Distribution of Mucor piriformis, Rhizopus sexualis and Rhizopus stolonifer in relation to their spoilage of strawberries

Harris, J.E.; Dennis, C.

Transactions of the British Mycological Society 75(PART 3): 445-450


The Zygomycete species were isolated occasionally from flowers and immature fruits, but increased markedly on ripe fruits late in the season. In contrast, Botrytis cinerea was present at consistently high levels on strawberry flowers and fruits from the onset of flowering to the end of the harvesting season. This difference in distribution is due to the susceptibility of strawberry flowers and fruits at all stages of development to infection by Botrytis, whereas the Zygomycetes are only able to infect ripe and damaged white fruits. All species showed a greater potential to infect from a food base compared to a spore inoculum, and damaged fruits were invariably more susceptible to infection than undamaged fruits. The incidence of M. piriformis on flowers and fruits increased noticeably when rain splash occurred, indicating the presence of this species in the soil and debris. Low relative humidities (70-80%) favored formation of sporangiospores by R. sexualis and R. stolonifer growing on ripe strawberries, but at relative humidities above 90% R. sexualis formed large numbers of zygospores. M. piriformis produced sporangia at relative humidities of 70-100%.