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Quick action controls Alligator weed outbreak
Apr 20, 2005

Environment Bay of Plenty staff are confident they have “knocked on the head” a potentially devastating aquatic weed found in the eastern Bay of Plenty in February – but they’re not taking any chances.

Staff moved quickly into action after discovering alligator weed, a serious problem in United States waterways, growing along the banks of two canals that flow into the Tarawera River.

Pest plant coordinator John Mather says they located about 40 clumps of weed, with an average size of one square metre. The clumps were sprayed under low pressure with a herbicide that does not damage aquatic life.

“We are very fortunate to have discovered the alligator weed at such an early stage, before it really got established or moved off the river bank and into farmland. It would have been much harder to control then.”

Mr Mather is satisfied with the results of the spraying programme. “We seem to have achieved a good level of control but will monitor it carefully over the next two or three years to make sure.”

He suspects the weed established in a nearby grazing property, which hosted an infestation more than a decade ago. At the time, it was suspected the weed was brought into the area on contaminated farm machinery.

A native of South America, alligator weed is already widespread in Northland and has been discovered in Auckland and the Waikato. The Bay of Plenty hosts a handful of land-based sites, all of which are under intensive long-term control programmes.