CONTROL OF WILD KIWIFRUIT (ACTINIDIA SPECIES) IN BAY OF PLENTY, NEW ZEALAND

A large population of wild kiwifruit, mostly Actinidia deliciosa, has grown in the Bay of Plenty region of New Zealand over the past 30 years, fueled by the increasing commercial success of kiwifruit production. This fast-growing non-native woody vine has invaded native forest and scrub and commercial Pinus radiata plantations. The environmental impacts of wild Actinidia have led it to be listed as a Total Control Pest Plant in the Environment Bay of Plenty Regional Pest Management Strategy. Wild vines can be reliably killed with any of sprayed Tordon® Brushkiller (picloram/triclopyr), Grazon® (triclopyr) and stump treatment with Vigilant™ gel (picloram). $NZ523,000 was spent from 1998 to 2005 on controlling wild Actinidia in the Bay of Plenty, funded by partnerships between the kiwifruit industry and Environment Bay of Plenty. The four control seasons of 2001/2002 through to 2004/2005 more than 21,000 vines have been killed. Similar control efforts each season have found progressively fewer vines (almost 6000 fewer vines in 2004/2005 than 2001/2002), indicating that the population is being successfully reduced. Between 67% and 96% of the pre-control population of established wild vines are estimated to have been removed. Sustained control over several more years will be required to reduce this population to an easily manageable size. This is complicated by continued recruitment into the wild population from commercial crops, principally via birds feeding on reject kiwifruit fed out to farm stock. We suggest that other countries that commercially propagate wild kiwifruit outside of its native range take care to prevent wild populations from establishing in surrounding vegetation.