Opuntia spp. other than O. ficus-indica
Common pest pear, spiny pest pear, tiger pear, drooping tree pear, velvety tree pear, Westwood pear
- Leafless succulent shrub.
- Spiny and pear-shaped fruit.
- Stems divided into segments (pads or joints).
- Flowers large and vary from yellow, orange, red, pink, purple to white seen during spring.
- Fruits varying from red, purple, orange, yellow to green.
- Prefers subhumid to semi-arid areas in warm temperate and subtropical regions.
- Grows mainly along streams, banks and roadsides.
- Native to the Americas.
- Infestations of common prickly pear covered 4 million hectares by 1900, 24 million ha by 1920 and advanced at a rate of 400,000ha per year.
Drought resistant because of their succulent nature, their lack of leaves and their thick, tough skins. These features result in plants that use the majority of their internal tissues for water storage and their outer parts to reduce water loss and damage by grazing and browsing animals. They can remain vigorous in hot, dry conditions that cause most other plants to lose vigour or even die. Some species develop underground bulbs that enable the plant to resist fire and mechanical damage.
Reproduce both sexually and asexually. Seeds have hard seed coats that allow them to survive heat and lack of water. Asexual reproduction (cloning) of prickly pears occurs when pads (joints, segments) or fruits located on the ground take root and produce shoots. Animals and floods move broken pads long distances. These pads can survive long periods of drought before weather conditions allow them to set roots
Spread by birds and animals eating the fruit and excreting viable seed.
- Vigorous in hot, dry conditions causing other plants to lose vigour or die.
- The best form of weed control is prevention. Treat weed infestations when they are small - do not allow weeds to establish.
- Ways to prevent weed spread
- Using machinery is unsatisfactory because prickly pear pads can easily re-establish.
- Fire is an effective control method for dense prickly pear infestations. Before burning, consult Biosecurity Queensland to see if this practice is suitable for your pasture and land management practices.
- Investigations into biological control agents began in 1912. Over 150 insect species were studied throughout the world, with 52 species selected for transport to Queensland. Following intensive host specificity testing, 18 insects and one mite were released in Queensland. Eight insects and the mite remain established in Queensland. These species are:
- Cactoblastis cactorum, a stem-boring moth
- Dactylopius ceylonicus, a cochineal scale insect
- Dactylopius opuntiae, a cochineal scale insect
- Dactylopius confusus, a cochineal scale insect
- Dactylopius austrinus, a cochineal scale insect
- Chelinidea tabulata, a cell-sucking bug
- Tucumania tapiacola, a stem-boring moth
- Archlagocheirus funestus, a stem-boring beetle
- Tetranychus opuntiae, prickly pear red spider mite.
- These biological control agents continue to keep several prickly pears under control. It is important to remember not all the agents attack all prickly pears.
- Most successful of these species were the moth Cactoblastis cactorum and four cochineal mealybugs - Dactylopius ceylonicus, D. opuntiae, D. confusus and D. austrinus. The other agents are still around but not in sufficient numbers to provide control.
O. ficus-indica is not declared. O. stricta, O. aurantiaca, O. monacantha, O. tomentosa and O. streptacantha species are Class 2 declared pest plants. All other species are declared Class 1.
- A declared Class 1 species under the Land Protection (Pest and Stock Route Management) Act 2002.
- Not commonly present or established in Queensland and has the potential to cause impacts to whole or part of the State.
- Introduction, keeping, releasing and supplying (including supplying things containing reproductive material of this pest) is not possible without a permit, for special purposes, issued by Biosecurity Queensland.
- A declared Class 2 species under the Land Protection (Pest and Stock Route Management) Act 2002.
- Taking for commercial use, introduction, keeping, releasing and supplying (including supplying things containing reproductive material of this pest) is prohibited without a permit issued by Biosecurity Queensland.
- Landholders are required to control declared pests on their properties.