Abstract
Water used for the irrigation of plants has the potential to act as both a source and a means of spread of plant pathogens, yet little research is conducted within this field. This study was conducted to increase our understanding of water-borne plant pathogens in an open irrigation system in Western Australia, particularly in the context of plant biosecurity. It was determined that various Oomycetes and fungal pathogens are present including Phytophthora (multiple spp.), Pythium (multiple spp.), Colletotrichum gloesporioides, Fusarium solani, Fusarium sp., Giberella sp., Leptosphaeria sp., Mortierella sp., Saprolegnia sp., Paecilomyces lilacinus, and various unknown species. The pathogenicity of some of these species has been confirmed on crops grown in the region. There are significant gaps in our knowledge of how these plant pathogens survive and spread in the irrigation system, and very limited information on their ability to cause disease when contaminated water is applied to crops in the region. This study has highlighted the need for new research on the epidemiology and pathogenicity of water-borne plant pathogens, to inform biosecurity risk assessments and develop mitigation strategies.