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Is fungicide thermo-nebulization the solution for managing postharvest diseases?

Achour Amiri: Washington State University

<div>For decades, fungicides have been applied through drenching at harvest or applied in wax on the packing line to protect pome fruit from pathogen infections. Drenching may provide the fungicide right to the fruit surface to protect wounds occurring during harvest and transportation. However, cross-contaminations during the drench and generation of fungicide waste can limit its efficiency. Thermo-nebulization (TNB), i.e. thermo-fogging or thermo-aerosolization, is a new concept for applying fungicides postharvest and its efficacy has not been investigated. Trials were conducted at 3 commercial packinghouses in the fall of 2016 and 2017, including artificially-wounded fruit inoculated with <em>Penicillium expansum</em>, <em>Botrytis cinerea</em>, and <em>Neofabraea perennans </em>as well as naturally infected fruit. Fruit were treated with thiabendazole, pyrimethanil, or fludioxonil, applied trough drench or TNB, and stored in controlled atmospheres for 5 to 7 months. Disease incidence and severity were determined and fungicide residue levels on fruit were evaluated. Early results suggest that drench provide a higher efficacy than TNB against the three pathogens inoculated artificially. TNB resulted in higher residue levels than drenching and in room and bin-variability was observed in fungicide residue levels following TNB. Our findings suggest that drenching may be more effective than TNB applications, which on the other hand, can mitigate some food safety and environmental risks in the future.</div>