Publications archive - Biodiversity
Key departmental publications, e.g. annual reports, budget papers and program guidelines are available in our online archive.
Much of the material listed on these archived web pages has been superseded, or served a particular purpose at a particular time. It may contain references to activities or policies that have no current application. Many archived documents may link to web pages that have moved or no longer exist, or may refer to other documents that are no longer available.
An abiotic or biotic disorder?
A multi-disciplinary investigation of an unknown etiology
Department of the Environment and Heritage, August 2004
A study of 40 E. camaldulensis, E. leucoxylon or E. cladocalyx trees from South Australia and Victoria was undertaken to investigate the role of biotic and abiotic causal agents in the plant die-back syndrome, Mundulla Yellows (MY). A further six E. arenacea trees were examined at Desert Camp in SA, in floristic and soil surveys.
Floristic surveys in SA, revealed that MY-like symptoms were present in plants with vastly different taxonomic positions. Conversely, closely related species were affected to markedly different degrees. Long-lived plant species were affected with MY symptoms, while annuals were apparently unaffected. Thirty-five new species, demonstrating MY-like symptoms, were identified in this study (additional to those listed in Mundulla Yellows Task Group, 2004. A Report on Mundulla Yellows in Australia. The Natural Resource Policies and Programs Committee of the Natural Resource Management Ministerial Council.).
In biotic investigations, no plant fungi, bacteria or phytoplasmas were identified as being associated with MY symptoms. Predominantly, ubiquitous saprophytes or secondary pathogens were isolated from symptomatic and asymptomatic sites, with slightly higher numbers recorded at asymptomatic sites. There was no association between nematodes and MY symptoms, nor was there an association between insect pests or vectors and MY, in an assessment of ten study sites.
In this study, MY symptoms were not transmissible by seed, mechanical inoculation (Victorian sites tested only) or grafting of selected material in repeated experiments. However, virus-like particles were detected at a single symptomatic SA study site, using Transmission Electron Microscopy (TEM). The characterisation (including mechanical inoculations) and the association of the virus-like particles with symptom expression are being further investigated. The absence of these particles in symptomatic trees from other sites suggests that they are not the primary cause of MY.
The full report will be published in several scientific journals shortly. This site will be updated with details of the exact journals shortly.