This document was originally published on the website of the CRC for Australian Weed Management, which was wound up in 2008. To preserve the technical information it contains, the department is republishing this document. Due to limitations in the CRC’s production process, however, its content may not be accessible for all users. Please contact the department’s Weed Management Unit if you require more assistance. factsheet Release of biological control agents: additional strains of leaf-rust fungus to control blackberry

Background Project: National blackberry Commonwealth, State and Local biological control program in governments, Natural Resource European blackberry (Rubus fruticosus partnership with the community to Management regions. aggregate) is one of Australia’s 20 release and monitor the establishment, Location: Across Australia Weeds of National Significance. persistence and impact of new rust Blackberry infests about 8.8 million strains in blackberry-infested regions. VET sector resource: RTD3707A hectares of southern Australia (more Release biological control agents Participants: Land managers, than the area of Tasmania). At least 15 CSIRO, University of Tasmania, different but closely related taxa (for simplicity referred to as species) of weedy blackberry have been identified in Australia. Many species have the Ideal conditions reduced the biomass of at least two potential to spread further within the species of the R. ruticosus agg. climatic limits of blackberry's range. Since its introduction this rust fungus has provided useful control in some Work in the 1990s by the Weeds CRC Blackberry can be managed using a improved understanding of genetic situations. In some areas climatic range of control methods including variation in blackberry, and improved conditions are unsuitable for this rust’s chemical, physical and biological prospects for its biological control. establishment and growth, or the rust control. Biological control (eg using rust fungus) is particularly useful in large strains are not suited to the blackberry Characteristics of the rust species.

rust to control blackberry rust to control inaccessible areas. The rust fungus P. violaceum completes The most significant impacts of rust on its life cycle on members of the host Rust fungus susceptible blackberry species have species R. fruticosus agg. been in localities where the annual The rust fruiting bodies (spores) Presence in Australia rainfall is greater than 800 mm and the damage the leaves. One type is bright The leaf-rust fungus Phragmidium average maximum daily temperature yellow, wind-dispersed and responsible o violaceum is present on European for the month of January is about 20 C. for epidemics during the growing season. Another is black, produced at weedy blackberry in Australia. Since introduction to south-east the end of the growing season and The rust has been introduced on a Victoria P. violaceum has significantly allows the rust to overwinter on number of occasions. There was: infected plants.

• an unauthorised introduction in The rust infects leaves and occasionally 1984; and green stems, leaf stalks, sepals, and • authorised releases of strain F15 as a unripe fruits. It obtains nutrients and biological control agent in 1991 and water from blackberry plant cells 1992 after extensive host-specificity reducing its ability to grow and testing. reproduce.

Spread of the rust disease throughout The rust fungus is capable of reducing southern Australia was rapid and the Blackberry infected with the rust fungus, daughter plant production of rust now occurs in most blackberry Phragmidium violaceum. blackberry, which reduces its Photo: CSIRO Entomology infestations in Australia. vegetative spread.

Cooperative Research Centre for Australian Weed Management • Factsheet Additional rust strains has enabled the trialling of various including release guidelines. Success of techniques and timing, before the releases will be measured by A garden of European genotypes of embarking on a large-scale national evidence of rust strains persistence and blackberry found in Australia was rust release program. impact at selected sites. Natural spread established in France in 1999 by CSIRO of the rust strains should lead to self- and the Weeds CRC. The aim was to Identifying additional strains sustaining biological control. “trap” additional strains of P. violaceum In the field, additional rust strains that are virulent on these plants. These Collection of samples cannot be visually distinguished from additional rust strains would enhance existing rust populations. Participants in the Weeds CRC biological control options in Australia. blackberry identification workshops will A molecular diagnostic tool is being be encouraged to collect blackberry Selection and testing developed to distinguish between rust specimens from severely weed infested strains. This technique will allow During 2002, eight additional strains of sites in their regions. (See Weeds CRC extensive screening of rust samples to the rust were selected from the trap Factsheet Weed Management: garden and imported and tested in the monitor establishment of recently collecting blackberry specimens for Canberra CSIRO High Security released strains. identification).

Quarantine Facility. Their virulence and Pressed blackberry specimens and their their host-specificity was determined. Future community details should be sent to Dr Louise involvement Morin at CSIRO Entomology who will Release in Australia rust to control blackberry rust to control organise lodgment at herbaria and In 2004 Biosecurity Australia approved National release of rust have their identification confirmed. Information compiled about the sites the release of additional strains of rust. Funding is being sought to establish a will be used to map various blackberry First releases were made in April 2004. coordinated national release and types and devise the rust release Limited releases of additional rust monitoring program for the additional strains have been made in NSW and strategies. strains of blackberry rust. Assuming WA (by CSIRO) and in Victoria (by funding is received the project will Department of Primary Industries). This commence in April 2006.

Suitable release sites

The new project will require sites suitable for release of the additional rust strains. Strategically located release sites will be identified through an Expression of Interest process involving the community. Community- Release of additional blackberry rust strains. based rust releases will be supported Inoculation of blackberry with rust fungus. Photo: CSIRO Entomology Photo: CSIRO Entomology with field days and written information

For further information visit the Weeds CRC’s website: www.weeds.crc.org.au

CRC for Australian Weed Management Written by: Annette Beer, Education Officer, Established and supported Waite Road, Urrbrae Weeds CRC (DPI Wagga Wagga, NSW); and Dr under the Australian PMB 1, Waite Campus Louise Morin, Weeds CRC, (CSIRO Entomology, Government’s Cooperative Glen Osmond, SA 5064 GPO Box 1700, Canberra, ACT 2601). Research Centres Program Further reading: Weeds CRC Factsheet Collecting T 08 8303 6590 blackberry specimens for identification; Weed F 08 8303 7311 Management Guide: Blackberry, (NHT & Weeds E [email protected] CRC); and www.ento.csiro.au/weeds/blackberry Ref: 43/2005/fs

Disclaimer: This publication is provided for the purpose of disseminating information relating to scientific and technical matters. Participating organisations of the Weeds CRC do not accept liability for any loss and/or damage, including financial loss, resulting from the reliance upon any information, advice or recommendations contained in this publication. The contents of this publication should not necessarily be taken to represent the views of the participating organisations.

Cooperative Research Centre for Australian Weed Management • Factsheet