Environment Waikato’s Biosecurity Committee wants infestations of alligator weed in the north Waikato to be hit harder as new sites emerge.
This week’s Committee meeting heard that extensive monitoring had found new sites of the invasive aquatic weed, but there were difficulties controlling it under the current resource consent conditions.
The increased volume and distance that it had been found growing meant the current consent needed to be reassessed and more suitable control options found. Spraying of the weed within the Lower Waikato River control area was undertaken and sites revisited during the summer. Chemical spraying had only killed about nine out of every 10 plants.
The weed was growing on the lake margins of Lake Whangape and a large infestation was identified at the Ohinewai boat ramp.
The idea situation was to spray plants in early spring but problems with timing and habitat had been encountered. The current consent did not cover all areas of infestation and allowed for the use of one air boat, which meant frequent visits were required to keep the plants under a “holding pattern”. Only the growth was being killed, rather than the actual plants.
While a variation to the current consent was not the best option, a new consent could be applied for to allow the discharge of herbicide.