29 Feb New effort to beat noxious vine
Monday February 29, 2016 Written by Cameron Scott Published in Local
A second attempt is to be made to introduce a bio control agent to curb mile a minute vine, which is swallowing bush and plantations at a rapid rate all over Rarotonga.
Bringing the invasive vine under control is one of the aims of a $1 million weed control project funded by the New Zealand Ministry of Foreign Affairs and Trade, Landcare Research New Zealand and the Cook Islands Ministry of Agriculture.
The first attempt to establish Puccinia spegazzinii rust-infected mile a minute plants in April last year failed after the plants, housed at the Ministry of Agriculture in Arorangi, were fatally damaged by heavy rain and strong winds.
Landcare Research research leader Quentin Paynter, who travelled to Rarotonga with colleague Chantal Probst to attend a function marking the arrival of the plants, yesterday described the first attempt as “a bit of a disaster.”
He said Probst had managed to successfully transfer spores to potted plants in the Ministry of Agriculture shade house, and they had shown signs of successful infection.
“Unfortunately, heavy rain and strong winds for more than three days damaged the plants soon after inoculation and most of the leaves – including the infected ones – dropped or damped off, so the Puccinia spegazzinii culture died out.
“This all coincided with Maja Poeschko becoming ill with chikungunya, which didn’t help.
“Chantal recently inoculated a fresh batch of plants with Puccinia spegazzinii in our containment facility in Auckland and she is due to bring a second shipment of the rust to Rarotonga, arriving on March 8.
“We are confident that once we get it established, the rust fungus will soon spread throughout the island, but getting biocontrol agents established from small founder
populations is always a tricky stage in a biocontrol programme.”
If the second attempt to introduce a control is successful, the first signs of mile a minute vine diminishing on Rarotonga through the release of plants infected with the South American-sourced rust fungus could appear in as little as two years.
However the rust fungus will not eliminate the pest vine completely, meaning there will be ample supplies for island residents who use it for its healing properties.
Paynter says Landcare Research has also gained approval to release a scale insect Tectococcus ovatus to control strawberry guava – Psidium cattleianum – in Rarotonga.
“I’m aiming to come out to release it in April or May.
“We also have completed host-range testing a butterfly (Heliconius erato cyrbia) that feeds on red passionvine and confirmed that it is highly host-specific and an application to release it in Rarotonga has been submitted to the National Environment Service.”