Invasive neem trees threaten Mataranka’s environment so these Northern Territory locals … – ABC

Margo Sullivan feels lucky to call Mataranka home.

The small outback community in the Northern Territory, about 400 kilometres southeast of Darwin, attracts thousands of visitors each year and is famous for its thermal springs.

“It's somewhere people can come, relax and be surrounded by Australian nature, rather than the sounds of cities,” Ms Sullivan said.

For most of her life, the young pastoralist has lived on a small cattle station on the outskirts of town, along the banks of the Waterhouse River.

Now she feels the “pristine” natural beauty of the region could be lost if a rapidly spreading weed isn't controlled.

“You can see the neem trees starting to take over … they grow thick, choking out much native vegetation.”

portrait of a young woman wearing a pink work shirt and brown cap with trees in the background
Margo Sullivan said neem trees and other weeds were sometimes overlooked by government.(ABC Rural: Max Rowley)

An invasive weed takes hold.

Neem trees are widely spread across northern Australia after being deliberately introduced as a shady ornamental tree used to produce an insecticide.

But in 2014, the trees were declared a class B weed in the Northern Territory.

That means the weed must be controlled, but there is no plan for eradication.

Doris Baylis, from Mataranka Station, is the Roper River Landcare Group secretary.

“I don't know that people realise how invasive it is,” she said.

“Once you get closer to the river, you start seeing monocultures – all you see are neems.”

The pastoral Landcare group comprises property owners, land managers and residents and has won a national Landcare award for making Mataranka “neem-free in 2023”.

a group of people helping pour herbicide into a sprayer.
The Roper River Landcare Group is trying to eradicate neem trees from Mataranka.(Supplied: Roper River Landcare Group)

“In the community, we shouldn't have any problems … it's your river corridors where it's going to be much harder to get rid of [neem trees],” Ms Baylis said.

“But if [landholders] make an effort to get rid of neems on their properties, it is possible and we're doing it step by step.

“We do have to take control at some stage … if we don't, we will end up with a much broader landscape of neem trees instead of a landscape that the Northern Territory is proud to say is pristine.”

a woman in a pink shirt holding a hand spray unit surrounded by neem trees.
Doris Baylis sprays neem trees around Mataranka.(ABC Rural: Max Rowley)

Below the Berrimah line

Margo Sullivan said neem trees and other weeds like bellyache bush were sometimes overlooked by the government.

“It does feel like sometimes if it's not impacting the greater Darwin region, it's not something the government's too interested in looking at,” she said.

“A lot of these weeds get thrown in the too-hard basket.”

The NT government currently funds the Gamba Army's efforts to tackle gamba grass, mostly in Darwin's urban and rural areas. The federal government has also committed almost $10 million to fight the highly invasive weed.

Close up of a hand holding the long dark green leaves of a neem tree.
Neem trees were deliberately introduced to the NT as a shady ornamental trees.(ABC Rural: Max Rowley)

Ms Sullivan said it was difficult for landholders to manage weeds with limited time and resources. Still, the Landcare group was working to support and educate locals about the impact of neem trees.

“It's a big ask for someone to outlay a lot of money, getting rid of a weed that probably doesn't affect their production so much – but it is impacting the environment,” she said.

“[But] you need everyone on board because you only need one person not to engage with getting rid of neems, and their block acts as a seeding block for everyone else's – and you end up with a continuous battle, and you're never able to get rid of the source.

“If the same effort were put into resources for neems and some other weeds as it is for gamba grass, you'd start to make a difference.”

A man wearing protective clothing spraying a thicket of neem trees surrounding a native gum tree. 
A single mature neem tree can produce up to 50,000 seeds per year.(ABC Rural: Max Rowley)

Fears of further spread

Local tourism operator and Landcare member Des Barritt said neem trees would spread hundreds of kilometres along the river to communities in south-east Arnhem Land without further control.

“If you had a magic wand and the government had a heap of money, [the river corridor] is where you would be focusing efforts,” Mr Barritt said.

“But [the Landcare group] doesn't have the resources for that … and the government will never have the money to do it.

“We're just doing what we can do.”

A man stands with his arms folded in a shed doorway wearing an old wide-brimmed hat, blue singlet and jeans.
Des Barritt's livelihood depends on the pristine rivers and waterways in the Mataranka area. (ABC Katherine: Roxanne Fitzgerald)

Ms Sullivan has already seen how neem trees have spread along the Waterhouse River.

“We're starting to find neems in areas we hadn't seen before,” she said.

“They're working their way further and further up the river.”

She said if the weed weren't controlled, future generations would be left with a “sea of neems”.

“They'll never get to see the rivers and the springs and all the native vegetation as it should be in all its glory,” Ms Sullivan said.

“All the pristine Australian landscapes that are so stereotypical of this area, they won't exist anymore, and that'd be sad.”


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