Blackberry Biological Control RnD4Profit-14-01-040

Summary

​European blackberry (Rubus fruticosus agg.) is an important invader of southern Australia pastures and natural ecosystems. The goal of this project was to explore new avenues for blackberry biocontrol. The project primarily focused on determining if the blackberry decline syndrome, observed in south-west Western Australia over the last 10 years, could be manipulated and developed as an effective and safe biocontrol tool. Results from glasshouse experiments revealed that Phytophthora pseudocryptogea, but not Phytophthora bilorbang, could kill or adversely affect different species of blackberry, when plants were exposed to fortnightly 72-h simulated flooding treatments. In host-specificity tests, P. pseudocryptogea did not significantly affect pasture species, but killed or considerably reduced growth of several native species, including many in the Acacia and Eucalyptus genera. These results were the basis for the decision not to proceed with field trials. Since Phytophthora species were found not to be a viable option for blackberry biocontrol, the project undertook a preliminary investigation into the field host-range of the stem-boring sawfly, Phylloecus faunus (=Hartigia albomaculata), identified in the 1970s in Europe as a potential biocontrol agent for blackberry. Field surveys conducted in mainland western Europe and the UK only found P. faunus on Rubus ulmifolius, which belongs to R. fruticosus agg., and not on the closely-related species Rosa canina, at sites where the two species were sympatric. A range of possible options as the next steps towards blackberry biocontrol in Australia are presented in this report.