Submitted to: Workshop Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 9/7/2011
Publication Date: 9/7/2011
Citation: Hanson, L.E. 2011. Fusarium seed stalk blight and rot in sugar beet. International Institute for Beet Research Workshop Proceedings. Available: http://www.iirb.org/media/hanson_fusarium_joint_pests_diseases_seed_quality_2011fusarium.pdf
Technical Abstract: Fusarium can cause damage to seed stalks that can cause reductions or complete loss of seed production. Fusarium oxysporum has been the reported cause of seed stalk blight, which is characterized by vascular discoloration. We sampled diseased seed stalks and examined isolates for their pathogenicity and virulence on sugar beet seed stalks in greenhouse tests. Seed stalk tissue of sugar beet germplasm that had previosly been determined to be susceptible to Fusarium oxysporum, as well as germplasm with varying response to F. oxysporum was inoculated using a hanging-drop inoculation method. Confirmation of pathogenicity was done by inoculating beets that had been induced to bolt by dipping the root in a fungal spore suspension. Fusarium oxysporum was the most commonly isolated species from seed stalks, but three other species also were isolated from stalk lesions, and all three caused rot of seed stalk when inoculated into seed stalks. While F. oxysporum isolates caused dark discoloration of the vascular tissue first and rapidly spread up the seed stalk, isolates of the other three species caused dark discoloraion and rot of the cortical tissue first. Isolates of F. solani caused small rot lesions that weakened the seed stalk. All germplam tested showed similar responses to the F. solani isolates. Sugar beet germplasm varied in the severity of disease caused by F. oxysporum and the other two Fusarium species. This indicates that there is a potential to select sugar beet for tolerance to stalk rot caused by Fusarium species in addition to the resistance already identified to stalk blight caused by F. oxysporum.