Sugar beet root storage properties are unaffected by Cercospora leaf spot

Authors: Fugate, Karen; KHAN, MOHAMED - North Dakota State University; Eide, John; HAKK, PETER - North Dakota State University; LAFTA, ABBAS - North Dakota State University

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/21/2022
Publication Date: 5/25/2023
Citation: Fugate, K.K., Khan, M.F., Eide, J.D., Hakk, P.C., Lafta, A.M. 2023. Sugar beet root storage properties are unaffected by Cercospora leaf spot. Plant Disease. 107(6):1649-1958. https://doi.org/10.1094/PDIS-09-22-2156-RE.
DOI: https://doi.org/10.1094/PDIS-09-22-2156-RE

Interpretive Summary: Cercospora leaf spot (CLS) is a sugarbeet disease found in most sugarbeet production regions due to the widespread distribution of the pathogen responsible for this disease and the inability of current management practices to adequately control disease development. Roots harvested from plants with CLS, therefore, are inevitably incorporated into the piles in which sugarbeet roots are stored prior to their processing, even though the effect of CLS on root deterioration during storage is largely unknown. Research was conducted to determine the extent that CLS affects sugar and processing quality losses during storage. Roots were harvested from plants with four levels of CLS severity in each of three production years, stored for up to 120 days, and the effect of CLS severity on sugar loss and quality deterioration was determined after 30, 90, and 120 days in storage. No effect on sugar loss or processing quality deterioration due to CLS was observed at any time during storage regardless of the severity of CLS disease symptoms. Therefore, CLS has no apparent effect on sugarbeet storage losses, and roots harvested from plants with CLS can be stored without additional or specialized precaution, regardless of CLS symptom severity.

Technical Abstract: Cercospora leaf spot (CLS; causal agent Cercospora beticola Sacc.) is endemic in most sugar beet production regions due to the widespread distribution of C. beticola and the inability of current management practices to provide complete control of the disease. Roots harvested from plants with CLS, therefore, are inevitably incorporated into sugar beet root storage piles, even though the effects of CLS on root storage properties are largely unknown. Research was conducted to determine the effects of CLS on storage properties including root respiration rate, sucrose loss, invert sugar accumulation, loss in recoverable sucrose yield, and changes in sucrose loss to molasses with respect to CLS disease severity and storage duration. Roots were obtained from plants with four levels of CLS severity in each of three production years, stored at 5°C and 95% relative humidity for up to 120 days, and evaluated for storage characteristics after 30, 90, and 120 days storage. No significant or repeatable effects of CLS on root respiration rate, sucrose loss, invert sugar accumulation, loss in recoverable sucrose yield, or change in sucrose loss to molasses were detected after 30, 90, or 120 days storage regardless of the severity of CLS disease symptoms. Therefore, no evidence was found that CLS accelerates sugar beet storage losses and it is concluded that roots harvested from plants with CLS can be stored without additional or specialized precaution, regardless of CLS symptom severity.