A group of teenagers leading Northland's battle against an invasive weed are about to take their campaign against the smothering plant pest to the world.
The Tradescantia Terminators — a group of Kerikeri High School students who have already won accolades for their work ridding a bush walkway of tradescantia, also known as wandering jew or wandering willy — have been selected to represent New Zealand at the 2019 International Future Problem Solving Competition in Boston, United States.
The seven-strong team is also planning public workshops to share what it has learnt about using biological warfare to combat the weed, which chokes gardens and kills forests by smothering native seedlings.
The project started two years ago when they noticed bush beside the new Wairoa Stream track was carpeted in weeds. Tradescantia spreads so easily weeding won't get rid of it and spraying wasn't an option due to the proximity of the stream, so they looked into biological control instead.
They found a tiny, shiny beetle that eats only tradescantia and comes from Brazil, like the weed, had recently been introduced to New Zealand. With advice from the Northland Regional Council they found a population of the bugs in central Kerikeri, made contraptions called ''pooters'' to catch them, then released them near the stream.
Within nine months they found tradescantia cover had dropped from 100 to 59 per cent at one site and 100 to 46 per cent at another. The weed's thickness had also fallen from 59 to 22cm and 29 to 8cm. The students were confident cover would drop to 30 per cent this summer, enough to give native seedlings a chance of survival.
The Tradescantia Terminators were one of six teams invited to compete in Auckland on November 2-4, where they had to make a display, give a presentation and be interviewed by a panel of judges. They won the senior community problem-solving division, earning the right to compete at the world finals next year.
Jeany Kim, 15, said at first they only aimed to reduce the weed along Wairoa Stream. However, as more and more people got in touch asking for help tackling tradescantia, the time required to collect the beetles made it unsustainable.
Emilie Jones, 14, said that prompted the group to change its goal to informing people about tradescantia and teaching them how to control it.
Charlie Potter, 15, said their project had the potential to make a difference not just in Kerikeri, but nationally and internationally.
Florida, Queensland and South Africa had similar problems with tradescantia but New Zealand was the only place attempting biological control.
The students will now start planning how to raise the $7000 they each need to get to the USA.
The full team is Charlie Potter, Charlotte Gamble, Emilia Finer, Emilie Jones, Faith Hohepa, Jeany Kim and Wilson Hookway. All are in Year 11 except Emilia, who is Year 10.
■ The students will hold public workshops on December 2 and February 9, starting at 2pm, to demonstrate how to make pooters and catch and release the beetles. Email firstname.lastname@example.org with name, contact number and choice of date to book a place. The Far North District Council will cover the cost of materials.