release common on roadsides control practices, including biocontrol plants at these sites. and watercourses in where appropriate. the south Gorse thrips feed on leaves. The impact on Glasshouse experiments have > Eyre Peninsula: potted gorse in glasshouses is high, yet demonstrated that the gorse thrips, in the same level of damage has not been very scattered combination with ryegrass competition and infestations in the observed in the field. grazing, can significantly reduce gorse south Gorse spider mites (Tetranychus seedling survival. lintearius) were first released in the > SA Murray Darling Integrated gorse control can utilise Basin: Adelaide and Mt Lofty Ranges Region in mechanical clearing, cultivation, isolated outbreaks in 2001 at Crafers and Lobethal. Since then herbicides, hand-pulling, fire, grazing, natural dispersal and intentional releases, the higher rainfall area pasture management and revegetation, in to the west especially through the Weed Warriors addition to biocontrol. > South East: program, have resulted in the mites In inaccessible locations, or where there is rare in the north, establishing in most high rainfall areas of a risk of damage to sensitive native scattered in the south the Adelaide and Mt Lofty Ranges and SA Murray Darling Basin Regions. vegetation, conventional control methods may be difficult or impossible to implement. Gorse spider mites were established in the Biocontrol may then be the only South East and present in the Northern management option however biocontrol and Yorke Regions, but recent alone will not eradicate the weed but slow eradication/control programs have its rate of spread and allow more time for destroyed many of these sites. control by other means. Spider mites are sap feeders on the leaves and stems of gorse. Extensive feeding REFERENCES / LINKS pressure can kill shoots, reduce plant Declared Plants of South Australia growth and biomass, and abort the production of flowers. Studies and Integrated Weed Management anecdotal evidence have shown that the Gorse Weed Identification Notes spider mite can have a large impact on plant vigour in the first 12 months before Biocontrol of Gorse with Gorse Thrips predators, such as the introduced Chilean Biocontrol of Gorse with the Gorse Spider mite (Phytoseiulus persimilis) and the Mite native ladybird (Stethorus histrio), start to regulate the colony. Biocontrol of Gorse with the Gorse Seed Weevil Fungal pathogens are being investigated as agents against gorse and CSIRO will Biological Control of Gorse conduct host specificity tests against Weed of the Month: Ulex europaeus potential candidates.

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