Why biocontrol

Once established, biocontrol is inexpensive compared to other control methods

Unlike herbicides, which need  to be reapplied regularly to control weeds, a well-established biocontrol agent  can do its job with little input from people.   Successful biological control for mist  flower, St. John’s wort, and ragwort means that it is rare for other  control methods to be required for these weeds. So in the long term, biocontrol  can be very cheap.

Some weeds can’t be controlled by conventional  methods

Some weeds are difficult to  kill with herbicides, and quickly resprout from roots or seeds after herbicide  application. Other weeds are so widespread or found in such inaccessible areas  that using herbicides is not economically feasible. Biocontrol agents can  penetrate even the most inaccessible and widespread weed populations, and they  keep coming back as the weed resprouts.

Biocontrol can be more environmentally friendly  than conventional methods

Some weeds invade sensitive  or rare native habitats, where herbicides would kill important native flora and  fauna. Biocontrol agents eat only weeds, leaving desirable plants untouched,  and they don’t pollute the soil or waterways.

Heather: The making of a weed

History of heather in New Zealand. Originally sowed and planted by John Cullen in Tongario National Park as a habitat for gamebirds. Grouse was introduced but did not survive in New Zealand. However heather has established and is a major problem in the park, forming dense mats, displacing natural vegetation and the homes of native invertebrates and lizards. For nearly 100 years efforts have been made to eradicate heather without much success.