“The proposed application to the EPA to release gall mite will be an alternate tool to chemicals for controlling this invasive climbing and smothering pest weed.”
“The council will monitor Landcare Research updates on control outcomes of the gall mite if the application is approved by EPA.”
EPA senior advisor new organisms Clark Ehlers said old man’s beard had proven incredibly hardy.
“The vines can extend as far as 20 metres and can scramble over the ground, destroying low-growing plant communities on riverbanks, and in coastal and other sensitive habitats.”
“It colonises open forests, forest margins, shrublands, riversides, cliffs, bushtracks and hedgerows.”
Five regional councils recently estimated they spend approximately $760,000 a year to fight old man’s beard. The gall mite is minute, at about one millimetre long and has shown to be effective in significantly damaging old man’s beard plants in studies conducted overseas.
As the mite feeds, it induces growth abnormalities, or galls, on the buds and developing leaves of the host plant. The mites breed within those galls and suck out the plant’s juices, eventually killing it. The formation of galls reduces the growth rate of the weed and may cause shoots to die back. Manaaki Whenua – Landcare Research is the science provider for the application, and consulted widely before choosing six exotic Clematis species or hybrids for host range testing at the University of Belgrade in Serbia. According to the applicant, the results suggest the gall mite is expected to effectively colonise only old man’s beard in New Zealand.
Occasional galls may be expected on exotic, non-target Clematis species, but the presence of low numbers of mites is unlikely to cause them damage. The application says that old man’s beard causes environmental damage throughout most of New Zealand, often in distant or inaccessible areas of high conservation value.
Biological control by the gall mite could provide a safe and sustainable alternative to mechanical and chemical methods of control, the applicant says.
The gall mite could also disperse to isolated infestations that are inaccessible, or unknown to land owners. It would persist from year to year.
Successful biological control of the weed would mean reduced costs for regional councils, DoC and other land owners. Public submissions on this application close at 5pm on August 29.
