Survey of Defects and Diseases, Including Virulent Fusarium Species, Associated with Chipping Potatoes at Harvest and Post-Storage

Abstract

The U.S. consumption of potatoes spans fresh, frozen, chipping, dehydrated, and canned potato sectors. However, more than 50% of potato products are consumed after processing. Michigan produces potatoes for chip production, which are in demand year-round, as well as seed tubers that must be stored over the winter for the following season. To minimize damage and preserve tuber quality, pathogens present in storage must be properly identified so management strategies can be implemented to prevent economically damaging disease development. In this study, defects and diseases entering and persisting in Michigan chipping potato storages were evaluated via sampling of 12 fields across five counties. Tubers were visually assessed for symptoms and signs of disease, and putative pathogens were isolated from internal and external tuber tissues. Representative Fusarium species were further characterized, and significant variability ( P < 0.0001) was detected in virulence assessed on ‘Lamoka’ tuber slices. Overall, Fusarium dry rot, Pythium leak, and pink rot were prevalent postharvest diseases in Michigan. Despite low frequencies of isolation, incidence observations also suggest that tuber soft rot should be considered in potato storage disease management. Differing from previous surveys, F. graminearum was characterized as a highly virulent species associated with potato tubers in Michigan and warrants further investigation. Future dry rot research, such as potato breeding screening or management studies, should consider using representatively virulent Fusarium spp. or F. graminearum isolates. Potential shifts in pathogen species compositions over time further warrant continued monitoring and reassessment of screening protocols.