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United States Department of Agriculture

Agricultural Research Service

Title: Postharvest Storage Losses Associated with Aphanomyces Root Rot in Sugarbeet.

Authors
item Campbell, Larry
item Fugate, Karen

Submitted to: Journal of Sugarbeet Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 28, 2006
Publication Date: December 29, 2006
Citation: Campbell, L.G., Klotz, K.L. 2006. Postharvest Storage Losses Associated with Aphanomyces Root Rot in Sugarbeet. Journal of Sugarbeet Research. 43(4):113-128.

Interpretive Summary: Because of its persistence in the soil and the ineffectiveness of control measures, Aphanomyces root rot is one of the more problematic fungal root rots attacking sugarbeet. As the prevalence of Aphanomyces increases, the proportion of diseased roots placed in storage piles increases. This report provides guidance for determining the Aphanomyces root rot severity that would justify not harvesting a field or if roots from diseased fields should be processed early in the campaign. Roots from six commercial fields with chronic root rot problems were divided into groups based upon root rot severity. Prior to measuring storage respiration rate, sucrose concentration, and extractable sucrose concentration, a root rot index (0 = no rot to 100 = completely rotted) was determined for each sample. Regression analyses were used to characterize relationships among root rot index, postharvest respiration rate, and extractable sucrose losses during storage for 120 days. Below rot indices of 35, Aphanomyces had little, or no effect on respiration rate or extractable sucrose loss during storage. Sucrose losses associated with rot indices of 65 and 80 were 1.8 and 2.8 times those associated with a rot index of 35, respectively. Aphanomyces root rot has the potential to significantly increase losses during storage; however, field by Aphanomyces severity interactions and variability in the observed response patterns indicate that accurately predicting these losses prior to harvest will be difficult.

Technical Abstract: Because of its persistence in the soil and the ineffectiveness of control measures, Aphanomyces root rot (caused by Aphanomyces cochlioides Drechal.) is one of the more problematic fungal root rots attacking sugarbeet (Beta vulgaris L.). As the prevalence of Aphanomyces increases, the proportion of diseased roots placed in storage piles increases. This report provides guidance for determining the Aphanomyces root rot severity that would justify not harvesting a field or if roots from diseased fields should be processed early in the campaign. Roots from six commercial fields with chronic root rot problems were divided into groups based upon root rot severity. Prior to measuring storage respiration rate, sucrose concentration, and extractable sucrose concentration, a root rot index (0 = no rot to 100 = completely rotted) was determined for each sample. Regression analyses were used to characterize relationships among root rot index, postharvest respiration rate, and extractable sucrose losses during storage for 120 days. Below rot indices of 35, Aphanomyces had little, or no effect on respiration rate or extractable sucrose loss during storage. Sucrose losses associated with rot indices of 65 and 80 were 1.8 and 2.8 times those associated with a rot index of 35, respectively. Aphanomyces root rot has the potential to significantly increase losses during storage; however, field by Aphanomyces severity interactions and variability in the observed response patterns indicate that accurately predicting these losses prior to harvest will be difficult.

Last Modified: 7/22/2014
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