Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/11/2007
Publication Date: 2/19/2008
Citation: Strausbaugh, C.A., Gillen, A.M. 2008. Bacteria and yeast associated with sugar beet root rot at harvest in the Intermountain West. Plant Disease. 92:357-363. Interpretive Summary: Bacterial root rot is an important problem in sugar beets because of issues it causes in the field, storage, and factories. Bacterial rot in sugar beets has normally been attributed to Erwinia carotovora subsp. betavasculorum, but recent field observations and isolations indicate this situation may be changing. In the Intermountain West, a previously undescribed bacterial-like root rot complex was found to be occurring in sugar beets. Thus, a survey was conducted to establish the organisms responsible for this new rot complex. When only one organism was isolated from the wet rot in recently harvested roots, L. mesenteroides subsp. dextranicum was the most frequently isolated organism. This bacterium also caused the most rot when inoculated back into sugar beet root tissue in pathogenicity tests. The impact and circumstances responsible for this newly described rot complex in sugar beets is being investigated.
Technical Abstract: An undescribed bacterial-like root rot has been observed in sugar beets at harvest time in the Intermountain West. This root rot was observed during surveys of recently harvested sugar beets in 2004 and 2005. Microorganisms recovered from 287 roots fell into the following groups: lactic acid bacteria (41% of isolates), acetic acid bacteria (29%), enteric bacteria (17%), and yeast (13%). The lactic acid bacterial isolates included Leuconostoc mesenteroides subsp. dextranicum (80% of isolates) and Lactobacillus plantarum (20%). The acetic acid bacteria were dominated by Gluconobacter asaii (92% of isolates). Except for Erwinia carotovora subsp. betavasculorum, the bacteria and yeast isolates did not infect plants when inoculated into petioles. When inoculated onto sugar beet root slices, individually or in combination with other organisms, L. mesenteroides subsp. dextranicum led to the most rot. When only one organism was isolated from the wet rot in recently harvested roots, L. mesenteroides subsp. dextranicum was the most frequently isolated organism. The impact and circumstances responsible for this newly described rot complex in sugar beets is being investigated.