Pest plant - Prickly pear

Prickly pears (Opuntia species) are succulent perennials that invade rangeland and native vegetation in the drier parts of South Australia. Wheel cactus (Opuntia robusta) and common prickly pear (Opuntia stricta) are the most prominent species.

The hybrid cultivars grown for fruit production under the name of Opuntia ficus-indica are not declared in South Australia.

The various species of chollas, Hudson pears and rope cactus (Cylindropuntia and Austrocylindropuntia species) are not considered in this information.

Description

The appearance of these cacti can vary significantly, from the more familiar tall, erect and flat segmented common prickly pear through to small shrubs with narrow flattened, rope like segments such as Hudson pear.

Why is it a problem?

• can become weeds in pastoral land and open native vegetation
• in these habitats, species such as wheel cactus can displace desirable vegetation
• forms dense infestations that limit access by stock, humans and vehicles.

Distribution

Wheel cactus

• Flinders Ranges and the adjoining North East Pastoral districts – major infestations
• Peterborough and mid Murray area – major infestations on permanent grazing lands.

Prickly pear

• Flinders Ranges and Riverland regions – infestations
• Adelaide area, along the highway from Adelaide to Port Augusta, Murray Bridge, Goolwa and Reevesby Island – spot infestations.

Opuntia aurantiaca, O. Elatior, O. Engelmannii, O. Microdasys, O. Monacantha, O. Puberula, O. Tomentosa and several other species

• Individual plants and small patches close to gardens and former settlements wherever they have been planted in the agricultural and pastoral zones of South Australia.

Ecology

• perennial plants that are generally long lived
• flowering typically occurs from spring to summer with fruits forming in late summer through to early autumn
• not all species develop fruit but those that do produce numerous seeds.

How it spreads

• mainly established as a weed close to localities where they were formerly planted
• vegetative spread is the most common
• fruit is eaten by birds and some mammals, dispersing seed over wider areas
• via dumped garden waste and runoff water.

Related links

• Pest plants (web page)