Macrophomina phaseolina and Its Association with Strawberry Crown Rot in Australia

Macrophomina phaseolina has been associated with serious crown rot losses in Australian strawberries in recent years. The fungus produces microsclerotia on standard media and dark ostiolate pycnidia when grown on sterile strawberry crown tissue and wooden toothpicks. Experiments in a glasshouse to confirm Koch's postulates indicated the pathogenicity of the fungus in two cultivars, Sugarbaby and Treasure. In the field, a range of soil fumigants killed buried microsclerotia, but only a mixture of methyl bromide and chloropicrin (50:50) eradicated the fungus in infected crowns buried in the soil. This work and worldwide reports suggest that this pathogen may become more important in strawberries in the absence of methyl bromide.