Effects of inoculum density of R. solani AG 2-2IIIB and age of plant on root rot severity in sugar beet

Root rot of sugar beet (Beta vulgaris L.), caused by Rhizoctonia solani anastomosis group AG 2-2 IIIB is responsible for significant crop losses in North Dakota and Minnesota, USA. Understanding the association between plant age and inoculum density with disease sever­ity of sugar beet cultivars is...

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Main Authors: M.Z.R. Bhuiyan, Luis Del Río Mendoza, Dilip K. Lakshman, Aiming Qi, M.F.R. Khan
Format: Article
Language:English
Published: Polish Academy of Sciences 2025-03-01
Series:Journal of Plant Protection Research
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Online Access:https://journals.pan.pl/Content/134611/PDF/09_OA_JPPR_65_1_2068_Bhuiyan.pdf
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Summary:Root rot of sugar beet (Beta vulgaris L.), caused by Rhizoctonia solani anastomosis group AG 2-2 IIIB is responsible for significant crop losses in North Dakota and Minnesota, USA. Understanding the association between plant age and inoculum density with disease sever­ity of sugar beet cultivars is a prerequisite to properly screen for varietal resistance. There­fore, investigations were conducted to determine the responses of 4-, 6-, and 8-week-old plants in seven commercial sugar beet cultivars to inoculum densities of one, two, and three grains of R. solani-colonized barley in a greenhouse and with three corresponding levels of colonized barley, mycelial plugs, and sclerotia in field experiments. Under greenhouse con­ditions, disease severity was greatest before plants reached six weeks of age (p = 0.05). There was a positive linear relationship between the density of the inoculum and disease severity. All seven cultivars were equally susceptible (p > 0.05) to R. solani. Interactions between cul­tivars and plant age and between plant age and intensity of inoculum were not significant (p > 0.05). Field experiments showed that the density of inoculums was significant (p < 0.001), and the disease severity was highest in plants inoculated with three colonized barley seeds per plant compared to doses of other inoculum types.
ISSN:1427-4345
1899-007X