Risk Assessment Of Exotic Plant Diseases To The Australian Rice Industry, With Emphasis on Rice Blast

A pest risk assessment was carried out using all available information found in the literature and also two softwares developed by the CSIRO, CLIMEX and DYMEX. CLIMEX was used to assess the suitability of the climate in Australian rice growing area for each pest/disease and then when necessary and possible, a pest/disease model was created with DYMEX and run with Australian climatic data. The Australian climatic conditions and/or the rice growing practices were found to be unfavourable for the majority of the exotic diseases. However, two diseases of rice (rice blast and kernel smut) and one plant parasitic nematode genus (root nematodes) were identified as having the potential to threaten the Australian rice industry if ever introduced in south eastern Australia

Exotic fungal spores in the Australian Plant Biosecurity context

This project aims to define the relative likelihood of, and means by which, exotic fungal spore incursions on or in different carrier materials can occur by assessing common pathogen species in Australia and likely entry pathways and develop effective methods of decontamination of such infested materials. In Australia, the risk of inadvertent introduction of exotic fungal pathogen particularly by spores is increasing. Many of these exotic fungal pathogens pose a threat to our agricultural, horticultural and natural ecosystems if introduced into Australia e.g. Ug99. This research will improve the current understanding of the different entry pathways of fungal pathogens to Australia. The research project will specifically focus on the role of different materials as fungal spore carriers and their effects on spore survivability using common fungal spores as a model to develop and apply prototype tools to detect the contamination of carrier materials with exotic fungal pathogen threats, and develop effective methods of decontamination of such contaminated materials

Long-term viability of the northern anthracnose pathogen, Kabatiella caulivora, facilitates its transportation and spread

The conidia and resting hyphae of the northern anthracnose pathogen of Trifolium species, Kabatiella caulivora, were effectively carried by, and maintained long-term viability on, a range of materials, including metals, fabrics, woods and plastics. Conidia and hyphae became thick-walled and melanized with time. There were significant (P < 0.001) differences in conidia/resting hyphae survival between carrier materials and between temperature regimes. At 23 °C/8 °C day/night, conidia and resting hyphae remained viable on steel, corrugated iron, galvanized steel, all tested fabrics, wood and random mixed materials for up to 8 months. At 36 °C/14 °C day/night, conidia and resting hyphae remained viable for up to 8 months, but only on cotton, denim, fleece, silk, leather, paper, plastic and all wood materials. At 45 °C/15 °C day/night, conidia and resting hyphae remained viable up to 8 months only on fleece wool, Eucalyptus marginata (jarrah wood) and paper. There were significant differences between carrier materials in their abilities to retain conidia and resting hyphae after washing (P < 0.001). Metabolic activity was confirmed for conidia and resting hyphae recovered after 8 months and K. caulivora colonies successfully re-established on potato dextrose agar. Findings confirmed the critical importance of materials as long-term carriers of viable K. caulivora conidia and resting hyphae, highlighting the potential for spread of a highly virulent K. caulivora race within and outside Australia via farming equipment, clothing and other associated materials. Results also have wider biosecurity implications for the transportation of fungal-infested carrier materials previously considered as low risk

Extended survival of Puccinia graminis f. sp. tritici urediniospores: implications for biosecurity and on-farm management

Puccinia graminis f. sp. tritici (Pgt), the causal organism of stem rust, is of global importance across wheat-growing countries. However, some epidemics commence without the obvious presence of ‘alternate’ or ‘green bridge’ hosts, suggesting urediniospores can survive in the absence of suitable host plants for many weeks. Testing a range of inert material types, including metals, plastics, fabrics and woods, highlighted a significant effect of material type and temperature on urediniospore viability (P < 0.001), with urediniospores remaining attached and viable on these materials (aluminium, paper, rubber, all fabric and all woods) for up to 365 days at 23/8 °C day/night. At 36/14 °C day/night, urediniospore viability was retained for a maximum of 300 days on denim and jute. Furthermore, at 45/15 °C day/night, urediniospores remained viable for a maximum of 180 days on cotton and jute. The frequency of recovery of attached urediniospores was also dependent upon the material type, with significant differences between materials in their abilities to retain urediniospores after washing (P < 0.001). Urediniospores recovered even after 300 or 365 days from the lower two temperature regimes successfully initiated infections of wheat seedlings. Results confirm the potential importance of inert materials as long-term carriers of viable Pgt urediniospores, highlighting risks of spread of new pathotypes and strains across wheat-growing regions, the significant biosecurity implications for contaminated carrier materials, and its likely survival across seasons without a host

Movement of pathogens between horticultural crops and endemic trees in the Kimberleys

Recently a survey of endophytes associated with boabs (Adansonia gregorrii) and associated tree species in the Kimberleys, Western Australia has resulted in the description of seven new species in the Botryosphaeriaceae (Pavlic et al. 2008). Additionally several common species of Lasiodiplodia, (L. theobromae, L. pseudoptheobromae and L. parva) were also isolated as endophytes of endemic tree species. Concurrently, surveys in the Ord River Irrigation Area (ORIA) have revealed Mangiferum indica trees showing symptoms of dieback and cankers. In this project we isolated, identified and determined the pathogenicity of fungi associated with these cankers

Pathogenic Botryosphaeriaceae associated with Mangifera indica in the Kimberley Region of Western Australia

Members of the Botryosphaeriaceae, in particular Lasiodiplodia theobromae, Neofusicoccum parvum, N. mangiferum and Botryosphaeria dothidea, commonly cause stem cankers, dieback and stem end rot of mangoes worldwide. In the current study, eight taxa of Botryosphaeriaceae were identified as canker-associated fungi, pathogens, potential pathogens or endophytes of mangoes in the Kimberley, Australia. These include Neoscytalidium novaehollandiae, Ne. dimidiatum, Pseudofusicoccum adansoniae, P. ardesiacum, P. kimberleyense, Lasiodiplodia sp. 1, L. iraniensis and L. pseudotheobromae. The pathogenicity of a selection of these species toward fruit and branches was tested. All were pathogenic to mango in comparison to the control, with Lasiodiplodia spp. being the most pathogenic. It appears that either geographic isolation or the unique growing conditions in the Kimberley may have provided an effective barrier to the acquisition or establishment of known botryosphaeriaceous pathogens. Wounds caused by mechanical pruning may provide an entry point for infection, whilst severe pruning may increase plant stress