Characterization and management of soil-borne pathogens on strawberry and resistance mechanisms against Fusarium oxysporum f.sp. fragariae / Xiangling Fang

[Truncated abstract] Strawberry (Fragaria × ananassa) is an economically important berry crop worldwide. However, commercial strawberry production is severely threatened by soil-borne fungal and oomycete pathogens and management is mainly reliant on chemical fumigation. In Australia, little is known about the characteristics of soil-borne fungal and oomycete pathogens on strawberry and how to manage them through non-chemical cultural practices or host resistance. Worldwide, the resistance mechanisms of strawberry against soil-borne pathogens remain poorly understood. This PhD project aimed to characterize soil-borne fungal and oomycete pathogens on strawberry in Western Australia (WA), to determine the potential of non-chemical cultural and host resistance management strategies, and to explore the resistance mechanisms of strawberry against the Fusarium wilt pathogen Fusarium oxysporum f.sp. fragariae. Commercial strawberry production in WA was severely compromised by crown and root diseases, and the associated fungi were F. oxysporum, Rhizoctonia spp., Cylindrocarpon destructans, Phoma exigua, Gnomonia fructicola and Macrophomina phaseolina, while associated oomycetes were Phytophthora cactorum and Pythium ultimum (Chapter 2). Among these, F. oxysporum was most frequently isolated from crowns at a frequency of 41%; Rhizoctonia spp. were most frequently isolated from roots at a frequency of 12%. F. oxysporum, Rhizoctonia spp. and M. phaseolina were found to be the most virulent pathogens on strawberry, and their virulence and consequent disease severity was influenced by the prevailing seasonal temperature (Chapter 3).