ARS | Publication request: Postharvest Rhizopus rot on sugar beet

Submitted to: American Society of Sugar Beet Technologists
Publication Type: Abstract Only
Publication Acceptance Date: December 16, 2010
Publication Date: March 2, 2011
Citation: Hanson, L.E., Cho, I., Nagendran, S. 2011. Postharvest Rhizopus rot on sugar beet. American Society of Sugar Beet Technologists. In: Proceedings of the American Society of Sugar Beet Technologists. 36th Biennial Meeting, March 2-5, 2011, Albuquerque, New Mexico. 2011 CDROM.

Technical Abstract: Rhizopus species have been reported as a minor post-harvest rot on sugar beet, particularly under temperatures above 5 deg C. In 2010, Rhizopus was isolated from beets collected from Michigan storage piles in February at a low frequency. However, recent evidence from Michigan has found a high incidence of Rhizopus infecting beets with Rhizoctonia root rot. This has the potential to provide inoculum for post-harvest rot and could increase prevalence of this pathogen in storage. Research was undertaken to improve our understanding of Rhizopus as a post-harvest rot of sugar beet. Beets of variety USH20 were inoculated with isolates of Rhizopus stolonifer and Rhizopus oryzae and incubated optimal conditions for Rhizopus growth under high humidity. Both species were able to cause extensive rot of beet tissue on beets that had been stored at 4 deg C for 2 months or more. Little damage was observed on beets that had been stored for 1, 2, or 3 weeks at 4 deg C. When tested, no significant differences were found in the amount of rot produced over three days on four different sugar beet germplasm, but individual Rhizopus isolates varied in the amount of damage caused on sugar beet variety USH20. Isolates of R. oryzae generally caused more rot than isolates of R. stolonifer. When tested on cherry or strawberry, no significant difference in rotting was observed for these species. Further tests at lower temperatures and with additional beet germplasm are ongoing.