Postharvest management of potato tubers is essential for keeping up with consumer demands for fresh and processed potato products. The following studies were conducted for improved management of Michigan potato storages: (1) identification of storage rot pathogens present on tubers obtained from lower-peninsula Michigan, (2) efficacy of a potential management tool, SaniDate-5.0, on four major postharvest rots, and (3) varietal resistance in commercial and research potato germplasm. Twelve chip processing potatoes fields across six Michigan counties were included in the survey of tuber-associated abiotic and biotic factors. During the tuber survey, mechanical injuries (wounds and scrapes) (60-61%) and disease signs and symptoms (97%) were observed. Putative rot pathogens frequently isolated from tissue samples were species of Fusarium and Pythium. Out of 86 Fusarium isolates characterized to species, the most frequently collected species was F. oxysporum and the most virulent species on potato slices was F. graminearum. This differed from previous studies where F. sambucinum was the most virulent species causing dry rot. These findings suggest management and screening efforts should consider current population compositions for effective disease control. Next, an evaluation of the peroxyacetic acid sanitizer SaniDate-5.0 for control of four major rot diseases, Fusarium dry rot (FDR), bacterial soft rot (BSR), pink rot, and Pythium leak was performed in storage bins under commercial conditions. Across two years of repeated experiments, SaniDate5.0 did not significantly affect FDR in either year or pink rot in year two. Due to insufficient development of BSR and Pythium leak in these studies, inoculation protocols were optimized for future studies. Lastly, an assessment of varietal response to these four storage diseases was conducted on chipping, red-skinned, and yellow-flesh germplasm entries. Significant resistance reactions were observed on chipping varieties for FDR in 2020 and 2021, and for pink rot in 2020. Findings indicate that (1) Michigan pathogen isolates may cause variable results to those in other states and may provide valuable information to the screening process and (2) certain varieties may be more resistant to one or more storage diseases but also may vary widely in response across diseases. These screening efforts will further inform potato breeding and variety selection efforts to improve storage disease management. Combined, these studies have helped to identify prevalent diseases and evaluate potential chemical and varietal management strategies for disease impacting potato storages
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