Fungal and bacterial species associated with storage diseases in sugar beet from the Red River Valley of Minnesota and North Dakota.

Abstract

Sugar beet is a major source of consumable sugar in domestic and industrial applications in the U.S. Sugar beet roots are stored for up to seven months under cold ambient temperature conditions in the Red River Valley (RRV) of Minnesota (MN) and North Dakota (ND). 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 open non-ventilated piles in the RRV of MN and ND and characterize their prevalence and geographic distribution. In the first year of the study, over 50 roots exhibiting storage rot were collected from an outdoor non-ventilated pile (ONVP) in MN. In the successive year, 150 storage rot and damaged symptomatic roots were collected from five geographically distinct ONVPs with three located in MN and two located in ND. Penicillium spp., Geotrichum candidum, and Mucor spp., were common filamentous fungal species identified, while Pichia membranifaciens was the dominant yeast identified in both years of the study. Leuconostoc mesenteroides and G. cerinus were common bacterial isolates in both years of the study. Most of the bacterial isolates obtained from ONVP-4 (ND) (63%) and ONVP-5 (ND) (99%) during the second year of the study were identified as L. mesenteroides. This study identified fungal and bacterial species associated with storage diseases of sugar beet roots in the RRV of MN and ND, which is pivotal for implementing management strategies to minimize postharvest sucrose losses during sugar beet storage.