Tiger Pear (Opuntia aurantiaca) is a weed of national significance. A cactus native to South America, it was brought to New South Wales in the late 1800’s. By 1911 the Tiger Pear was recognised as serious threat in New South Wales. Within Victoria the plant is confined to three sites with the largest infestation occurring along Little River in Melbourne's Western Plains district.
Tiger Pear typically grows in dry harsh environments including pastoral areas and rocky crevices. Although the plant does not establish in wet riparian zones, its dispersal is mainly attributed to fluvial processes and animals. Segments readily establish wherever they lodge and once established form an impenetrable groundcover.
Melbourne Water commenced controlling Tiger Pear at Little River in 2008. The treatment methods to date have combined herbicide application with manual removal. Despite a targeted program over 5 years Tiger Pear has not yet been adequately controlled. Melbourne Water is investigating alternative control methods to improve cost effectiveness and reduce environmental damage.
One such trial method is the use of a propane fuelled flame torch. The trial will examine if incineration of Tiger Pear eradicates the cactus completely, thereby eliminating the need for herbicide application. By ensuring Tiger Pear is eradicated on its initial treatment, the knock on effect is lower maintenance costs and an overall reduction in capital investment in one area. Short term results indicate incineration to be a far more effective method in eradicating tiger pear along waterways than herbicide application.
Expected benefits in using the incineration method at Little River include;
Targeted application limiting off-target damage to both indigenous plants and Growling Grass Frog known to occur in the area (Vulnerable under EPBC Act 1999),
Identifying and treating the complete extent of the plant when hidden within grasslands and below dense shrub,
Incinerating all spines removes the health hazard to crews and removes the barbs that attach to animals,
Reducing or removing the use of concentrated herbicide,
Reducing capital expenditure, and
Providing a winter management options not previously feasible through herbicide application.