Ground Cover North : Ground Cover 053 December-January 2005 - North
Mazda B and E-Series light trucks, utes and vans are built to get the job done. As tough on the outside as they are comfortable on the inside, B-Series are available in two or four wheel drive, petrol or turbo-diesel engines. And there's also the Freestyle Cab with a pillarless door system for easy access. E-Series MAZ6778/GC CHE weed management 14 decemBeR 2004 By Emma LEonard There are plenty of insects and fungi that attack wild radish – but fnding those that are exclusive to wild radish is the challenge for researchers looking for a biocontrol agent. Biocontrol is regarded as the best alternative to herbicides, which are coming up against resistance. Having searched in Europe, researchers at CSIRO Entomology and the CRC for Australian Weed Management are now investigating potential biological control agents that might already be in Australia. Wild radish originates from Europe and North Africa and is now a major weed of the WA grainbelt and a problem in all cropping districts in southern Australia. Herbicide resistance is an increasing problem with several populations showing resistance to more than one herbicide group. In 1999 the GRDC com- missioned the CSIRO’s Dr John Scott to search for potential biological control agents in Europe and North Africa. His extensive collecting program based at the CSIRO European Laboratory involved French scientists Mirielle Jourdain and Janine Vitou. They identifed 16 insect and fungal parasites as potential biocontrol agents. After controlled feld testing, none of these was found to be suffciently exclusive to wild radish, making the risk of cross-over to other Brassica species, such as canola, too great. “Our work established that biological control of wild radish is feasible, providing we can fnd exclusive agents that can be transferred to the feld in suffcient numbers,” explains Dr Scott. “As the European agents were not exclusive to wild radish we turned our attention to fungal pathogens of wild radish that may already exist in Australia. From our work in Europe the funghi are of particular interest as these offer the opportunity to develop mycoherbicides.” In 2003, Aaron Maxwell, a member of the CRC for Australian Weed Management based at CSIRO, surveyed 75 sites across the cropping districts of WA looking for disease on wild radish. Many pathogens were found to attack the weed and of these two have features of specifc value for biological control. These pathogens, downy mildew (Hyaloperonospora parasitica) and Brassica leaf spot (Alternaria), are widely spread across WA and have caused signifcant damage to wild radish in some places. “Both pathogens attack the seedling weeds and we are now establishing if they are host-specifc to wild radish,” says Mr Maxwell. “I am comparing the strains of downy mildew in Australia with those previously found in Europe and North Africa, to try to identify host-specifc strains.” Downy mildews cannot be grown on artifcial media, making it inappropriate for their development as mycoherbicides. However, Mr Maxwell believes it may be possible to conserve these pathogens in the cropping system in such a way as to speed up reinfection in autumn. The other approach Dr Maxwell is investigating is the development of Alternaria into a mycoherbicide. This could be sprayed on to a radish- infested site in the same way that a conventional herbicide is applied. The criteria for pathogen selection for mycoherbicide development are that they need to: n infect wild radish species; n kill seedlings or young plants; n be host-specifc to wild radish; n be easily propagated or mass produced; n have poor ability to spread off- site; and n have low persistence in the feld the season after application. This two-year research project has another nine months to run before more detailed results can be released but is hoped that this biocontrol option will offer suffcient potential to allow further research to develop a commercially available biocontrol solution for wild radish. GrdC rESEarCH CodE cRw 5, program 3 For more information: aaron maxwell, 08 9333 6159, email@example.com Radish control needs exclusive tastes narrowing the search: aaron maxwell is now focusing his work on two pathogens.
Ground Cover 054 February-March 2005 - North
Ground Cover 052 October-November 2004 - North