You are here: Plant & Food Science > Plant Protection > Fungal & Bacterial Plant Pathology

Print View Login

Fungal & Bacterial Plant Pathology

The fungal and bacterial plant pathology group is led by Associate Professor Eileen Scott. We are located in the Waite Main Building (labs N105, N107, N114 and offices N106, S102 and 203). The group conducts research on a range of plant diseases and microorganisms of importance in Australian agriculture and natural ecosystems. Since 1991, 25 PhD students and 19 honours students have successfully completed their degrees as part of this group. Dr Kerrie Davies, nematologist and visiting research fellow, is affiliated with the group.

Major Research Themes

• Epidemiology and management of diseases of horticultural crops, pulses and Australian native plants
• Effects of microorganisms on grape and wine quality
• Ecology of microorganisms and invertebrates associated with grapevines and Australian native plants

Horticultural Pathology

Dr Danièle Giblot Ducray – Postdoctoral Fellow (began 2006)

Challenges to the pistachio industry: bacterial dieback and nut quality

Dieback is a serious disease of pistachio that reduces yield and quality, and eventually kills trees. The likely causal agent is Xanthomonas translucens pistachio (Xtp) (Facelli et al. 2005). The pathogen appears to be transmitted among trees via pruning tools, although the natural point of entry is yet to be identified. Two genetically distinct groups of the pathogen, XtpA and XtpB, differ in host range and disease severity (Marefat et al. 2006). The aims of the current project are to: refine the existing PCR assay for pathogen detection, quantification and monitoring; investigate genetic diversity of Xtp to identify its likely origin and understand mechanisms of pathogenicity; evaluate chemical and cultural management strategies for controlling the disease in orchards; and establish a source of clean propagation material. The research is funded by Horticulture Australia Ltd and the Pistachio Growers Association, and is conducted in collaboration with Kathy Ophel Keller, SARDI, Cathy Taylor and Bob Emmett, DPI Victoria, Mildura.

Yvonne Smith - PhD candidate (began 2001)

Pink root disease of onion in South Australia

Pink root disease affects onion crops in the mid-Murray area of South Australia. Little is known about the epidemiology and management of this disease. Yvonne has investigated the susceptibility of onion cultivars to pink root and the possible role of ‘nurse crops’ (used to assist the establishment of onion seedlings), rotation crops and weeds as alternative hosts for the pathogen. She is now writing her thesis. Her project is co-supervised by Trevor Wicks, SARDI.

Cathryn Todd - PhD candidate (began 2005)

Rhizoctonia disease on potato: the effect of fungicides and interaction of micronutrients

Rhizoctonia solani is soil-borne fungal pathogen of Australian potato crops and causes various symptoms that reduce the quality and quantity of tubers available for the processing industry. Black scurf, caused by sclerotia (fungal resting bodies), is the most common symptom, but tuber malformation and necrosis of underground stems, stolons and roots are of more significance to the processing industry. Several sub-specific groups of R. solani (anastomosis groups, AG) have been found in potato fields that supply the fresh washed market (Balali et al. 1995). The aims of this project are to: determine the range of AGs isolated from potato fields that supply the Australian processing industry; establish the pathogenicity of the AGs to processing potatoes; evaluate the sensitivity of the AGs to fungicides registered for use on potato in Australia; and investigate the effect of micronutrients on disease severity. Cathryn’s project is co-supervised by Kathy Ophel Keller and Trevor Wicks, SARDI and is supported by the Potato Processing Research and Development Program (HAL).

Kerrie Davies – Visiting Research Fellow

Tritrophic interactions between nematodes, insects and their host plants

Two large groups of Australian, insect-associated nematodes are being studied. In a unique species-specific mutualism with fergusoninid flies, Fergusobia (Tylenchida) induces galls on myrtaceous plants. Schistonchus (Aphelenchida) is associated with fig-pollinating wasps, from fig sycones. Fergusobia is largely confined to Australia, but Schistonchus is found world-wide. Both are speciose genera, being used as models for international, collaborative studies of co-evolution. To date, preliminary descriptions of 11 new species of Schistonchus and descriptions of 22 species of Fergusobia have been made. Dr Davies provides morphological and systematic support for phylogenetic analyses based on sequencing of rRNA D2D3 and mtCO1. Comparisons of phylogenies of the respective nematodes and their host plants and insects will enable testing of co-speciation, host switching and possible hybridization.

Pulse Pathology

Amanda Benger – Honours candidate (2006)

Latent infection of lentils by Botrytis species?

Botrytis grey mould is a major disease of lentils in southern Australia. Previous research suggested that the pathogens, Botrytis cinerea and B. fabae, may infect foliage and, if the environment then becomes too dry for disease to develop, may persist as a latent infection, until activated by moisture. However, studies of plants inoculated in laboratory conditions showed that spores survived on the surface of lentil leaflets for 4 weeks and there was no evidence of latent infection. Thus the pathogen appears to survive via dormant spores, rather than latent infection. Amanda’s project was co-supervised by Jenny Davidson, SARDI.

Steve Coventry – PhD candidate (began May 2006)

Factors affecting short and long distance dispersal of fungal pests – chickpea ascochyta blight as a model

This project is part of the CRC for National Plant Biosecurity, and focuses on preparedness for incursions of exotic plant pathogens. Many fungi are spread over long distances via wind borne spores and over short distances via rain splashed spores. Information about the effects of environmental factors on spore dispersal will facilitate assessment of the potential disease risk for agrogeographical zones. Ascochyta pathogens of pulse crops, already present in Australia, with rain splashed asexual spores (conidia) and wind borne sexual spores (ascospores), provide the opportunity to study the relationship between the environment and spore dispersal, and to develop risk assessment strategies for exotic pests with similar spore dispersal patterns. This research involves collaboration with Jenny Davidson, SARDI and Moin Salam, Department of Agriculture and Food Western Australia.

Rohan Kimber - PhD candidate part-time (began 2005)

Epidemiology and significance of cercospora leaf spot (Cercospora zonata) of faba beans (Vicia faba) in southern Australia

Cercospora leaf spot is an emerging disease of faba beans in Australia. Little is known about the epidemiology of the disease and its effect on yield. Field and glasshouse studies are in progress to address questions about the impact of the disease and options for management and to provide information about sources of resistance in the Australian faba bean breeding program. This research, funded by the GRDC, will increase our understanding of cercospora leaf spot and facilitate improved integrated disease management, to the benefit the Australian industry. Rohan’s project is co-supervised by Jenny Davidson, SARDI and Jeff Paull.

Grape Pathology & Microbiology

Belinda Stummer – Postdoctoral Fellow (began 2000)
Effect of powdery mildew on grape and wine quality, and application of near infrared reflectance spectroscopy for disease assessment

Our research in the CRC for Viticulture has shown that even small amounts of powdery mildew on grapes can be detrimental to wine quality, resulting in an oil/viscosity mouthfeel in Chardonnay wine (Stummer et al. 2005). Wineries determine the amount of disease by visual assessment in the field and/or when grapes are received at the winery. However, visual inspection is subjective and does not give an accurate estimate of small amounts of affected grapes in large consignments of fruit. We have developed DNA-based tools to quantify powdery mildew in grapes and must (Stummer et al. 2006) and have used these tools to assess the potential of near infrared reflectance spectroscopy (NIR) for rapid and reliable quantification of powdery mildew in grapes. This research, in collaboration with the Australian Wine Research Institute and funded by the CRC for Viticulture (2000-2005), GWRDC and the Hardy Wine Company (2006-2007), will allow wineries to make more informed decisions about utilisation of fruit and must.

Dr Peter Crisp – Postdoctoral Fellow (began 2003)

Sustainable management of grapevine powdery and downy mildew

Sulfur is used routinely in vineyards to control powdery mildew, but may become a restricted input in organic viticulture in future (EC regulation 2092/91, IFOAM 1998) and may have undesirable side-effects on personnel and vineyard organisms. During his PhD project (funded by the ARC, 2000-2003), Peter identified milk, whey, oils and potassium bicarbonate as possible alternatives to sulfur for control of powdery mildew (Crisp et al., 2006). With GWRDC funding and logistical support from Temple Bruer Wines and Organic Crop Protectants, we have conducted field trials on a range of cultivars in New South Wales, Tasmania and South Australia, and demonstrated that these “soft fungicides” have no discernable effect on yield of grapes nor on wine quality. Also, tea tree oil products and ferrous sulfate have been identified as possible alternatives to copper fungicides for the control of downy mildew. Experiments are now in progress to assess various components of whey for efficacy in powdery mildew control, in collaboration with MG Nutritionals and Murray Goulburn Cooperative Ltd, Victoria.

Carol Walker - PhD candidate (began 2003)

Microbial population growth responses to novel powdery mildew control in an organic vineyard

This project is part of the above-mentioned GWRDC-funded research on sustainable management of grapevine powdery mildew. In recognition of the oenological significance of certain components of grapevine microbiota, the research aims to assess the effects of milk, whey and sulfur on grapevine microbial populations. A combination of morphological and molecular techniques is being used to determine the composition of microbial populations within and among treatments. This will elucidate effects of novel materials on grapevine microbiota and their potential to affect the chemical and sensory properties of juice and wine. Carol’s research is co-supervised by Paul Grbin, Wine and Horticulture, Trevor Wicks, SARDI and John Stephen, Australian Genome Research Facility.

Mei Tan - Honours candidate (2006)

Impact of milk and whey applied to control powdery mildew on wine quality – lactose and protein content

Also associated with GWRDC-funded research on sustainable management of grapevine powdery mildew, this research addresses the question of whether application of milk and whey to vines to control powdery mildew results in lactose residue in wine. Common wine yeasts do not metabolise lactose. Very small amounts of residual lactose may be detectable in wines, although well below the concentration that requires that lactose be stated on the label. Application of milk to vines may increase protein instability in the resulting wine. This research was supervised by Paul Grbin (Wine and Horticulture) and Eileen Scott.

Sarah Bainbridge-Smith - PhD candidate (began 2006)

Over-mature Shiraz and its effects on wine quality

Some vineyard managers allow Shiraz grapes to remain on the vine beyond normal ripeness to increase fruit flavour. Anecdotal evidence suggested that this practice may lead to increased volatile acidity in the resulting wine. During her Honours project (2005), Sarah identified microorganisms in must from over-mature Shiraz and during fermentation that may contribute to VA production and is now continuing this work for her PhD. She will investigate the microbiota associated with grape berries at different maturities and assess the impact of grape microbiota on the winemaking process. This project is supervised by Paul Grbin (Wine and Horticulture) and Eileen Scott, and is supported by the GWRDC and the McLaren Vale Grape, Wine and Tourism Association.

Key Papers

• Balali et al. (1995) Plant Pathology 44, 1050-1057.
• Crisp et al. (2006) Australian Journal of Grape and Wine Research 12, 203-211.
• Facelli et al. (2005) European Journal of Plant Pathology 112, 155-165.
• Marefat et al. (2006a) Plant Pathology 55, 639-649.
• Marefat et al. (2006b) European Journal of Plant Pathology 116, 57-68.
• Stummer et al. (2005) Australian Journal of Grape and Wine Research 11, 66-76.
• Stummer et al. (2006) Mycological Research 110, 1184-1192.

Collaborative Linkages

National:

• Amanda Able, Paul Grbin, Jeff Paull and Gary Taylor, School of Agriculture, Food & Wine, The University of Adelaide, South Australia.
• Andy Austin, School of Earth and Environmental Science, The University of Adelaide, South Australia.
• Jenny Davidson, Kathy Ophel Keller and Trevor Wicks, SARDI.
• John Stephen, Australian Genome Research Facility, South Australia.
• Bob Dambergs and Elizabeth Waters, Australian Wine Research Institute, South Australia.
• Bob Emmett and Cathy Taylor, Department of Primary Industries Victoria, Mildura.
• Moin Salam, Department of Agriculture and Food Western Australia.
• Katherine Evans, Tasmanian Institute of Agricultural Research, Tasmania.
• Sandra Savocchia, Charles Sturt University, New South Wales.
• Michelle Rowney, MG Nutritionals, Victoria.

International:

• David Gadoury, Cornell University, New York, USA.
• Robin Giblin-Davis, The University of Florida, Fort Lauderdale, Florida, USA.
• W. Douglas Gubler, University of California at Davis, California, USA.
• Louise Ferguson, UC Davis, California, USA.
• Russell Molyneux and Noreen Mahoney, United States Department of Agriculture, Berkeley, California, USA.
• Dani Shtienberg, Volcani Center, Israel.
• W. Kelley Thomas, Hubbard Genomics Center, The University of New Hampshire, Durham, New Hampshire, USA.

Past Members/Students: Where are they now?

PhD students (graduated since 2003) and first employment

• Peter Crisp (graduated 2004), Postdoctoral Fellow, The University of Adelaide.
• Don Gomez (graduated 2006), CSIRO Plant Industry.
• Sharmini John (graduated 2003), SARDI.
• Su-lin Leong (graduated 2006), Swedish University of Agricultural Sciences, Uppsala.
• Ben Killigrew (graduated from University of Western Australia, 2006), Manna Enterprises, Western Australia.
• Richard Lardner (graduated 2003), Postdoctoral Fellow, The University of Adelaide.
• Suzanne McKay (graduated 2005), SARDI.
• Alireza Marefat (graduated 2006), The University of Zanjan, Iran.
• Bita Naseri (graduated 2007), The University of Zanjan, Iran.
• Mark Sosnowski (graduated 2003), SARDI.

Honours students (graduated since 2003) and first employment

• Lachlan Palmer, BSc (graduated 2004), University of Adelaide.
• Julian Malone, BAgSc (graduated 2005) California Statewide Integrated Pest Management Program.
• Sarah Bainbridge-Smith, BSc (Oenology) (principal supervisor: Dr Paul Grbin, graduated 2005), PhD student, The University of Adelaide.
• Amanda Benger, BAgSc (graduated 2006), SARDI.
• Mei Tan, B Food Sc and Tech (principal supervisor: Dr Paul Grbin, graduated 2006).

Postdoctoral fellows (since 2003)

• Evelina Facelli, moved to School of Earth and Environmental Science, The University of Adelaide in 2006.
• Richard Lardner, moved to CSIRO Entomology in 2006.