Charles Sturt University
Charles Sturt University

Plant Pathology

Research on pests and diseases of grapevines encompasses a whole-of-system approach with the current focus being pathogen identification, epidemiology and pest & disease management and the impact of diseases on grape and wine composition.

Selected Research Projects

Production of volatile organic compounds (VOC) with biocontrol properties by Auerobasidium Pullulans

Team leader: Prof Chris Steel (NWGIC)

Team members: Yalage Don Sashika Madhupani (NWGIC PhD student), Prof Leigh Schmidtke (NWGIC), Dr Joanna Gambetta (NWGIC)

Auerobasidium pullulans is a yeast-like fungus that is frequently associated with the surfaces of several plant species. The organism has biocontrol properties and has previously been evaluated for the control of a number of fungal diseases of horticultural crops, including wine grapes. This project aims to elucidate the cultural and environmental factors that influence the biocontrol properties of A. pullulans. These properties may include the production of volatile organic compounds (VOC) which are potentially antimicrobial. This study aims to investigate the activity of these compounds against Alternaria solani and Botrytis cinerea, two fungal pathogens of tomatoes and grapes. The mode of action of the VOCs produced by A. pullulans will be investigated using a combination of techniques involving microscopy and enzyme assays. VOC chemical identity will be elucidated by Solid Phase Micro Extraction-Gas Chromatography-Mass Spectrometry (SPME-GC-MS). The work will lead to a better understanding as to how isolates of A. pullulans function as biocontrol agents.

Fumonisin formation in Australian Aspergillus species and the fate of fumonisin during grape and wine production

Team leader: Prof Chris Steel (NWGIC)

Team members: Dilhani Perera (NWGIC PhD candidate), A/Prof Sandra Savocchia (NWGIC), A/Prof Paul Prenzler (Charles Sturt University/SAWS)

The fumonisins are a group of mycotoxins produced by Aspergillus and other fungal species.Based on the current toxicological data, fumonisin B2 has been classified as a potential human carcinogen. Fumonisin has been recorded in both fresh and dried-grapes as well as in wine made from grapes infected with fungal moulds. This project will assess the capacity of Australian Aspergillus isolates associated with grapes for fumonisin production. The project aims to elucidate the environmental factors that predispose species of Aspergillus to produce fumonisin.  The fate of fumonisin from the vineyard through to finished wine will be investigated. The project will lead to a greater understanding of the impact that Aspergillus species have on grape and wine production.

Determining thresholds for bunch rot tolerance in wine and detection of unwanted fungal aromas

Team leader: Prof Chris Steel (NWGIC)

Team members: Prof Leigh Schmidtke (NWGIC), Dr John Blackman (NWGIC), Dr Andrew Clark (NWGIC), Dr Joanna Gambetta (NWGIC)

Fungal rot of grapes can be caused by a range of organisms. While bunch rot of grapes is most commonly associated with Botrytis cinerea (grey mould) there are a number of other pathogenic fungi that can attack grapes close to harvest. These other fungi include species of Aspergillus and Penicillium and other fungi more commonly associated with sub-tropic viticulture, such as Colletotrichum (ripe rot) and Greeneria (bitter rot). Lack of fungicide availability due to nil maximum residue limits (MRL) restrictions in destination export countries means that many effective fungicides cannot be applied to wine grapes post veraison. As a result, disease control often fails and wine makers are faced with the prospect of processing grapes of less than perfect quality. Using a combination of chemical and sensory analysis this project aims to more accurately define the impact the different types of fungal rots have on grape and wine quality. With this knowledge thresholds for bunch rot contamination of wine grapes can be set. This will help grape growers and winemakers to make harvest decisions when grape bunch rots are a problem.

Grapevine Trunk Disease Management for vineyard longevity in diverse climates of Australia

Team leader:  A/Prof. Sandra Savocchia (NWGIC)

Team members: Dr Regina Billones-Baaijens (NWGIC), Prof Chris Steel (NWGIC), Ms. Meifang Liu (NWGIC), Dr Mark Sosnowski (SARDI), Mr Matthew Ayres (SARDI)

Eutypa dieback (ED) and botryosphaeria dieback (BD) are major grapevine trunk diseases (GTDs) worldwide, threatening the sustainability of Australian vineyards. Australian vineyards are increasingly affected by GTDs, threatening the sustainability of the wine industry, which contributes $40 billion to the Australian economy.

The “Grapevine trunk disease management for vineyard longevity in diverse climates of Australia” is a collaborative project with researchers at NWGIC and the South Australian Research and Development Institute (SARDI) and is funded by the Wine Australia. The objectives of the project include investigating spore dispersal patterns of ED and BD throughout the growing season and looking at remedial surgery techniques to manage BD in affected vines. The NWGIC team are also involved in the development of DNA-based diagnostic tools to detect and quantify GTD pathogens from the environment and grapevine plant materials. A better understanding of the epidemiology of GTD pathogens will allow targeted control methods, thereby reducing vineyard inputs. It will also provide growers with better forecasting and disease management options and improve vineyard performance.

Characterisation of the microbiome associated with grapevines and evaluation of potential biological controls

Team leader: A/Prof. Sandra Savocchia (NWGIC)

Team members:  Jennifer Niem (NWGIC PhD student), Dr. Regina Billones-Baaijens (NWGIC), Dr. Ben Stodart (SAWS)

Grapevine trunk diseases are considered a serious problem of grapevines worldwide. Eutypa dieback and Botryosphaeria dieback are among the top five priority diseases of the Australian wine grape industry. Current management of these diseases is through remedial surgery and fungicide treatments of pruning wounds. However, registered fungicides are limited and some only offer short term protection. Preliminary studies in our laboratory revealed some endophytic microorganisms including Pseudomonas spp. that inhibit the growth of some Eutypa and Botryosphaeria dieback pathogens.

This study aims to characterise the microbiome associated with grapevine wood and to assess their biocontrol potential including Pseudomonas spp. against grapevine trunk disease pathogens. The mechanisms of action involved in the control of the chosen trunk disease pathogens will be elucidated through laboratory assays and the use of molecular-based techniques targeting specific gene markers. Furthermore, the ability of the biocontrol agent to suppress trunk diseases in planta will also be evaluated.