Fungal and Bacterial Species Associated with Storage Diseases in Sugar Beet from the Red River Valley of Minnesota and North Dakota

Sugar beet is a major source of consumable sugar in domestic and industrial applications in the United States. Sugar beet roots are stored for up to 280 days under cold ambient temperature conditions in the Red River Valley (RRV) of Minnesota and North Dakota. During this period, storage rots often develop that can reduce the sucrose content and processing quality of the roots. Knowledge of the pathogens responsible for this sucrose loss is limited but crucial for devising management strategies. This study was conducted to re-examine and identify storage pathogens infecting sugar beet roots in outdoor nonventilated piles in the RRV of Minnesota and North Dakota and characterize their prevalence and geographic distribution. In the first year of the study, more than 50 roots exhibiting storage rot were collected from an outdoor nonventilated pile (ONVP) in Minnesota. In successive years, 150 storage rot and damaged symptomatic roots were collected from five geographically distinct ONVPs with three located in Minnesota and two located in North Dakota. <i>Penicillium</i> spp., <i>Geotrichum candidum</i>, and <i>Mucor</i> spp. were common filamentous fungal species identified, whereas <i>Pichia membranifaciens</i> was the dominant yeast identified in both years of the study. <i>Leuconostoc mesenteroides</i> and <i>Gluconobacter cerinus</i> were common bacterial isolates in both years of the study. Most of the bacterial isolates obtained from ONVP-4 (North Dakota) (63%) and ONVP-5 (North Dakota) (99%) during the second year of the study were identified as <i>L. mesenteroides</i>. This study identified fungal and bacterial species associated with storage diseases of sugar beet roots in the RRV of Minnesota and North Dakota, which is pivotal for implementing management strategies to minimize postharvest sucrose losses during sugar beet storage.