Opuntia subulata

Controlling an invasive species demands a well-planned management, which includes the determination of the invaded area, identifying the causes of invasion, assessing the impacts, defining the intervention priorities, selecting the adequate control methodologies and their application. Afterwards it is fundamental to monitor the efficiency of the methodologies and recuperation of the intervened area as to perform, whenever necessary, the follow-up control.

The first measures to be taken should be preventive, ceasing to use this species and replacing it, whenever possible and appropriate, with native species. It is also important to bet on the good state of conservation of the habitats, with their communities of native plants, as this makes the establishment of this and other invasive plants difficult.

The control methodologies used for Opuntia subulata include:

Physical control

Hand and mechanical pulling preceded or not by cutting the stems: in more compacted substrates, the pulling should be carried out in the rainy season in order to facilitate the removal of the root system. It must be ensured that there are no fragments of the plant left in the soil, which could easily root and create new foci of invasion. All uprooted/cut material must be carefully removed from site (do not leave fragments as they can give rise to new plants) for later destruction and burning. Never join with other plant residues as it migh survive and spread.

Cutting individual plants or small nuclei, followed by careful destruction (e.g., cutting into pieces and burning on site, or bagging and depositing in a safe place where they cannot take root) can work..

Chemical control

Bearing in mind the potential negative effects of chemicals on other species and on the environment, always consider their application and 1) use it only in situations where physical control or other methods do not constitute a reasonable alternative; 2) strictly follow the safety and application instruction label and use solely products approved for the species and the specific case; 3) apply as limited as possible to target species.
Chemical control should be done through the application of herbicide, through injection (active ingredient: glyphosate) in the stems. It must be carried out before fruit development, since the seeds of the still green fruits are already viable.

Biological control

In South Africa, Cactoblastis cactorum (Bergroth) (Lepidoptera: Pyralidae) has been used, which feeds inside cladodes but whose results seem to indicate that it is not effective.

This agent has not yet been tested in Portugal, in order to verify its safety in relation to native species, so its use is not yet an alternative in our country.

The best control results have been achieved when integrated management strategies are incorporated, including herbicides, mechanical and physical methods.