Submitted to: Agronomy Society of America, Crop Science Society of America, Soil Science Society of America Meeting
Publication Type: Abstract Only
Publication Acceptance Date: July 23, 2003
Publication Date: September 2, 2003
Citation: Panella, L.W., Hanson, L.E., West, M.S. 2003. Evaluation of disease resistance in a field nursery. Agronomy Society of America, Crop Science Society of America, Soil Science Society of America Meeting. Technical Abstract: Cercospora leaf spot and rhizoctonia root- or crown-rot are important sugarbeet diseases world wide. A natural epiphytotic does not produce a consistent, uniform disease pressure, therefore the USDA-ARS program in Fort Collins, CO, develops an artificial epiphytotic annually. We examined grouping lines based on field performance using 10 Cercospora-resistant germplasm and 40 Rhizoctonia-resistant germplasm with susceptible checks grown over 3 years. Disease indices (DIs) were determined, and data analyzed by PROC MIXED. Means were separated with Dunnett's one-tailed t test, testing if any entry was significantly (p=0.05) less than the susceptible control (more resistant) or significantly greater than resistant check (more susceptible). Two of the 41 Rhizoctonia-resistant germplasm were not significantly different from a susceptible check, 10 were as resistant as the resistant check, and 16 were moderately resistant. All cercospora-resistant germplasm were significantly better than the susceptible check, and 16 were moderately resistant. All Cercospora-resistant germplasm were significantly better than the susceptible check and 5 were significantly more susceptible than the resistant check. A variable clustering technique, (PROC VARCLUS) was used with each block of Cercospora DIs as a multivariate observation and each line a separate variable. The variables were clustered according to their similarity of scores, and 3 clusters specified. One germplasm was grouped with the resistant check, 4 were grouped with the susceptible, and 4 more were grouped as moderately resistant.