Would you like wood or plastic? Bin material, sanitation treatments, and inoculum holding capacity impacts blue mold decay of stored apple fruit

Authors: Jurick, Wayne; CHOI, MEI-WAH - CORNELL UNIVERSITY; Gaskins, Verneta; PETER, KARI - PENNSYLVANIA STATE UNIVERSITY; COX, KERIK - CORNELL UNIVERSITY

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/7/2022
Publication Date: 4/21/2023
Citation: Jurick II, W.M., Choi, M., Gaskins, V.L., Peter, K.A., Cox, K.D. 2023. Would you like wood or plastic? Bin material, sanitation treatments, and inoculum holding capacity impacts blue mold decay of stored apple fruit. Plant Disease. 107:1177-1182. https://doi.org/10.1094/PDIS-05-22-1045-RE.
DOI: https://doi.org/10.1094/PDIS-05-22-1045-RE

Interpretive Summary: Blue mold is a devastating disease of apple fruit that is caused by a fungal pathogen during storage. The disease not only reduces the quality of fruit, but also contributes to the potential for mycotoxin contamination of processed apple fruit products. Fruit are picked into and stored in wooden and plastic bins. Since previous studies have shown that bins contain blue mold fungi, we sought to determine what bin type and cleaning treatment would result in less blue mold decay. Our study shows that wood bins can hold more spores than plastic, and that steam, and other chemical treatments are effective at reducing spores on the bin surfaces, manifesting in less spores to cause fruit rot. Hence, our results directly impact industry in selecting both optimal bin type and cleaning treatment to reduce decay. We envision that results from this study will also be used for other fungal rot pathogens and fruit and vegetable crops that are prone to storage decays.

Technical Abstract: Blue mold, caused primarily by Penicillium expansum, is a major postharvest disease of apples. It not only causes economic losses, but produces mycotoxins that contaminate processed fruit products, which contributes to food waste and loss. Previous research has shown that packing and storage bins harbor blue mold spores and that steam and hot water are efficient at reducing spore inoculum levels. However, a side-by-side comparison between wooden and plastic bins regarding their ability to harbor spores, the effect of chemical sanitation treatments on spore levels, and the impact of rinsate from treated bins on apple fruit decay have not been systematically investigated. Thus, we evaluated different sanitation treatments (chemical and physical) to reduce P. expansum inoculum levels on wooden and plastic bins that mimic production practices utilized in commercial packinghouses. We determined that wooden bins bound Penicillium expansum spores, 4 orders of magnitude lower, than plastic. When both bin types were treated with steam (wooden) or sterile hot water (plastic), Thyme Guard®, or Academy™ all treatments resulted in significantly (P < 0.05) lower spore levels compared to untreated controls. However, plastic bins retained lower numbers of spores after inoculation with contaminated rinsate, and would require much higher concentrations of P. expansum spores in rinsate to retain spores at level that would lead to decay on apple fruit. Overall, we conclusively demonstrated that plastic bins retain fewer spores than wooden bin and that both can be sanitized by a variety of physical or chemical treatments. Data presented provide impetus for producers to replace wooden bins with plastic, and that sanitizing bin surfaces will result in less available inoculum to incite blue mold decay on stored apple fruit.