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DEPARTMENT OF PRIMARY INDUSTRIES

WHEEL CACTUS

Opuntia robusta REGIONALLY PROHIBITED WEEDS INFORMATION SHEET

Plant biology Invasive cause significant detrimental impacts in Victoria. They are a serious threat to agricultural production, biodiversity Type of weed: and social values. The Department of Primary Industries (DPI) Agricultural, garden escapee is implementing a risk based, biosecurity approach to the management of invasive plants. Government intervention is Life form: focused on coordinated, statewide actions which prevent new An erect succulent shrub growing to 1 to 2 m high high-risk species becoming established while seeking to contain targeted, established high-risk species. Adopting this approach Stems: will provide the greatest returns on investment. All stakeholders Consist of a series of blue-green fleshy segments (also known as joints, pads or need to play their part in preventing new high-risk invasive cladodes) which are commonly thought of plants from establishing and spreading. as leaves but are really flattened stems

Segments are circular growing, to 40 cm in In Victoria, declared noxious weeds are steps to prevent the growth and diameter, flat, glabrous and armed with classified under the Catchment and spread of Regionally controlled weeds tufts of numerous barbed bristles Land Protection Act (CaLP) 1994 as: on their land. (glochids); commonly found with one to five sharp spines growing to 4 cm long State prohibited weeds (SPW) Restricted weeds arising from each areole These weeds pose a significant threat This category includes plants that pose to Victoria and when infestations occur an unacceptable threat to this State or Leaves: they can reasonably be expected to be to other parts of if they were Small, scale-like, produced beneath the eradicated. The Victorian Government to be sold or traded in Victoria. Trade areoles on young segments only; which are is responsible for their eradication. in these weeds and their propagules, shed as segments when mature either as plants, seeds or contaminants Regionally prohibited weeds (RPW) in other materials is prohibited. Flowers: These weeds are not widely distributed Yellow petals with reddish streaks on the in a region but are capable of The high-risk invasive plants declared back spreading further. It is reasonable to as RPWs are among the highest expect that they can be eradicated threats to regional biosecurity at a Flowers are about 5 to 8 cm in diameter, sessile, with a fleshy base, produced mostly from a region. Land managers must catchment scale. on the upper margins of terminal segments take all reasonable steps to eradicate regionally prohibited weeds The purpose of this fact sheet is to: • Provide basic identification Fruit: on their land. Pink to purple and barrel-shaped growing to information on a RPW 8 cm long and 6 cm in diameter, with dark Regionally controlled weeds (RCW) • A summary of best practice control red flesh bearing tufts of fine barbed hairs These weeds are usually widespread measures, hygiene and prevention or bristles in areoles and are considered important in a information particular region. Land owners have • To inform landholders of their the responsibility to take all reasonable regulatory responsibilities

Catchment Management Legislative status in Victoria Authority Boundaries Regionally Prohibited in the Mallee in Victoria Port Phillip & Westernport CMA Regionally Controlled in the Mallee, North Central North East Wimmera Goulburn Broken North Central, Wimmera and North

East Gippsland East CMAs Port Phillip & Westernport Glenelg Hopkins West Gippsland Corangamite Restricted in the Glenelg Hopkins, Corangamite, Goulburn Broken, West Gippsland and East Gippsland CMAs CS22 Wheel Cactus 11/2/10 3:53 PM Page 2

WHEEL CACTUS robusta

Impacts Ecosystems and waterways Agricultural and economic The root system of the Wheel Cactus is shallow and Wheel Cactus is not a weed of cropping or intense fibrous. In dense patches, aerial growth provides good grazing land, however animals avoid the because of ground cover. its spines and dense patches may limit grazing capacity.

The weed grows densely, forming impenetrable barriers; Presence of the weed is not likely to affect land value. stands can hinder growth and regeneration of indigenous plants, smaller shrubs and ground flora, resulting in a Social value and health major impact on lower stratum and a minor impact on Patches of Wheel Cactus grow densely, forming an mid stratum flora. impenetrable barrier; in some instances the plant was used as hedging. Where established, the weed is most Wheel Cactus is not usually grazed by stock because of likely to restrict human access. its stout spines; in dense patches, the plant could hinder access to water and reduce food available for fauna. The plant may also affect some recreational activities.

Being long-lived, patches of the plant also provide The barbed bristles of the Wheel Cactus are sharp, readily effective and permanent harbour for pest animals such as penetrating human skin causing severe irritation; they are rabbits. difficult to remove.

Preferred habitat Wheel Cactus prefers arid and semi-arid areas in warm- temperate and sub-tropical regions, where it grows well on shallow granite soils. It has become weedy in isolated areas of Victoria, particularly in the north central region. The plant is drought-resistant.

Rate of growth and spread Once established, individual Wheel Cactus plants can live for several decades.

The weed produces viable seed, which can be spread in the droppings of birds, foxes and other animals over large distances.

The plant reproduces by seed and also propagates from branch segments.

Seedbank/propagule persistence Wheel Cactus produces numerous fruits, with each fruit containing numerous seeds.

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WHEEL CACTUS Opuntia robusta

Growth Calendar

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Flowering Seeding Germination Dormancy Treatment Prevention – what you can do Prevention of infestations is the best option for weed • before leaving infested areas and before being allowed control. To minimise the risks you can: to enter areas that are free of the weed • Ensure imported fodder, grain, gravel, sand and soil is • Weed-free buffer zones should be maintained between free of seed contamination before purchase, sale or infested and non-infested land movement • All vehicles and equipment should be thoroughly It is an offence to sell, transport or deposit onto land any cleaned to remove any soil, seed or parts of the plant material contaminated with noxious weeds.

Eradication – how you can help DPI’s aim is to eradicate regionally prohibited weeds from a fruit. The plant has a high moisture content and does not region. Following these principles will assist with that goal: burn easily. • Treat all plants before seeding • Use a combination of control methods As much of the root system as possible should be removed when using grubbing or cultivation as methods • Keep clean areas free of weeds and manage them to of control. It is essential to conduct follow-up treatment prevent weed invasion of seedlings as reinfestation will occur. • Remain vigilant: monitor and remove any new incursions or emerging plants Cutting and grubbing of the plants is effective but care • Be persistent. Regular follow-up and inspections are a needs to be taken when removing and disposing of plant vital component of any weed control program material. • Ensure re-infestation does not occur from the original source Cultivation techniques are an effective form of control if repeated each time new growth appears. This method is Physical removal and burning are the most effective generally not practical as the weed is often located on methods of control for Wheel Cactus, but care must be rocky, non-arable land. taken to collect and destroy all dislodged segments and

Working together A successful eradication program should consider a range DPI may direct landowners to undertake specific control of control techniques appropriate for addressing the activities to ensure methods are used that are capable of growth stage and size of an infestation. The control destroying plants and preventing their spread. techniques need to be integrated into a strategy to gain best long-term control. Landowners must use the method or methods prescribed as directed by DPI. In most cases the landowner will be Some control methods are only effective if used in able to choose from a variety of options appropriate for combination with other control options as part of a use in their particular situation. long-term management program. If used in isolation, these methods may not provide the desired outcome of eradication of an infestation.

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WHEEL CACTUS Opuntia robusta

Chemical Control Under Victorian legislation there are controls on the use of Choose only products registered for use in your particular agricultural chemicals which include requirements for situation. Read the product label carefully and follow all keeping records of chemical applications. It is the label instructions. responsibility of the user to be familiar with this legislation. Chemical retailers can provide information on chemical Farm chemicals are registered for specific uses. Each products registered for your situation. chemical has a ‘product label’, which documents the approved use and the approved rate of use within each They can also supply a ‘material safety data sheet (MSDS)’ State. This label is important in determining the which outlines the health and safety information about a appropriateness of chemical use. product. This information is also available from chemical manufacturers and product labels are available from the Other controls include the requirement to possess an Australian Pesticides and Veterinary Medicines Authority Agricultural Chemical Users Permit to allow use of certain website: http://www.apvma.gov.au chemical products and restrictions of use of certain chemical products in Agricultural Chemical Control Areas. For further Information please refer to the Information Websites to visit: Note Ag1210 “Chemical Use in Victoria – What I can and http://www.dpi.vic.gov.au/chemicalstandards can’t do” or the Chemical Standards branch website: http://www.apvma.gov.au http://www.dpi.vic.gov.au/chemicalstandards

How to maximise your efforts • Work with your neighbours • Make a long term management plan and stick to it • Review and amend your plan as appropriate • Seek professional advice • Aim to treat every plant • Don’t let plants set seed • Remain vigilant and always follow up the previous season’s work

References

Blood, K. 2001, Environmental weeds. a field guide for Muyt, A. 2001, Bush invaders of south-east Australia. a guide to SE Australia, CH Jerram, Science Publishers, Mt Waverley, Victoria, the identification and control of environmental weeds found in Australia south-east Australia, R.G. & F.J. Richardson Victoria.

Carr, G.W., Yugovic, J.V. and Robinson, K.E. 1992, Environmental Parsons WT & Cuthbertson EG 1992, Noxious Weeds of Australia, weed invasions in Victoria: Conservation and management Inkata Press, Melbourne and Sydney. implications, Department of Conservation and Natural Resources and Ecological Horticulture, Victoria. Parsons, W.T. and Cuthbertson, E.G. 2001, Noxious weeds of Australia, 2nd edn, Inkata Press Melbourne & Sydney.

If you would like to receive this information/publication in an accessible format (such as large print or audio) please call the Customer Service Centre on 136 186, TTY 1800 122 969, or email [email protected]. Published by the Department of Primary Industries, Landscape Protection Portfolio, February 2010. © The State of Victoria 2010. This publication is copyright. No part may be reproduced by any process except in accordance with the provisions of the Copyright Act 1968. Authorised by the Department of Primary Industries, 1 Spring Street, Melbourne 3000. ISBN 978-1-74217-675-8 (print) ISBN 978-1-74217-676-5 (online) Disclaimer 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. For more information about DPI go to www.dpi.vic.gov.au or phone the Customer Service Centre on 136 186.