ARS | Publication request: Evaluation of Contributed Lines for Resistance to Cercospora beticola, Causal Fungus of Cercospora Leaf Spot

Submitted to: Annual Beet Sugar Development Foundation Research Report
Publication Type: Research Notes
Publication Acceptance Date: May 15, 2009
Publication Date: June 1, 2009
Citation: Hanson, L.E., McGrath, J.M. 2009. Evaluation of Contributed Lines for Resistance to Cercospora beticola, Causal Fungus of Cercospora Leaf Spot CD-ROM]. 2009 Annual Beet Sugar Development Foundation Research Report. Denver, Colorado: Beet Sugar Development Foundation.

Technical Abstract: The need continues within the sugarbeet industry for objective evaluations of commercial hybrids for their reaction to Cercospora beticola, the cause of leaf spot in sugar beet. The cooperative Beet Sugar Development Foundation Cercospora leaf spot nursery was conducted at the Saginaw Valley Bean and Beet Farm in 2008. 166 commercial entries and checks were received and tested from three BSDF member companies in 2-row plots, replicated four times in a complete randomized block design. In addition, 226 breeding lines were tested in one- or two-row, three-replication plots from USDA collaborators from Salinas, CA and Ft. Collins, CO. East Lansing USDA entries included 239 open-pollinated accessions and 313 (partially) inbred lines. In addition, 61 Plant Introductions (PIs) from the USDA-ARS National Plant Germplasm System (NPGS) (Garden Beet, Sugar Beet, Leaf Beet, Fodder Beet, and wild beet) were evaluated. An artificially produced epiphytotic was produced. The moderate nighttime temperatures in the summer of 2008, combined with good moisture, contributed to a moderate leaf spot epidemic. Disease severity peaked by early September, after which regrowth started to outpace new disease development, so that disease ratings remained constant or decreased after that rating (trial mean 9 Sep 2008 = 4.2). At the 2 Sep 2008 rating means of the resistant and susceptible internal control for the entire nursery were 2.4 and 5.2 (scale of 0-10), respectively, across the nursery. In 2007 (27 Sep), these means were 1.8 and 5.3, respectively. Means of contributor lines in the entire nursery (including five additional tests) in 2008 ranged from 2.3 to 6.8. An analysis of variance (PROC GLM - SAS) on the disease indices (visual evaluation scores) determined that there were significant differences among entries (P<0.05) on all dates of evaluation.