Field testing for seedling response to Rhizoctonia damping-off

Authors: CORDER, HOLLY - Michigan State University; MCGRATH, JON - Retired ARS Employee; Goodwill, Tom; Hanson, Linda

Submitted to: Journal of Sugar Beet Research
Publication Type: Abstract Only
Publication Acceptance Date: 1/1/2021
Publication Date: 2/28/2021
Citation: Corder, H.J., Mcgrath, J.M., Goodwill, T.R., Hanson, L.E. 2021. Field testing for seedling response to Rhizoctonia damping-off [abstract]. Journal of Sugar Beet Research. 58:96-97.

Interpretive Summary:

Technical Abstract: As well as causing Rhizoctonia root and crown rot, Rhizoctonia solani can cause stand loss in sugar beet seedlings as a damping-off. Previous research had shown adult plant resistance usually was not seen in seedlings, but testing in the greenhouse identified USDA germaplsm with seedling resistance. A nursery for seedling rhizoctonia has been developed to screen USDA germplasm and public releases. Original identification for seedling rhizoctonia resistance and recurrent selections for breeding lines with seedling Rhizoctonia resistance have been made using this nursery. Beets were inoculated with a lower rate of inoculum than used for adult beets, and water was applied to help the disease develop. Stand counts were taken early and throughout the year, and a final root rot rating conducted. Selections were made at the end of the season. Some germplasm have shown strong seedling resistance. It was previously understood that expressed resistance to Rhizoctonia happens in mature plants (transition at the 4-6 leaf stage), so observing reduced damage from R. solani at the seedling stage is a great step forward. Currently most screening has been to AG 2-2, but AG 4 has been tested as well, and varied response is present in germplasm.