Project reference: 2000-04
Biological Control of Blackberry
Project description:
Of the brush weeds, blackberry (Rubus fruticosus agg.) is second in New Zealand only to gorse, in terms of the volume of herbicide sold for its control. The weed competes with plantation trees (of both major and minor forest species) and interferes with silvicultural activities. A successful biological control programme against blackberry would significantly decrease financial and environmental costs associated with this weed and its control.
In the late 1970s Australia initiated a biological control programme for blackberry based on the European blackberry rust, Phragmidium violaceum. In Australia and New Zealand blackberry is an aggregate of numerous species and hybrids that differ in their susceptibility to different strains of P. violaceum. Host range studies were conducted in Europe to select the most virulent strain of P. violaceum for Australia´s worst blackberry species. Before this testing was complete an unknown strain (or strains) of the rust was illegally introduced to Australia. The illegally introduced strain was first detected in 1984 while the officially sanctioned, virulent strain (F 15), was released in Australia in 1991 B 1992.
Phragmidium violaceum was first recorded on blackberry in New Zealand in 1990. It is believed that spores of the illegally introduced rust strain(s) arrived from Australia via wind dispersal across the Tasman Sea. Since then, P. violaceum has spread over most of New Zealand, but disease incidence has been sporadic and uneven. In particular, there have been very few recordings of P. violaceum from areas where R. cissburiensis and R. cissburiensis hybrids predominate. There may be potential for greatly improved biocontrol in New Zealand by introducing rust strains with greater virulence against these (and other) blackberry species. It is not known if the F 15 strain has also spread to New Zealand.
Australian Researchers at the Cooperative Research Centre for Weed Management Systems have started a programme to characterise genetically the P. violaceum strains present in Australia. Through a collaborative relationship with the CRC, Landcare Research has a unique opportunity to have the rust strains present in New Zealand similarly characterised and compared with the Australian strains. This opportunity is of very limited duration as the current CRC is expected to wind up in mid 2002.
We propose to collect blackberry rust from a number of sites across New Zealand, extract rust DNA, and send it to Australia for genetic analysis. Results can be used to determine the potential for improving blackberry biocontrol by importing additional strains of P. violaceum from Australia or Europe. The Bay of Plenty Regional Council have pledged $6,000 per year ($12,000 total) towards this project.
Research Provider:
Landcare Research
