Charcoal rot, caused by soil-borne fungal pathogen Macrophomina phaseolina (Tassi) Goidanich, is an important disease that affects strawberry cultivation in Australia. The pathogen has also been reported to cause significant plant losses worldwide and its emergence has been associated with the loss of the soil fumigant methyl bromide. Current fumigants are not able to eradicate the pathogen as effectively as methyl bromide.Management of the pathogen is also difficult due to its wide host range and ability to persist in the soil. The development of charcoal rot resistant genotypes is a major focus of the Australian Strawberry Breeding Program (ASBP). There are, however, several key gaps in the knowledge of charcoal rot of strawberry in Australia in order to breed for resistance.To address the lack of knowledge on host-pathogen interactions, a series of glasshouse experiments were conducted during 2015-2018 at the Maroochy Research Facility in Nambour, Australia. The first of the objectives was to develop an efficient and reliable inoculation method to be used for future disease screening. Two techniques were evaluated on two strawberry genotypes: inserting a M. phaseolina colonised-toothpick into the plant and drenching the potting media with a suspension of microsclerotia. A second objective was to identify genotypes with sources of resistance to M. phaseolina, where current and historical strawberry genotypes were screened. The third objective was to characterise M. phaseolina isolates for diversity and pathogenicity to strawberry, with the aggressiveness of thirty Australian M. phaseolina isolates investigated. Lastly, a genotype by isolate study was conducted to determine if there was a pathogenicity relationship between plant genotype and M. phaseolina isolate.M. phaseolina colonised-toothpicks were able to cause charcoal rot symptoms on two genotypes, and the likelihood of mortality at any given time was the same for both genotypes using this method. On the other hand, drenching plants with a M. phaseolina microsclerotia suspension found that one cultivar had a higher likelihood of mortality, suggesting inoculation by this method may better differentiate susceptibility between genotypes. For this reason, drenching potting media with a suspension of microsclerotia was the technique selected for subsequent pathogenicity assays for this study and for future breeding line screening.Studies on the strawberry genotype response to M. phaseolina showed the genotypes tested had varying degrees of resistance. Historical cultivars 'Earlibrite', 'Kabarla' and 'Phenomenal' were shown to be the most resistant to M. phaseolina. The cultivars 'Camarosa', 'Albion', Strawberry Festival', 'Rubygem', and 'Florida Radiance' were the least resistant.M. phaseolina isolates from Australia were non-specific as all isolates tested in this study were able to cause charcoal rot symptoms on strawberry. There were significant differences, however, in the pathogenicity of the thirty isolates of M. phaseolina assessed, which categorised in...