ARS | Publication request: Seedling disease in Michigan

Submitted to: Research Results
Publication Type: Research Notes
Publication Acceptance Date: February 1, 2013
Publication Date: February 1, 2013
Citation: Hanson, L.E., Goodwill, T.R., McGrath, J.M. 2013. Seedling disease in Michigan. Research Education & Advisory Council (REACh) 2012 Research Results. p. 47.

Technical Abstract: Sugar beet seedlings (24 entries of a larger genetic population constructed to dissect Rhizoctonia disease reaction in sugar beet) were screened for their response to a highly virulent isolate of Rhizoctonia solani AG 2-2. Seedlings were grown to the two-leaf stage in the greenhouse, thinned to 15 plants per row, and inoculated with a preparation of R. solani in ground sterile barley, watered well, and maintained in the greenhouse for an additional three weeks. Plants were removed from the soil, washed gently in tap water, and rated for damping-off using a 0-5 scale, where 0=no symptoms and 5= dead plant with completely rotted root. Missing plants were rated as 5. A weighted Disease Index was calculated for each of the 24 entries based on the number of plants in each disease category relative to the total number of plants. Germplasm varied for response to AG-2-2, indicating this trait is segregating in this population. Previously, we discovered EL51 has resistance to seedling Rhizoctonia damping-off. The tested germplasm was derived from a cross between EL51 and a susceptible parent. Three of the tested lines had lower disease indices than EL51, suggesting improvement in seedling Rhizoctonia resistance is possible.