Mechanical control of alien spiny cactus pears (Opuntia ficus-indica and O. engelmannii) and its utilisation as processed animal feed

Seafarers introduced spiny cactus pears more than 250 years ago at the Cape of Good Hope. Settlers transported the cacti inland and by the 1950s, about 1 million hectares had been invaded by alien spiny cacti in South Africa. Some regions, especially the Eastern Cape Province have dense, impenetrable thickets of invasive cacti. Invasive alien plants (IAP) pose a threat to South Africa’s biological diversity, water security, the ecological functioning of natural systems, and productive use of land. In 1914, 22 spineless cactus pear cultivars from the Burbank collection in California were introduced in South Africa, primarily as animal feed, and since then, major advances have been made in utilising spineless cactus pears (Opuntia ficus-indica and O. robusta) as multi-use crops for human and animal consumption. In addition to conventional use of fruits, the cladodes and fruits are processed and used as animal feed. In a new initiative, the construction footprint of a wind turbine facility in the Eastern Cape had to be cleared of spiny cacti, notably the spiny form of O. ficus-indica and the spiny O. engelmannii. A range of methods are used in South Africa to control IAP’s, namely mechanical, chemical, biological, and integrated control methods. This initiative is focussing on mechanical control of invasive alien cacti and utilising it as processed animal feed. It is easy to manually harvest and process spiny cactus pears, but this requires physical strength, perseverance, and protective clothing for workers. This initiative comprises three successive stages, namely harvesting spiny cactus pear plants, cutting it in strips, drying cladodes in the sun, and grinding it in a hammer mill. The long spines of cacti are degraded mechanically by grinding the sun-dried cladode strips in a hammer mill before using it as animal feed and is safe for consumption.