Great willowherb found

Pegasus lake has achieved an unfortunate first for New Zealand after the invasive weed great willowherb was discovered growing there.

Biosecurity New Zealand (MPI) confirmed that the invasive weed, latin name Epilobium hirsutum, has been found growing in several areas in Canterbury.

It had not previously been recorded as present in New Zealand.

Initial discoveries occurred in and around the lake at Pegasus township, and near the Kate Valley landfill, located approximately 40 kilometres north of Lake Pegasus.

A field team is currently searching all likely places in the wider area to determine the extent of the incursion. To date, great willowherb has been positively identified at five sites.

Great willowherb is characterised by its aggressive growth, and there is concern it may crowd out native wetland plants. It can form dense stands, impeding water flow in waterways and wetlands. It may also spread to undisturbed damp areas and invade existing vegetation.

At present there is no risk to fresh water fish or agriculture.

Biosecurity New Zealand team manager response John Brightwell said that once the extent of the problem was understood, officials would be in a better position to determine what response actions can be carried out.

‘‘We’re in the early stages of determining the severity of this incursion,’’ he said. ‘‘Once we’ve determined this, we’ll work closely with Environment Canterbury and the Department of Conservation to develop an appropriate response.’’

In the meantime, Biosecurity New Zealand is urging all Cantabrians to be on the lookout for great willowherb, take a photo and to report it to Biosecurity New Zealand’s pest and diseases hotline, 0800 80 99 66.