Influence of cold-storage temperatures on strawberry leak caused by Rhizopus spp.

Abstract

Strawberry leak is a postharvest disease of cold-stored strawberry fruit. Between October 2007 and March 2009, the effect of temperature on growth and pathogenicity was tested for 39 isolates of Rhizopus and Mucor spp., the causal agents of strawberry leak. All isolates were grown on potato dextrose agar at target temperatures of 2-7°C. Most isolates grew at the lower temperatures tested, but temperature fluctuations in the incubators were also detected. A selection of the most cold-tolerant Rhizopus spp. isolates was used in a growth experiment on potato dextrose agar, sliced and whole fruit stored at 3°C. Fungal growth was monitored daily by removing samples at intervals and exposing them to 20°C for 2 h, before returning them to 3°C. Little difference was detected in overall growth patterns between numbers of interruptions, indicating that coldstorage only needs to be interrupted once for the fungus to be activated.