Fungal & Bacterial Plant Patholog
The fungal and bacterial plant pathology group is led by Professor Eileen Scott. Most of us are located in the Waite Main Building (labs N105, N107, N114, S103 and offices N103, 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, 29 PhD students and 21 honours students have successfully completed their degrees as part of this group. Dr Kerrie Davies, nematologist and visiting research fellow, and Dr Maarten Ryder, soil biologist and plant pathologist, are 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
Eileen’s group currently comprises postdoctoral fellows, PhD, Masters and Honours students, and has received funding from the ARC, rural industry research and development corporations, industry groups, and state and local government organisations.
Current research group members
Current group members and research highlights (grouped according to research area) are:
Ms Pooja Vashist
Research assistant (began 2010)
The foliar diseases powdery mildew and botrytis grey mould affect a wide range of horticultural crops and cause significant economic losses worldwide, particularly within viticulture. Due to the development of pathogen resistance to synthetic fungicides and increased restrictions on the use of sulfur, novel alternative treatments for disease control have been identified. In previous studies milk has been identified as an effective control for powdery mildew, comparable to the action of sulfur (Crisp et al, 2006), however little is known about the mode of action of milk components in plant-pathogen systems. The aims of this research are to understand the mode of action of milk fractions in the control of powdery mildew and botrytis grey mould in horticultural crops; to contribute to the development of new products derived from milk for the control of these diseases, and to evaluate the efficiency of product formulations in small glasshouse and field trials on a range of crop species. This research may lead to the development of a new fungicide for the management of foliar diseases in horticulture, against a range of plant fungal pathogens.
This research project is supervised by Eileen Scott, Dennis Taylor and Otto Schmidt in collaboration with Paul Grbin and Trevor Wicks, SARDI, and is supported by the ARC, MG Nutritionals Pty Ltd, Temple Bruer Wines, Organic Crop Protectants Pty Ltd and Transgrain Technologies.
PhD candidate (began 2008)
Apparently endemic in Australia, the pistachio dieback pathogen, Xanthomonas translucens pv. pistaciae (Xtp) (Facelli et al., 2001, Giblot-Ducray et al., 2009) is being used as a local model to assess the effectiveness of existing eradication strategies for systemic bacterial pathogens of woody perennials which are considered high-priority emergency plant pests in Australia. Burial and burning are two accepted means of disposal of diseased plant material. However, there is little or no information on the survival of bacterial pathogens following burial or burning of infected wood.
The project aims to evaluate the efficacy of burial and burning as means of safe disposal of diseased wood. Infected pistachio wood was buried in orchard soil in pots or left on the soil surface in August 2008 and has been retrieved monthly to assess survival of Xtp. Viable Xtp has been detected in some wood samples buried for 28 months. In studies of the survival of the pathogen in burned wood, viable Xtp was not detected in partially burned wood, charcoal or ash. However, it was detected in some unburned wood buried 5 cm below, or suspended 20 cm and 50 cm above the pit surface where the fire did not reach or was not intensive. Work in progress includes:
- identification of the lethal temperature for the pathogen;
- isolation of bacteria associated with buried wood to screen for antagonists of Xtp; and
- the potential for Xtp to enter into the viable but non-culturable state in response to environmental conditions during burial.
The natural means of spread of bacterial dieback disease of pistachio is unknown. The pathogen, Xanthomonas translucens pv. pistaciae, can be spread via pruning tools and growers have been advised to minimise spread through hygiene practices and application of quaternary ammonium disinfectant to pruning wounds. However, effective control measures are still lacking. Biological control using antagonistic bacteria has potential as a means of disease management. The aim of this research is to investigate the efficacy of selected bacterial antagonists, originally obtained from pistachio wood, in inhibiting X. translucens in detached twigs and living trees. The results from this project build on those obtained by former Masters student Asmah Salowi and will explore further the potential of biological control in managing pistachio dieback.
Nga's project is co-supervised by Danièle Giblot Ducray, with assistance from Maarten Ryder, and is supported by AusAID.
PhD candidate (resumed interrupted studies in 2008)
Erminawati is investigating the use of the essential oil, citral, as a means of controlling post-harvest spoilage of oranges. Green mould, blue mould and sour rot are the main causes of spoilage of oranges. These diseases are caused by the fungi Penicillium digitatum, Penicillium italicum and Geotrichum candidum, respectively. Citral reduced or prevented germination of spores of these fungi in vitro when incorporated into agar and when applied as a solution. Vapours of citral and its isomers geranial and neral inhibited development of all three fungi, whereas a range of citral-related compounds was less effective. When used in a closed system to fumigate oranges, citral delayed the onset of sour rot but effects on green and blue mould were more variable.
Eutypa dieback of grapevines is caused by Eutypa lata. Ascospores of the fungus land on wounds exposed by pruning and colonise the xylem vessels. Currently, no chemical fungicides are registered for the control of eutypa dieback of grapevines in Australia and cultural practices are only partially effective in controlling the disease. Folicur (tebuconazole), garlic and lactoferrin have recently been identified to be effective against E. lata, but further evaluation is required to optimise application rates and timing (Sosnowski et al. 2010). The objectives of this project are to: examine the effect of ascospore inoculum concentration on infection of pruning wounds in a detached cane assay; determine the efficacy of Folicur fungicide as a wound treatment when applied at different times before and after inoculation; assess garlic and lactoferrin as natural alternatives to fungicides for pruning wound protection.
Merriam's project is co-supervised by Mark Sosnowski, with assistance from Mathew Ayres, and is supported by AusAID.
Honours candidate (began 2011)
The growth and activity of soil-borne plant pathogens and biocontrol agents is affected by several environmental factors, including soil temperature, moisture and pH. The effect of abiotic factors on the activity of biocontrol agents is important because it not only influences pathogen behaviour and disease development, but also biocontrol efficacy. In addition, environmental factors also differ greatly between different cropping environments, for instance dryland agriculture and horticulture. However, the potential for biocontrol agents isolated from one cropping environment to be applied to others has not been widely studied. In particular, there is a dearth of information on how these factors affect the activity of endophytic actinomycetes, which were discovered relatively recently and have proven effective in controlling soil-borne pathogens in field conditions. This project will investigate the effects of soil moisture and pH on the biocontrol efficacy of selected endophytic actinomycete strains, which were isolated from cereals, in controlling damping-off in capsicum (Capsicum annuum) caused by Pythium aphanidermatum.
Li's project is co-supervised by Amanda Able and Chris Franco (Flinders University).
PhD candidate (began 2009)
Ascochyta blight (or blackspot) is an important disease of field peas in South Australia. The disease has been attributed to a complex of the fungal pathogens Mycosphaerella pinodes, Phoma medicaginis var. pinodella and Ascochyta pisi. The fungus Phoma koolunga has recently been identified and characterised in association with Ascochyta blight of field peas in South Australia (Davidson et al., 2009). Little is known about the impact and role of this pathogen in the disease complex. In this project, aspects of the biology and epidemiology of this pathogen and disease will be investigated. Studies may include the effect of temperature on growth of the fungus, the effects of temperature and wetness period on disease development, and dispersal of spores of P. koolunga by wind and rain. The host range of the fungus and aspects of the interaction between isolates and cultivars of field pea may also be explored.
Steve Coventry – Factors affecting short and long distance dispersal of fungal pests – chickpea ascochyta blight as a model
PhD candidate (began May 2006)
This project is part of the CRC for National Plant Biosecurity, and focuses on preparedness for incursions of exotic plant pathogens. The effects of environmental factors on spore dispersal are being investigated to facilitate assessment of the potential disease risk for agrogeographical zones. Ascochyta rabiei, causal agent of the endemic disease ascochyta blight of chickpea, is being used as a model to study the relationship between the environment and spore dispersal, and to develop risk assessment strategies for exotic pests with similar spore dispersal patterns. The spread of disease was assessed in field trials in 2006-2008, using chickpea cultivars of varying susceptibility to ascochyta blight; data for wind and rainfall were collected also. The effect of wind speed, rain-splash and a combination of the two on spore dispersal was evaluated in a purpose-built wind and rain simulator. Data for weather factors and dispersal of the pathogen and the disease are being used to adapt the Spatiotemporal Model for Simulating the Spread of Anthracnose in a Lupin Field 1 (AnthracnoseTracer) to predict the spread of ascochyta blight in chickpea.
This research involves collaboration with Jenny Davidson, SARDI, and Moin Salam, Department of Agriculture and Food Western Australia, and is supported by the Cooperative Research Centre for National Plant Biosecurity.
PhD candidate part-time (began 2007)
Ascochyta blight (synonym: blackspot) is the most important disease of field peas in Australia. No major gene resistance has been discovered and fungicides are generally uneconomic. The most effective control strategy is to delay sowing until after the release of ascospores in autumn. A model, ‘Blackspot Manager’, has been developed in Western Australia that predicts % ascospore release from ascochyta blight-infested pea stubble for a given time of sowing. This model is used in Western Australia and South Australia to determine optimum sowing dates for field peas to reduce the risk of ascochyta blight from primary inoculum. In this project research is being conducted to determine the likely disease severity associated with the predictions from ‘Blackspot Manager’ in different rainfall zones in South Australia. This disease is caused by a complex of fungal pathogens including Mycosphaerella pinodes, Phoma medicaginis var. pinodella and Ascochyta pisi. A fourth pathogen (a Phoma species) has been isolated from ascochyta blight-afffected field peas in South Australia. This pathogen has been described and compared with the other causal pathogens, in artificial media and on plants in controlled conditions. For more information, see the SARDI website.
Jenny’s project is co-supervised by Moin Salam, Department of Agriculture and Food Western Australia and is supported by the South Australian Grains Industry Trust.
PhD candidate (began 2010)
Blackspot of field pea is caused by four fungal pathogens, one of which, Phoma koolunga, was described only recently (Davidson et al., 2009). This disease reduces both production and yield of pea around the world including Australia and South Australia. The biology and epidemiology of P. koolunga are poorly understood. This project focuses on aspects of epidemiology such as survival, seed infection, alternative hosts, the existence of a teleomorph and resistance of field pea to P. koolunga. Knowledge gained will assist in management of blackspot of pea.
Rohan Kimber – Epidemiology and significance of cercospora leaf spot (Cercospora zonata) of faba beans (Vicia faba) in southern AustraliaPhD candidate part-time (began 2005)
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 will increase our understanding of cercospora leaf spot and facilitate improved integrated disease management, to the benefit the Australian industry.
PhD candidate (began 2007)
Plant disease surveillance is important for early detection of incursions, monitoring disease status during eradication programs, and to demonstrate that an area is free of a particular pathogen, for trade purposes. The combination of air sampling and PCR-based diagnostics offers fast, reliable, accurate, sensitive and specific means of detecting air-borne fungal pathogens. This project aims to apply quantitative PCR techniques, in combination with air sampling, for detection of air-borne fungal plant pathogens, and to determine the strengths and constraints of these tools in relation to plant health surveillance.
Methods for PCR-based detection and quantification of three model fungal pathogens from air samples have been developed. The model pathogens are Leptosphaeria maculans, causal agent of blackleg of canola, Mycosphaerella pinodes, one of a complex of pathogens causing blackspot of field pea, and Ascochyta rabiei, which causes ascochyta blight of chickpea. The PCR-based methodology has proved to be both sensitive and specific to the three model pathogens. Monitoring in 2008 indicated that the PCR-based tests were in good agreement with microscopy, and there was broad agreement with trap plant data. The methodology enabled truthing of epidemiological models for blackleg and blackspot.
Bonny’s project is co-supervised by Jenny Davidson and Kathy Ophel-Keller, SARDI and Moin Salam, Department of Agriculture and Food Western Australia, and is supported by the Cooperative Research Centre for National Plant Biosecurity.
Dr Evelina Facelli – ARC Postdoctoral Research Associate (part-time, began 2009) and Kueh Kiong Hook – PhD candidate (began 2007)
Impact of Phytophthora cinnamomi on native vegetation in South Australia
Phytophthora dieback, caused by the fungus-like pathogen Phytophthora cinnamomi, threatens many Australian native plants, as well as woody horticultural crops. This research aims to address the gap in our knowledge about the effect of Phytophthora dieback on native vegetation in South Australia that has been listed as threatened or may become threatened by extinction. Knowledge of the areas of the state and plant species at risk from the disease and of factors that affect the patterns and rate of spread of the pathogen in representative plant communities will facilitate the development of sustainable management strategies.
Methods have been developed for assessing the susceptibility of rare plant species in the greenhouse. Three to six month-old plants are inoculated by placing pine wood plugs colonized by the pathogen into the potting mix. All experiments include a known susceptible species, to account for the variability in germination and growth of the test plant species. Phytophthora-infested sites at Mount Bold Reservoir reserve and Scott Creek Conservation Park, South Australia, have been established to study the spread of pathogen and disease in native vegetation. Vegetation has been assessed. Numbers of dying and dead grass trees (Xanthorrhoea semiplana) are being counted and soil samples collected for isolation of P. cinnamomi annually to determine the rate of disease and pathogen spread. The effects of competition between plant species and the role of actinomycetes as possible antagonist of the pathogen are being examined also.
This research is conducted in collaboration with Department for Environment and Heritage, South Australia Adelaide-Mt Lofty NRM Board, Adelaide Hills Council, City of Tea Tree Gully Council, Department of Transport, Energy and Infrastructure, Forestry SA, PIRSA Forestry, SA Murray Darling Basin NRM Board and SA Water. Mr Kueh’s project is co-supervised by Amanda Able, Jose Facelli, School of Earth and Environmental Sciences and Chris Franco, Flinders University and is supported by the Government of Sarawak.
Visiting Research Fellow
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 28 species of Fergusobia have been made, and the genus has been revised.
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.
Maarten is a soil biologist and plant pathologist with a research background in the biological control of soil-borne diseases in field and horticultural crops. He is assisting several of the graduate students with their research projects. For example, he is working with projects on biological control of pistachio dieback, interactions between Pythium, Capsicum, soil conditions and potential biological control agents, and disease on field peas caused by Phoma koolunga. Maarten is also assisting with publications, grant writing and the delivery of course material in Classical Diagnostic Methods in Plant Health module in the Masters in Plant Health and Biosecurity.
- Davidson et al. (2009) Mycologia 101, 120-128.
- Giblot-Ducray et al. (2009) Systematic and Applied Microbiology 32, 549-557.
- 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.
- Stummer et al. (2005) Australian Journal of Grape and Wine Research 11, 66-76.
- Davies et al. (2010) Zootaxa 2633, 1-16.
- Amanda Able, Chris Ford, Paul Grbin, Jeff Paull, Otto Schmidt and Dennis Taylor, School of Agriculture, Food & Wine, The University of Adelaide, South Australia.
- Jose Facelli, Andy Austin and Gary Taylor, School of Earth and Environmental Science, The University of Adelaide, South Australia.
- Jenny Davidson, Kathy Ophel Keller, Mark Sosnowski and Trevor Wicks, SARDI.
- John Stephen, Australian Genome Research Facility, South Australia.
- Bob Dambergs, Australian Wine Research Institute, South Australia.
- Chris Franco, Flinders University, 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.
- David Bruer, Temple Bruer Wines, South Australia.
- Ross Crittenden, MG Nutritionals, Victoria.
- Renate Velzeboer, Department for Environment and Natural Resources, South Australia.
- 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.
- Natsumi Kanzaki, Forestry and Forest Products Research Institute, Ibaraki, Japan.
- Neil Parkinson, Central Science Laboratories, UK.
- Sonja Scheffer, USDA, Baltimore, USA.
- Dani Shtienberg, Stanley Freeman and Giora Kritzman, Volcani Center, Israel.
- W. Kelley Thomas, Hubbard Genomics Center, The University of New Hampshire, USA.
- 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), Landcorp, 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.
- Sarah Palmer (graduated 2008, principal supervisor: Dr Amanda Able) , University of Warwick, UK
- Matchima Naradisorn (graduated 2008, principal supervisor: Dr Amanda Able), Mae Fah Luang University, Thailand
- Mark Sosnowski (graduated 2003), SARDI
- Cathryn Todd (graduated 2009), SARDI
- Yvonne Smith (graduated 2009), onion industry, South Australia
- Asmah Salowi (graduated 2010), Government of Sarawak Department of Agriculture
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, B Oenol (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). employment in Singapore.
- Adrian Loschiavo BSc (Agricultural Science) (graduated 2009), Scholefield Robinson Horticultural Services, Adelaide
- Sue Pederick, BAgSc (graduated 2010), SARDI
- Joshua Roberts, B Oenol (principal supervisor: Dr Paul Grbin, graduated 2011), wine industry, South Australia
Postdoctoral fellows (since 2003)
- Daniele Giblot-Ducray, moved to SARDI in 2009
- Peter Crisp, moved to SARDI in 2006
- Richard Lardner, moved to CSIRO Entomology in 2006
- Suzanne McKay, moved to the Arthritis Foundation in 2010