Skip to page content
You are here: Home > Stories > Why are weeds bad?

Why are weeds bad?

Students in Auckland, the East Cape and Westland are waging war against weeds to help protect our native plants and the wildlife that rely on them.

examining weeds

Students, teachers and local communities have teamed up with Landcare Research and Lincoln University to record what weeds are growing in their area and find out what insects might help to control these weeds.

Weeds may seem harmless and some are even quite pretty, but these foreign plants are slowly killing our native ones because they compete for nutrients, water, sunshine and space – forcing native plants to try and survive elsewhere.

Most of our native animals rely on native plants and many of these plants, like kawakawa and mānuka, have medicinal properties and other uses that directly benefit us.

“Because of New Zealand’s isolation, eighty percent of our native plant species are unique and found nowhere else, but some are now endangered because of the impact of weeds,” says Murray Dawson at Landcare Research.

labelling weeds

The weeds that are taking over native plants’ living spaces are very difficult to rein in, to the point where even the experts need more help.

“The people whose jobs are to help control pest plants desperately need more community support,” Murray tells us.

“They need lots of trained eyes and boots on the ground to help discover infestations in enough time so that they can be managed quickly”.

Scoping out the enemy

This is what motivated Murray to set up a weed-recording project tied in with NatureWatchNZ, a community-based citizen science and environmental monitoring website, so that all New Zealanders can help win this war against weeds.

Murray and a team of scientists and educators spent a day at each of the nine schools they visited. The team took the students out to various spots close to the school grounds to check out what plants were growing there.

The students photographed the plants, recorded where they were found and then identified the weeds using smartphone and tablet apps.

The students then uploaded their findings to NatureWatchNZ, where online experts helped to confirm whether they had correctly identified their submitted plants as weeds.

“I was amazed by how quickly the kids got to grips with the plant identification tools, which are the same ones that professional researchers use!” Murray says. “The children were really excited by the work we were doing and it didn’t take them very long to learn how to identify and record the weeds.”

identifying weeds with app

Seeing the effects

Monique Russell at Tread Lightly Caravan was the project’s educator at Te Kura Kaupapa Māori o Kawakawa Mai Tawhiti in the East Cape and two other schools in Auckland.

Monique and student

“One of the highlights for me was seeing the kids in the East Cape realise how much their community’s economy could be affected by invasive weeds,” she says.

“There’s a lot of mānuka honey farming in the region and the mānuka trees have the potential to be threatened by invasive weeds. The school and kids now want to keep the weed project going, because it has real relevance to them.”

Students in most areas found cotoneasters growing near their school and Murray tells us this is one of the worst weeds in New Zealand because it is also a common garden plant.

“Cotoneasters are a real pest,” he explains. “These are still being grown in school grounds and in people’s gardens because they are hardy, have white flowers and attractive red berries. Unfortunately, birds love to eat these berries and spread them everywhere.

“These plants can tolerate shade, so they are one of those nasties that can grow and compete with native bush. At Kaniere School we found them practically dominating a hillside.”

Students collecting gorse

Exploring weed-eating bugs

Each school nominated one student to visit Landcare Research’s headquarters in Lincoln.

Here, the students found out about preserving plant samples by pressing and labelling them, scanning the pressed leaves and flowers for a high-resolution image library, and learnt where the samples are filed in the herbarium – a physical plant library – for future reference.

The students also looked across all the schools’ uploads on NatureWatchNZ to spot trends and found out which insects can be used to control certain weeds.

“I had the best time and learnt so much,” says Charlotte, a Year 6 student at Haast School.

“We studied bugs and learnt about which bugs eat which plants. We did an experiment where we had three kinds of plants – strawberry, hops and thistle – that we added caterpillars to and waited an hour for the caterpillars to eat the leaves. We found out that the caterpillars preferred thistles.”

“I found this trip very interesting and inspiring,” says Lois, a Year 11 student at Mt Albert Grammar. “I think that my favourite activity was the caterpillar experiment.”

girl holding weed   feeding experiment   child holding weed

Read more about the project on Landcare Research's website


About the project

Landcare Research LogoLincoln University logo

Winning the War against Weeds is supported by the Unlocking Curious Minds contestable fund.



Unlocking Curious Minds

Unlocking Curious Minds supports projects that excite and engage New Zealanders who have fewer opportunities to experience and connect with science and technology.

Find out more

View all stories