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

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

Identification │ The problem │ More information │ Control methods │Using pesticides │Disclaimer

A native of Mexico and the United States, Cylindropuntia imbricata - rope pear (also known as Devil’s rope) has been widely distributed in New South Wales as a garden plant. An easy plant to grow, and one that requires very little moisture, rope pear survives well in the western areas of the State.

 Rope pear spreads by fruit and segments that break off the parent plant and wash along waterways.  This photo taken in 1988 shows a major patch of rope pear near the McIntyre River, in the Elsmore area near Inverell, New South Wales.

THE PROBLEM

Rope pear is a very thorny cactus which can cause injury to humans and to animals.  Segments are mainly spread by floodwaters, and in some cases by being rolled along bare ground by strong winds.  These segments form into new plants.  Rope pear is comparatively slow-growing, but as shown in the above photograph, it can eventually become thick enough to impede access and to reduce stock-carrying capacity. 

 [CLICK ON PHOTOS FOR A LARGER VIEW]

IDENTIFICATION

This cactus is commonly called “rope pear” because of its rope-like appearance.  The plant grows to a height of 2 to 3 metres.  It is made up of strong, woody segments – the outer segments (and fruit pods) break off easily to form new plants.  The plant has 2-3 cm thorns, enclosed in yellowy sheaths.  Rope pear produces very attractive purple flowers – no doubt one of the reasons for its appeal as a garden plant. The main growing period for the plant is in October each year. 

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CONTROL METHODS

Chemical treatment of rope pear is effective, because the plants are relatively easy to find.  Biological control is another practical and cost-effective means of control, especially in the warmer and drier areas of western New South Wales.  Repeated ploughing/cultivation destroys rope pear (the pieces eventually give up if damaged and/or disturbed often enough).  Burying or burning is an option for small infestations.

HERBICIDES – Current registrations for Cactaceae family:

STOP PRESS:  The botanical name for rope pear has been changed from Opuntia imbricata to Cylindropuntia imbricata.  Not all herbicide labels have been updated by the manufacturers to reflect this change.  So, please check the labels on any new herbicide containers to ensure registration applies.

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.

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BIOLOGICAL – not recommended for small or isolated areas (you're much better off to get rid of the plants by chemical or manual means) but cochineal insects are very useful for controlling thick patches - especially in dry and warmer areas:

Cochineal insects (Dactylopious tomentosus) are slow, but they can achieve an acceptable level of control if they are given some assistance.  Once established on individual plants, the adults provide a continuous supply of new insects to attack new growth and surrounding plants.  This photograph (left) shows cochineal at work on rope pear - the white material is the protective cover for the adult cochineal - dozens of tiny (red) "crawlers" (young cochineal) can be clearly seen against the plant's green background.

The use of cochineal insects simply involves the manual transfer of cochineal-infested segments, like the one in the photo, into plants that do not contain cochineal insects! All you need is a bucket and a pair of tongs...
 
Assisting the further distribution of cochineal?  Cochineal start their lives as tiny, crawling insects, venturing off to locate a new food source.  Sometimes they climb to the top of a blade of grass and wait for the wind to blow them to a new area.  They can travel some kilometres in this way, but of course they don’t always find the target!
 
Cochineal insects can only crawl along the ground for about 4 or 5 metres (or to the first large crack in the ground, eg as in black soil situations.  Generally, they need our assistance to get them into new pear areas.  A bucket and a pair of tongs, and the simple transfer of infected segments into new plants is the answer.

Tips to help the cochineal? 

• Always remember that cochineal insects are very delicate.  They don’t like cold and wet weather.  When you put the insects into a new plant (especially in the approach to winter) give them some protection from the elements.  Cover the infected segments with parts of the plant, or branches, bark, cow pads etc.

• Covering newly-infected plants with cardboard, plywood or even a bit of old corrugated iron will offer the cochineal insects useful protection from the weather.  You’ll be surprised how well the insects build up in this situation. 

• Another trick is to breed the insects indoors, in readiness for release in early summer, the optimum time for release.  Store infected plant material in cardboard boxes in a dry, warm area.  Over a period of 6 to 8 weeks, you’ll have good supplies to put out when the weather warms up.

• After cochineal insects become established on the plants, CUT SOME OF THE LARGER PLANTS DOWN - CAREFULLY.  Cutting the plant off at or near ground level severs the plant's food supply and reduces its resistance to the tiny cochineal insects. Stack the severed plant parts around the base of the plants to keep the material and the insects together.

WARNING: The process of cutting down rope pear plants can transform thorny segments into dangerous projectiles. Take care, and always wear appropriate protective clothing!  

USE THE RIGHT COCHINEAL…  Tiger pear, common pear and rope pear cochineal all look the same.  But, they’re each specific to their host plants.  Only rope pear cochineal – Dactylopious tomentosus - works on rope pear!

MORE INFORMATION

Cochineal.htm on this website.  Information on individual prickly pear species is also included in this website.  Return to Weeds List for harrisia cactus, velvety tree pear, prickly pear history etc. 

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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 - 7/9/02

Send mail to northwestweeds@aapt.net.au with questions or comments about this web site.
Copyright © 2007-2013 Last modified: 23-Feb-2012 - North West Weeds