Manawatu stream excavated to eliminate one of world's worst weeds

A stream in the Manawatu is being excavated to uproot the invasive alligator weed before it wreaks havoc on farmland, the river and wetlands.

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Alligator weed has already damaged farms and the environment further north, but was only discovered in Manawatu last year. Source: 1 NEWS

Regarded as one of the worst weeds in the world, alligator weed arrived in New Zealand in the early 1900s but it wasn't discovered in the Manwautu until last year.

As its name suggests, it's an aggressive weed that chokes waterways, takes over vegetation and can be toxic to livestock.

It's taken hold in waterways around the Waikato, where keeping it under control with herbicides is a full time job.

The Manawatu-Whangnui regional council is not taking any chances and is digging out a lot of dirt to get the weed's roots.

"This is the whole thing about alligator weed in the Manawtu, it's the needle in the haystack," said Craig Davey, an environmental co-ordinator with the council.

The weed has been detected in 70 locations across 10 kilometres of the Mangaone stream in Palmerston North.

The council is trying to stop it in its tracks before it gets into the Manawatu River. "The damage is immense. We've got 70 kiolmetres of Manwatu River from Palmerston to the sea. At the sea end, we've got the Ramsar wetlands. Alligator weed would smother wading bird habitat, nest areas," Davey said.