Tutsan Agents Released
An excited group of Taumarunui farmers gathered at a field day in February to make the first releases of two biocontrol agents that will hopefully, over time, be able to rein in tutsan (Hypericum androsaemum).
Although the weed is widespread throughout New Zealand, it was the Tutsan Action Group (TAG), which formed a decade ago from a highly concerned community, that succeeded in raising the funding to research biocontrol options for this weed. A spokesperson for the group, Geoff Burton, a farm business management consultant, said there was a great deal of optimism that the biocontrol agents would offer some hope of controlling tutsan, because manual and chemical control options had been exhausted. “In its early stages, individual plants can be easily controlled by pulling or spraying, but more mature infestations have a robust root system and are much more difficult to control,” said Geoff. “Because of the rough terrain in the King Country and the difficulties associated with access, it is not practical to attempt control either manually or using chemicals,” Geoff said. “Stock won’t touch it – not even goats!” he added.
The TAG includes not only farmers, but also representatives from the Horizons Regional Council, the Department of Conservation and Landcare Research. Hugh Gourlay has been involved with the project from its inception. Hugh said that it was very satisfying to finally be releasing the agents, which had undergone extensive testing before being approved for release in New Zealand by the Environmental Protection Authority.
“Literature searches showed that tutsan originated from the Caucasus, so we travelled to Georgia, Europe, to see if we could find any potential biocontrol agents attacking tutsan there. Here we encountered two insects attacking tutsan that are not found anywhere else in Europe,” said Hugh. A moth (Lathronympha strigana), which primarily feeds on the seeds but also on tutsan leaf tips and inside stems, and a leaf-feeding beetle (Chrysolina abchasica) were tested and found to be sufficiently host specific and not a risk to native plant species. “We have already been able to release the moth at 30 sites around the central North Island, but the beetle is more difficult to rear in captivity, so only one release of them has been made so far,” said Hugh.
“The weed has reduced the amount of land available for grazing, and as a result this has had a negative impact on the value of properties in the King Country,” Hugh added. An economic analysis completed by Geoff Burton in 2013 found that tutsan was costing some landowners up to $400 per hectare per year to control, and an overall total of $2.3 million per year in direct and indirect costs. In addition, a reduction in land value of $32 million was attributable to tutsan.
Members of the TAG have themselves made a big financial investment in getting the agents to the release stage, raising more than $1.3 million from within the farming community, which helped to leverage funding for the project from the Ministry for Primary Industries’ Sustainable Farming Fund (SFF). A majority of the members have voluntarily given their time to the project. This project has the largest number of financial contributors of any SFF project, with around 300 farmers making some form of financial commitment to the project over the past 10 years.
The secretary of the TAG, Ros Burton, was at the field day and said that the participants were very interested in the science behind the project and genuinely engaged with the concept of biocontrol and what it could offer in terms of weed control in the region. Ros said that at first she found applying for large sums of money quite daunting, but that the process has since been streamlined and she now found the tasks of developing budgets, milestones and reporting much easier. Ros added that it was important for action groups to remain focused, to meet regularly so that members are well informed, and to draw on the advice of similar action groups involved in weed control.
In the meantime the TAG will continue to meet to discuss the progress of the two agents and what can be done to support research into rearing the beetle in containment so that further releases can be made. The chairman of the TAG, Graham Wheeler, has since sold the farm that he owned in Taumarunui, where the agents were released, but he intends to continue his involvement with the group, such is his commitment to reducing the incidence of this weed in New Zealand.