Mold in, mold out: Harvest bins harbor viable inoculum that can be reduced using novel sanitation methods to manage blue mold decay of apples

Abstract

Postharvest diseases account for major economic losses worldwide, while also contributing to food waste and loss. Blue mold, caused by Penicillium expansum, is one of the most prevalent postharvest diseases of pome fruit. This necrotrophic fungal pathogen is mycotoxigenic and presents a danger to food safety via the production of patulin. In addition, fungicide resistance threatens blue mold management strategies, creating a need for the development of novel control strategies. The apple storage/processing industry uses wood and plastic harvest bins to harvest and store apples for weeks, months, and even up to 1 year. Although it has been hypothesized that apple harvest bins can serve as a viable inoculum source to incite decay, there is no experimental evidence that has conclusively demonstrated this concept. In this study, we report the presence of Penicillium spp. in apple storage bins (plastic) in the mid-Atlantic USA and developed small scale methods to test 1) if harvest bins can serve as a source of inoculum for blue mold decay and 2) evaluate novel bin sanitation methods as preventative and curative applications. We demonstrated that apple harvest bin materials can serve as a source of inoculum when in direct contact with wounded apples. Additionally, it was shown that UV-C irradiation, sodium hypochlorite, and 2-phenylethanol effectively reduce inoculum viability on plastic materials in a curative fashion. It is envisioned that these findings can aid in the development of large-scale bin sanitation strategies and their applications have great potential to impact a broader range of postharvest pathogens and stored commodities.