Quick Facts

Quick facts

• Common Prickly Pear (Opuntia stricta) is an aggressive invasive weed that can take over pastoral and agricultural lands.
• Historically, common Prickly Pear was a catastrophic weed of parts of Queensland and New South Wales until the introduction of the cactoblastis moth.
• Stem segments fragment and can be distributed by animals, vehicles and by water or wind.
• Fruits are succulent and are eaten by birds and animals and seed is distributed in their droppings.
• It can cause injury to people and animals.
• If this species is seen please notify your local weed management authority.

What Does It Look Like?

What is it?

Common Prickly Pear is an erect spreading shrub usually 0.5–1 m tall (occasionally to 2 m) and 0.5–5 m across. The stem segments at the base often thicken and form a trunk. The flattened stem segments (pads) are elliptic to egg-shaped, 10–30 cm long, 5–20 cm broad and 1–2 cm thick. They are dull green to grey-green with a whitish waxy bloom. The areoles (spots on stem segments and fruits that contain the spines and glochids) are scattered and may be spineless or bear 1–11 spines 1–6 cm long and numerous short glochids (barbed bristles). The leaves are very small and drop off.

The flowers are 5–9 cm diameter, the petaloid lobes are yellow but the outer smaller ones are often greenish to pinkish.

The almost rounded to pear-shaped fruits have scattered prominent tufts of glochids. They are succulent and purple with a white waxy bloom at maturity, 4–9 cm long and 2–4 cm in diameter. Seeds are numerous, yellow to pale brown, 4–5 mm across (Stanley & Ross 1983; Telford 1984; Anderson 2001; Harden 1990).

For further information and assistance with identification of Common Prickly Pear contact the herbarium in your state or territory.

Flower colour

Yellow

Growth form (weed type/habit)

Shrub

Where it currently grows? Preferred habitat

Common Prickly Pear is widespread, common to abundant invading mallee and acacia woodlands, open shrub lands, pastoral areas and agricultural lands and disturbed areas. It grows on plains, ranges, rocky steep slopes, beaches and off-shore islands on a great variety of soil types including heavy clays, loams, saline soils and sands (Chinnock 2007 pers. comm.).

Are there similar species?

The species that are most similar to Common Prickly Pear are Indian Fig, Velvet Tree Pear and Drooping Tree Pear.

While Common Prickly Pear is a spreading shrub to 1 or 2 meters tall, Indian Fig (Opuntia ficus-indica) and Velvet Tree Pear (Opuntia tomentosa) are generally taller shrubs or tree (usually 2–5 m tall) with larger stem segments (30 to 60 cm long), The areoles of these two species are very small and if spines are present they are very small and readily break off. The flowers of Indian Fig are large, 7–9 cm across and the red fruit have very densely clustered areoles. Common Prickly Pear flowers tend to be smaller (5–8 cm across) and the purplish-reddish fruit have scattered areoles. Velvet Tree Pear has a fine pubescence on the stem segments and fruits and has orange-red flowers (Navie 2004; Chinnock 2007 pers. comm.).

Drooping Tree Pear (Opuntia monacantha) is also a taller shrub or tree (usually 2–5 m tall) with very flattened and elongated stem segments that are deep green and shiny. Its relatively thin stem segments (usually only 4–6 mm thick) droop towards the ground during fruiting. Its flowers and fruit are similar to those of Common Prickly Pear (Navie 2004; Chinnock 2007, pers. comm.).

Why Is It A Weed?

What are its impacts?

Agriculture: Common Prickly Pear is an aggressive drought tolerant weed that is easily dispersed by fragmentation. Dense infestations can impede movement of stock, lay waste to agricultural and pastoral lands By 1926 half of the area infested with Common Prickly Pear was so densely covered that it could no longer be used for grazing or agriculture (Parsons & Cuthbertson 2001; Chinnock 2007 pers. comm.).

It can harbour pests such as rabbits. Spines and glochids can cause injury to humans and animals. The fruits are hosts to fruit fly (Parsons & Cuthbertson 2001; Land Protection 2006b).

Stock does not usually graze on common Prickly Pear due to the presence of the spines and bristles which can damage their mouths. However, in times of drought plants are eaten which may have contributed to its spread during the drought of 1902 (Parsons & Cuthbertson 2001).

Native ecosystems: Prickly Pears can dominate the vegetation of rocky outcrops displacing natives, some of which may be restricted to such outcrops, and consequently be relatively rare (GISD 2005).

How does it spread?

Common Prickly Pear readily reproduces from stem fragments, fallen flowers or immature fruits which easily break of and readily root within a few months or from seed. The succulent fruits are attractive to birds and animals (e.g. foxes) and the seeds are carried in their droppings. Plants growing adjacent to creeks and waterways can be dispersed readily downstream and much further during floods. Discarded plants and movement of plant parts during disposal has led to new outbreaks (Navie 2004).

What is its history in Australia?

The first introduction of common Prickly Pear is thought to have been by Governor Phillip at Port Jackson in 1788 along with drooping Prickly Pear and possibly a couple of other species with the intention to develop a cochineal industry for the new colony. What happened to these first introductions is no known but other introductions followed and it appears that plants were being cultivated at Parramatta before 1840 and it had spread to Chinchilla in Queensland by 1843. Segments of the plants were taken to many places for use as pot plants or hedges. By 1900 infestations covered 4 million hectares in Queensland and New South Wales but by 1920 this had exploded to 24 million hectares. Despite every control effort, estimates of the plants rate of advance were 400,000 hectares (1 million acres) per year (Parsons & Cuthbertson 2001; Land Protection 2006a).

A Prickly Pear Travelling Commission was established in 1912 and members travelled overseas to look for natural enemies and their possible use in Queensland as a biological control. By 1914 two species of Cochineal (Dactylopius spp.) and Cactoblastis Moth (Cactoblastis sp.) were introduced. The Cactoblastis larvae did not mature but work with the Cochineal was more encouraging and field trials were undertaken in 1914. Within three years of release most populations of Drooping Prickly Pear at Charters Towers, Townsville and Bowen regions were destroyed (Land Protection 2006a).

Although a number of different insects including borers, suckers and mites were trialled by the Commonwealth Prickly Pear Board in 1919, following the first world war, but these were variable in success due to their specificity to certain species of Prickly Pear (Land Protection 2006a).

Cactoblastis Moth was reinvestigated in 1924. In 1925 moths were successfully raised at Sherwood and 10 million eggs were distributed to 61 localities in affected areas during 1926–1927 and a further 2.2 billion eggs released between 1927 and 1931 (Land Protection 2006a).

The insect was spectacularly successful and by 1932 the stem boring larvae had caused the collapse and destruction of the original thick stands of Prickly Pear. By 1932, almost 7 million hectares of previously infected lands was reclaimed. The conquest of the Prickly Pear is considered the world's most successful control of pest plants by biological control (Land Protection 2006a).

How To Manage It?

Best practice management

Early control measures including digging up and burning or crushing using horses and bullocks were of limited use. Early attempts of chemical control found the most effective chemical was arsenic pentoxide but this was extremely toxic to man and animals but it continued to be used up to the early 1920s (Land Protection 2006a).

Non-chemical control: Physical removal and burning can be used to control Common Prickly Pear infestations. All dislodged segments and fruit must be destroyed to prevent reestablishment. As much of the root system as possible should be removed by grubbing or cultivation (Parsons & Cuthbertson 2001).

Biological control: Common Prickly Pear has also been recognised as a target for biological control through a cross-jurisdictional government process. This allows activities to be undertaken to develop effective biological controls. Biological control by cactoblastis insect can be used in suitable areas and is very effective for small outbreaks.

Cactoblastis control has its limitations due to the insect not thriving in dry conditions or on plants growing on poor soils, and they are not effective against all species of Prickly Pear. Today, Cactoblastis and Cochineal in addition to chemical treatments continue to be used to control outbreaks of Prickly Pear (Land Protection 2006a).

Chemical control: A number of herbicides are also effective by spraying or injecting (Parsons & Cuthbertson 2001).

Please see the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au

Does it have a biological control agent?

YES

When does it grow? (lifecycle/growth calendar)

Common Prickly Pear is most active during the warmer months and flowering occurs during spring and summer. The first flowers do not develop until the plants are at least 3 years old. The plants are long lived. However, seedlings are very delicate and usually do not survive in exposed situations. Fruits ripen at any time of the year (Parsons & Cuthbertson 2001; Chinnock 2007 pers. comm.).

Where Is It Found?

Which states and territories is it found?

NSW, NT, QLD, SA, TAS, VIC, WA

What areas within states and territories is it found?

Common Prickly Pear is extremely widespread throughout the eastern areas of Australia and it is also scattered throughout many other parts of the country. It is most abundant in central and southern Queensland and in northern New South Wales and relatively common in the rest of New South Wales. It is common in northern and western Victoria, and from the Flinders Ranges south to the Murray Region in South Australia. It also occurs in the western and south-western regions of Western Australia and in scattered locations in northern Queensland and in the southern part of the Northern Territory (Navie 2004).

Where does it originate?

Common Prickly Pear is native from the southern United States south to Mexico, Caribbean and Ecuador (Anderson 2001).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

YES

Where is it a declared weed?

NSW, NT, QLD, SA, VIC, TAS, WA

Government weed strategies and lists – Weeds Australia

Is it on the National Alert List for Environmental Weeds?

NO

Government weed strategies and lists – Weeds Australia

Is it on the Agricultural Sleeper List?

NO

Government weed strategies and lists – Weeds Australia

Names And Taxonomy

Main scientific name

Opuntia stricta

Other scientific names (synonyms)?

• Cactus opuntia var. inermis DC.
• Cactus strictus Haw.
• Opuntia bentonii Griffiths
• Opuntia dillenii (Ker Gawl.) Haw.
• Opuntia inermis (DC.) DC.
• Opuntia stricta (Haw.) Haw. var. stricta
• Opuntia vulgaris Mill. (misapplied by Bailey, F.M. 1900, The Queensland Flora. 2: 704.)

Does it have other known common name(s)?

Erect Prickly Pear, Common Pest Pear, Spiny Pest Pear, Smooth Pest Pear, Sour Prickly Pear, Australian Pest Pear, Gayndah Prickly Pear, Dillen Prickly Pear, Pipestem Prickly Pear