The main focus of my research is on the effective management of economically important plant diseases in New Zealand using biological control methods.
My research investigates the use of naturally occurring micro-organisms or their metabolites to control soil-borne fungal pathogens such as Botrytis cinerea, Sclerotinia species, Sclerotium cepivorum, Pythium and Phytophthora species.
I have a particular interest in the study of the beneficial soil fungus Trichoderma. This fungus is naturally present in many diverse soil types and has a wide range of biological attributes which make it suitable for use in biological control (eg. properties such as plant growth promotion, antibiosis, parasitism, induced host plant resistance).
My research group has successfully commercialised four Trichoderma-based biocontrol products for the control of fruit and vegetable diseases.
Trichoderma studies range in diversity from molecular characterisation of biocontrol strains, production of molecular markers for ecological monitoring studies, laboratory and glass house evaluation of strains for biological control potential, determination of mechanisms of action of biocontrol agents through to commercial field evaluation of biocontrol agents and development of novel formulations
Steyaert, J.M., Weld, R.J., Stewart, A. 2010. Ambient pH intrinsically influences Trichoderma conidiation and colony morphology. Fungal Biology 114: 198-208.
Card, S.D., Walter, M., Jaspers, M.V., Sztejnberg A., Stewart, A. 2009. Targeted selection of antagonistic microorganisms for control of Botrytis cinerea of strawberry in New Zealand. Australasian Plant Pathology 38: 183-192.
Carpenter, M.A., Ridgway, H.J., Stringer, A.M., Hay, A.J., Stewart, A. 2008. Characterisation of a Trichoderma hamatum mono-oxygenase gene involved in antagonistic activity against fungal plant pathogens. Current Genetics 53: 193-205.
Rabeendran, N., Jones, E.E., Moot, D.J., Stewart, A. 2006. Biological control of Sclerotinia lettuce drop by Coniothyrium minitans and Trichoderma hamatum. Biological Control 39: 352-362.
Carpenter, M.A., Stewart, A., Ridgway, H.J. 2005. Identification of novel Trichoderma hamatum genes expressed during mycoparasitism using subtractive hybridisation. FEMS Microbiology Letters 251: 105-112.
McLean, K.L., Swaminathan, J., Frampton, C.M. Hunt, J.S., Ridgway, H.J., Stewart, A. 2005 Effect of formulation on the rhizosphere competence and biocontrol ability of Trichoderma atroviride C52. Plant Pathology 54: 212-218.