North West Weeds 
          Your local guide to local noxious weed control (NSW, Australia)

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North West Weeds
ABN 16 052 158 879
Postal address:
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BINGARA
NSW 2404

Identification │ The problem │ Locality Map │ Control methods │Using pesticides │Disclaimer

Harrisia cactus (Harrisia martinii) is a native of the Americas, no doubt introduced into Australia for its appeal as a garden plant.  Harrisia became a serious pest problem in parts of Queensland, eventually spreading into the Boggabilla-Yetman areas of New South Wales.

Harrisia cactus is spread by seed.  The plant can begin to produce seed at age 6 months and from then on can continue to produce fruit almost all year round.  Each fruit contains about 800 seeds encased in a sweet, sugary substance which is extremely popular with birds, emus and pigs.

Harrisia cactus has continued to spread into various parts of north-west New South Wales.  The sharp spines are something of a hazard to humans and animals. Harrisia is hard to control because of its seed-producing ability.  Birds and foxes carry the seed for miles. Goannas and ants also enjoy the sweet fruit.  Most seeds seem to germinate. [Click on photo for a closer look at a typical harrisia plant]

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IDENTIFICATION

Harrisia cactus is a low-growing, jointed, cactus plant.  Its runners spread out like the tentacles of an octopus.  When the runners touch the ground they take root.  The fruit – about “passionfruit-size” – is bright red when ripe.  It splits open to reveal sweet seeds to birds, animals and ants.

THE PROBLEM

Harrisia cactus can cause painful injury to animals or humans who accidentally walk into or otherwise touch a plant.  It is a prolific seeder, spreads quickly, and has the ability to eventually take over large areas of grazing country.

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CONTROL METHODS

Ploughing is probably the only means of eradication.  Harrisia cactus cannot survive on lands under constant cultivation [NB.  State laws apply in respect of land clearing.]

Burning. Tops of plants are easily killed, butts go deep into the ground and therefore require extra heat. Burning is really only appropriate for small infestations.  [NB.  Subject to compliance with local bushfire restrictions].

Biological control using a mealybug (Hypogeococcus festerianus) has been effective in warmer areas of Queensland and is now being used with varying degrees of effectiveness to control Harrisia infestations in New South Wales.  The insects have to be manually transferred into uninfected plants. The main problem with biological control is that the mealybug does not have the capacity to spread as efficiently as do new seedling plants. The seeds can be spread kilometres by birds and animals, whereas the mealybug can only travel a matter of metres.  And, cactoblastis or cochineal are INEFFECTIVE on Harrisia cactus.

Chemical treatment is effective, but must be regularly undertaken.  According to NSW DPI’s excellent booklet “Noxious and Environmental Weed Control Handbook 2004/2005”, herbicide treatments registered for use in New South Wales include:

NB  Most Harrisia cactus in New South Wales is found near the border with Queensland, mainly in the Boggabilla area.  For those NSW property owners who also have land north of the border, please note there are a number of chemicals registered for use in Queensland only.  These include Tordon DSH® (2.5 L/100 L water) and Lantana DP 600® (1L/60 L water).  Check labels for full directions.

IMPORTANT:  USE OF PESTICIDES – ALWAYS READ THE LABEL

Pesticides must only be used for the purpose for which they are registered and must not be used in any other situation or in any manner contrary to the directions on the label.  Never use a herbicide in any way contrary to the label recommendations.

MORE INFORMATION

Queensland Department of Primary Industries has had a long involvement with managing this predominantly Queensland cactus… see their informative webpage www.nrm.qld.gov.au/pests/weeds/declared_plants/harrisia_cactus.html

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DISCLAIMER:   The information contained in this web site is based on knowledge and understanding at the time of writing. However, because of advances in knowledge, users are reminded of the need to ensure that information upon which they rely is up to date and to check currency of the information with the appropriate officer of North West Weeds or the user’s independent adviser.
LRT 30/10/06
 

Send mail to lestanner@aapt.net.au with questions or comments about this web site.
Copyright © 2007-2008 Last modified: 25/11/07 - L R Tanner