Biosecurity New Zealand is to tighten surveillance of genetically modified crop trials.
A trial carried out by the Institute of Plant and Food Research at Lincoln near Christchurch was ended after it was found one of the GM kale plants had been allowed to regrow and flower outside.
Biosecurity New Zealand says the chance of cross pollination through either wind or bees is very low.
Principal adviser Doug Lush says the investigation did show a series of worrying lapses in the conduct of the plant and food trial.
As a consequence, he says the audit for any future trials at the site will be significantly tightened.