South African Weed Orchid 2: Management (DPI Vic)

April, 2002 South African weed orchid: LC0274 Management ISSN 1329-833X Compiled by Jill Fleming (Horsham)

This Landcare Note outlines options for the management 2005 with 1 ha currently infested in the Wimmera of the South African orchid, Disa bracteata (Monadenia Catchment Management Authority region. It gained this bracteata). status as it was identified as a significant threat to environmental values and all known infestations in the Common and scientific names Wimmera could be treated within three years to achieve South African weed orchid, African weed orchid, South containment and/or eradication. African orchid or Brown finger orchid. Disa bracteata (Sw) T.Durand & Schinz. Family Orchidaceae (orchids). Background The largest family in the world, orchids represent nearly a See the Landcare Note: South African weed orchid – tenth of all flowering plants. Orchids occupy a diverse identification, for a description and illustrations of this range of habitats and are most diverse and abundant in the plant. moist tropics. They are important ecologically having Status symbiotic relationships with soil fungi and most are dependent on specific insect pollinators. There are five main infestation sites in Victoria; Black Range – Stawell, Lake Eppalock – Bendigo, Deans Marsh D.bracteata first appeared in South Australia, in 1988, – Otways, Rowsley Valley – Bacchus Marsh and the spreading rapidly in the 1990’s. The problem has at least Lower Glenelg National Park, which are currently under a doubled annually and the local spread has averaged some control and monitoring program. The other known 10km/yr north and south. Current knowledge is that there infestations throughout the state have been contained and are at least 10ha infested in Victoria. The first recorded have long term monitoring programs in place. infestation in Victoria was in the Rowsley Valley near Bacchus Marsh in 1991. Infestations in Victoria are also The South African orchid is not a proclaimed species likely to be the result of garden escapes. anywhere in Australia. It as been identified as a New and Emerging weed in the Wimmera Weed Action Plan 2000-

Figure 1. Known infestations of South African orchid in Victoria.

Properties Chemical information D.bracteata is autogamous (self-pollinating) and each There is no chemical herbicide registered for the control of plant is capable of producing tens of thousands of airborne South African orchid in Victoria. seeds, which have a high probability of dispersing greater than 1km from the mother plant. The South African orchid Under Victorian legislation there are controls on has the potential to impact on native understorey flora, various aspects of the uses of agricultural chemicals. Some particular uses are prohibited and some require especially rare and endangered plants. It grows readily in permits. Users of certain agricultural chemicals are competition with a wide range of other flora including required to obtain an Agricultural Chemical User grasses; it invades bushland and pastures. The weed Permit (ACUP) or work under direct supervision of an crowds out other species will grow in all light conditions ACUP holder. Additional restrictions on the use of and is not fussy about soil types. The plant is also tolerant some herbicides apply to particular geographic areas to fire, frost and drought and is consumed by sheep, cattle, known as Chemical Control Areas (CCA). horses and kangaroos. It is the responsibility of chemical users to familiarise themselves with these controls. See Agriculture Note Dispersal AG0626: Agricultural chemical user permits (ACUP) Dispersal from property to property and within properties and chemical control areas (CCA) for further appears to be mainly by transfer on vehicles, machinery information. and clothing. Before transporting any earth moving Contact the Regional Chemical Standards Officer of equipment or vehicles from a known infestation site to a the Department of Sustainability and Environment if new site, remove all seeds and soils from machinery by further advice is required. scraping, brushing and washing down, ensuring clothing and shoes are free of seeds. Further information Because of the fine dust-like seeds, the possible area of For further technical advice please contact a Catchment contamination due to the wind is endless; we cannot Management officer at your local Department of control where the wind may disperse the seeds, however Sustainability and Environment office. with education and awareness will assist in the control of South African orchid. If land managers carry out regular monitoring and good weed hygiene practices, the threat of this weed becoming established can be significantly reduced. Management DSE commenced a program to eradicate the South African orchid 1996 in the Lower Glenelg National Park and in the Parwon Valley. Long-term management is required as this weed takes three years to develop from seed to flowering plant and the seeds may be viable for up to seven years. Prevention is the best and most effective method of weed control. Landholders and managers need to continually inspect their properties and keep informed of possible new threats. If an infestation is located on your land, all measures need to be ensured that the spread is minimised. Manual removal has proven the most effective method of control and it is encouraged that the weed is removed before flowering in October. Figure 2. Grubbing South African Orchid at Fulham Reserve. Gently bend the stem into a plastic bag, ensuring all seeds Acknowledgment only fall into the bag. Using a screwdriver or similar tool Prepared by Jill Fleming with the kind assistance of Ian Faithfull lever up the tubers. Dispose of responsibly in local garbage (Keith Turnbull Research Institute), Stuart Lardner (NRE collection. Horsham), Mark Farrer and Celeste Ellice (NRE Stawell) and A thorough search of the immediate area may also locate Kate Blood (Weeds Cooperative Research Centre). smaller less developed plants. Follow-up inspections should be undertaken to ensure there is no regrowth and spread from seeds.

This publication may be of assistance to you but the State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication.