Forest and Bird are concerned that The Minister for Primary Industries - the government agency in charge of biosecurity - is promoting pest weed species as part of its Billion Trees programme, including one species that is illegal to sell or propagate and others that ratepayers are spending millions trying to eradicate. They say the list could cost taxpayers millions more - and undo countless hours of volunteer work that have been dedicated to trying to get rid of these weeds, such as the Japanese Spindle Tree

Kevin Hackwell is the Chief Conservation Advisor for Forest and Bird. Stewart spoke with him and wanted to know how serious is the problem and how on earth was this even allowed to happen in the first place?