The effect of Phragmidium violaceum (Shultz) Winter (Uredinales) on Rubus fruticosus L. agg. in south-eastern Victoria

F.A. Mahr and E. Bruzzese, Keith Turnbull Research Institute and CRC for Weed Management Systems, Agriculture Victoria, Department of Natural Resources and Environment, PO Box 48, Frankston, Victoria 3199, Australia.


Summary

The introduced blackberry rust fungus, Phragmidium violaceum, was first recorded in Australia in 1984 on Rubus ulmifolius hybrid at Foster, south-east Victoria. This strain was believed to be introduced illegally and although its spread across Australia was rapid, its virulence to the most widespread species of blackberry naturalized in Australia was low. Releases of a more virulent strain of rust from central France were made in Victoria in 1991 and more widespread releases followed in 1992.

Monitoring the impact of Phragmidium violaceum on two blackberry species, R. polyanthemus and R. ulmifolius began in 1984 and 1986 respectively at two sites in south-east Victoria and has continued spasmodically since. A reduction in total biomass of 56.2% for R. polyanthemus and 38% for R. ulmifolius was observed.

A common effect of the rust on both blackberry species was the significant reduction in daughter plant production, especially R. polyanthemus where daughter plant production was reduced by 95.8%. Since the release of the blackberry rust, winter defoliation to varying degrees occurs every year, an event which did not occur prior to the rust's release

 

Plant Protection Quarterly (1998) 13 (4) 182-185.