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This Weed Risk Management Assessment uses a series of questions to arrive at scores for weed risk and feasibility of coordinated control for this weed, and displays the necessary management actions derived from these scores.

This information is then used to make decisions about the introduction, prioritisation and declaration of this weed in New South Wales.

Weed (Scientific name) Cylindropuntia species (all species in genus naturalised in NSW)
Weed (Common name) various prickly pears including Hudson pear
Region All of NSW
Management area Mostly rangeland in western NSW
Landuse 2.1 Grazing natural vegetation
Assumptions Cylindropuntia, Cactaceae. Standard weed management is limited. Varied stocking rates most common. Fire used in some instances. Very little use of broad-scale herbicide applications and cultivation.  Density in land use - medium.
Weed Risk
InvasivenessScore      Total Answers Source and comments
Q1. What is the ability of the weed to establish amongst existing plants?


Do not know Do not know' - more research is needed.
Q2. What is the weed's tolerance to average weed management practices in the land use?


95% + weeds survive common management J. Hosking personal observations.
Q3. What is the reproductive ability of the weed in the land use?


  Only one species is known to produce viable seed.  The responses for a. and b. best reflect the 'average for the genus'. Vegetative reproduction is common in all species.
(a) Time to seeding 0.0 >3 yrs/never
(b) Annual seed production 1.0 Low
(c) Vegetative reproduction 2.0 Frequent
Q4. How likely is long-distance dispersal (>100m) by natural means?


  Johnson et al. (2009)
(a) Flying animals 0.0 Unlikely
(b) Other wild animals 2.0 Common
(c) Water 2.0 Common
(d) Wind 0.0 Unlikely
Q5. How likely is long-distance dispersal (>100 m) by human means?


  Johnson et al. (2009)
(a) Deliberate spread by people 1.0 Occasional
(b) Accidentally by people and vehicles 2.0 Common
(c) Contaminated produce 0.0 Unlikely
(d) Domestic/farm animals 2.0 Common



ImpactsScore      Total   
Q1. Does the weed reduce the establishment of desired plants?


Do not know Do not know'

Q2. Does the weed reduce the yield or amount of desired vegetation?


Do not know Do not know'
Q3. Does the weed reduce the quality of products, diversity or services available from the land use?


Low Based on Johnson et al. (2009)…and degrades appearance of areas where it infests
Q4. What is the weed's potential to restrict the physical movement of people, animals, vehicles, machinery and/or water?


Medium Based on Johnson et al. (2009).
Q5. What is the weed's potential to negatively affect the health of animals and/or people?


Medium Based on Johnson et al. (2009).

Q6. Does the weed have major positive or negative effects on environmental health?


  References do not mention any major environmental health effect.
(a) food/shelter 0.0 Minor or no effect
(b) fire regime 0.0 Minor or no effect
(c) altered nutrient levels 0.0 Minor or no effect
(d) soil salinity 0.0 Minor or no effect
(e) soil stability 0.0 Minor or no effect
(f) soil water table 0.0 Minor or no effect



Potential distribution Total   
Q1. Within the geographic area being considered, what is the percentage area of land use that is suitable for the weed?


40-60% of land use Estimate (partly based on C. rosea map done by Royce Holtkamp and John Scott - not published)

Comparative weed risk score



Weed risk category


Feasibility of coordinated control
Control costs Score      Total   
Q1. How detectable is the weed?


  Johnson et al. (2009)
(a) Distinguishing features 1 sometimes distinct
(b) Period of year shoot growth visible 0 > 8 months
(c) Height at maturity 1 0.5 - 2 m
(d) Pre-reproductive height in relation to other vegetation 1 similar height
Q2. What is the general accessibility of known infestations at the optimum time of treatment?


medium Personal observations.
Q3. How expensive is management of the weed in the first year of targeted control?


  Based on Johnson et al. (2009).
(a) Chemical costs/ha 3 high ($250-$500/ha)
(b) Labour costs/ha 2 medium ($100-$249/ha)
(c) Equipment costs 1 low
Q4. What is the likely level of participation from landholders/volunteers within the land use at risk? 2.0 low Personal observations.
Total 6.7   
Persistence Score      Total   
Q1. How effective are targeted management treatments applied to infestations of the weed?


low Based on Johnson et al. (2009).
Q2. What is the minimum time period for reproduction of sexual or vegetative propagules?


< 6 months Johnson et al. (2009)
Q3. What is the maximum longevity of sexual or vegetative propagules?


do not know Do not know' - this is a research gap.
Q4. How likely are new propagules to continue to arrive at control sites, or to start new infestations?


  Based on Johnson et al. (2009) - from infested sites.
(a) Long-distance (>100m) dispersal by natural means 2 frequent
(b) Long-distance (>100m) dispersal by human means 2 frequent
Total 9.1   
Current distribution Total   
Q1. What percentage area of the land use in the geographical area is currently infested by the weed? 0.5 1-5% of land use Relatively few areas with problems  - BGT (2010).  This score may be lower?
Q2. What is the number of infestations, and weed distribution within the geographic area being considered? 1.0 scattered The score that best suits the genera across NSW.
Total 1.3   
Comparative feasibility of coordinated control score 76
Feasibility of coordinated control category Low
Management priority category Manage weed
Calculation of overall uncertainty score 10%
Positive impacts Originally introduced into Australia as an ornamental but not used as such now.
References/Other comments
Botanic Gardens Trust (2010). PlantNET - The Plant Information Network System of Botanic Gardens Trust, Sydney, Australia http://plantnet.rbgsyd.nsw.gov.au (Accessed 3 May 2010).
Johnson, S. B., Hosking, J. R., Chinnock, R. J. and Holtkamp, R. H. (2009).  The Biology of Australian Weeds. 53.  Cylindropuntia rosea (DC.) Backeb. and Cylindropuntia tunicata (Lehm.) F.M.Knuth (Cactaceae).  Plant Protection Quarterly, 24, 42-49. 

The species included in this assessment are (alphabetically) (BGT 2010)
Cylindropuntia fulgida var. mamillata
Cylindropuntia imbricata
Cylindropuntia kleiniae
Cylindropuntia leptocaulis
Cylindropuntia prolifera
Cylindropuntia rosea
Cylindropuntia spinosior
Cylindropuntia tunicata

Assessment by Dr Stephen Johnson, Weed ecologist, I&I NSW, 3 May 2010.  Previous consultation with Dr John Hosking I&I NSW, Tamworth occurred.

Biocontrol agent - the cochineal insect has been introduced for at least one species (C. imbricata) and a different strain will be introduced for C. rosea during 2010.

There are a number of knowledge gaps for species in this genera and the risk assessment is based on the review by Johnson et al. (2009) and personal observations of Dr John Hosking.

Declaration to continue to support biological control efforts.
Once recognised by people as part of the Opuntia genus.