IMPACT OF SUGARBEET ROOT DISEASES ON POSTHARVEST STORAGE

Authors: Campbell, Larry; Fugate, Karen

Submitted to: American Society of Sugarbeet Technologists
Publication Type: Proceedings
Publication Acceptance Date: 2/21/2003
Publication Date: 7/15/2003
Citation: CAMPBELL, L.G., KLOTZ, K.L. IMPACT OF SUGARBEET ROOT DISEASES ON POSTHARVEST STORAGE. PROCEEDINGS OF THE 1ST JOINT INTERNATIONAL INSTITUTE FOR BEET RESEARCH AND THE AMERICAN SOCIETY OF SUGAR BEET TECHNOLOGISTS CONGRESS. 2003. P.409-414.

Interpretive Summary: In recent years, the sugarbeet root diseases, Aphanomyces and rhizomania have become more prevalent throughout Minnesota and eastern North Dakota. Accompanying any increase in root disease in the field will be an increase in the proportion of diseased roots placed in storage piles. Information on the effects of root disease on initial quality and storability would, therefore, assist growers and agriculturalists when determining the disease severity that would justify not harvesting a field or if roots from diseased fields should be segregated and processed first. Respiration rate, extractable sugar per ton, and the formation of impurities that impede sugar extraction were determined in roots exhibiting varying degrees of Aphanomyces or rhizomania symptoms. Respiration rates of roots with moderate or severe Aphanomyces were substantially higher than respiration rates of healthy roots. The concentrations of the impurities were also elevated in severely rotted roots. The higher respiration rates of Aphanomyces infected roots are not only indicative of higher sugar loss but would also increase storage pile temperatures and increase sugar loss in adjacent healthy roots. Further sucrose loss would occur during the processing of rotted roots due to their increased concentrations impurities. Initial observations of the effects of rhizomania on sugarbeet root storage properties suggest that rhizomania is not nearly as detrimental to root storability as Aphanomyces, however, this indication is based on a single year¿s data. The impact of genetic resistance on storage properties appeared to be negligible as neither rhizomania nor Aphanomyces resistance was associated with higher respiration rates in the absence of disease.

Technical Abstract: In recent years, the sugarbeet (Beta vulgaris L.) root diseases, Aphanomyces and rhizomania (causal agents Aphanomyces cochlioides Drechal. and Beet Necrotic Yellow Vein Virus, respectively), have become more prevalent throughout Minnesota and eastern North Dakota. Accompanying any increase in root disease in the field will be an increase in the proportion of diseased roots placed in storage piles. Information on the effects of root disease on initial quality and storability would, therefore, assist growers and agriculturalists when determining the disease severity that would justify not harvesting a field or if roots from diseased fields should be segregated and processed first. Respiration rate, extractable sucrose per ton, and the formation of carbohydrate impurities were determined in roots exhibiting varying degrees of Aphanomyces or rhizomania symptoms. Respiration rates of roots with moderate or severe Aphanomyces were substantially higher than respiration rates of healthy roots. The concentrations of the invert sugars, glucose and fructose, were also elevated in severely rotted roots, although trisaccharide impurity concentrations were reduced. The higher respiration rates of Aphanomyces infected roots are not only indicative of higher sugar loss but would also increase storage pile temperatures and increase sugar loss in adjacent healthy roots. Further sucrose loss would occur during the processing of rotted roots due to their increased concentrations of invert sugars. Initial observations of the effects of rhizomania on sugarbeet root storage properties suggest that rhizomania is not nearly as detrimental to root storability as Aphanomyces, however, this indication is based on a single year¿s data. The impact of genetic resistance on storage properties appeared to be negligible as neither rhizomania nor Aphanomyces resistance was associated with higher respiration rates in the absence of disease.