Submitted to: Annual Beet Sugar Development Foundation Research Report
Publication Type: Research Notes
Publication Acceptance Date: 5/15/2011
Publication Date: 7/15/2011
Citation: Hanson, L.E., Panella, L.W., Hill, A.L., Webb, K.M. 2011. Variability in Fusarium oxysporum from sugar beets in the United States – Final Report [CD-ROM]. 2011 Annual Beet Sugar Development Foundation Research Report. Denver Colorado: Beet Sugar Development Foundation.
Technical Abstract: Fusarium yellows can cause significant reduction in root yield, sucrose percentage and juice purity in affected sugar beets. Research in our laboratory and others on variability in Fusarium oxysporum associated with sugar beets demonstrated that isolates that are pathogenic on sugar beet can be highly variable. A better understanding of this variability is important in the efforts to test for Fusarium yellows resistance in beets and efforts to breed for resistance. Over the course of this study, more than 1000 Fusarium isolates have been collected. Fusarium oxysporum has been the most commonly isolated species, but four other species have been isolated every year of the study, and additional species have been found in some years and locations. These isolates are highly variable morphologically, genetically, and in virulence. Different species vary in frequency in different areas and years. A fairly consistent proportion of Fusarium oxysporum isolates from sugar beet roots have been pathogenic on sugar beet in a greenhouse screen. When isolates from seed stalk blight were compared, a higher percent were pathogenic, causing Fusarium yellows-type symptoms in greenhouse tests. Isolates from stalk blight also showed variability in virulence when used in root inoculations. Genetic sequencing revealed distinct groups of Fusarium pathogenic on sugar beet, with most groups containing highly virulent, moderately virulent, and non-pathogenic isolates. All five genetic regions sequenced gave similar results for the major groups with varying discrimination within the groups.