2002 Uniform Regional Scab Nursery for Spring Wheat Parents
 
 
 
         Coordinator:  David F. Garvin
                   USDA-ARS, Plant Science Research Unit
                   411 Borlaug Hall, University of Minnesota
                   1991 Upper Buford Circle, St. Paul, MN 55108
         Report prepared by: David F. Garvin and Leanne
 Matthiesen
 
 
      The Uniform Regional Scab Nursery was grown for the eighth
 year in 2002.  Six locations were included in the nursery,
 including Brookings, SD; St. Paul and Crookston, MN; Prosper and
 Langdon, ND; and Glenlea, MB, Canada.  Data were obtained from
 all locations for inclusion in this report.  A total of 44
 entries were included in the nursery in 2002.  This included the
 resistant checks 2375, BacUp, and ND2710, and the susceptible
 checks Wheaton and Oslo.  The other 39 entries were contributed
 by the University of Minnesota, North Dakota State University,
 South Dakota State University, Agriculture and Agri-Food Canada,
 Western Plant Breeders, and Agripro.  Seven of these 39 entries
 were durums.  Five genotypes from South Dakota (PI entries)
 represent possible new sources of scab resistance and were
 included in the nursery.
      The field data collected at each location varied, but a core
 set of traits evaluated on entries at 5 locations or more
 included incidence of scab (expressed as % infected heads),
 disease severity (expressed as % of diseased florets on infected
 heads), disease index (incidence x severity/100), and visual
 scabby kernel ratings (VSK,  tombstone), expressed as % kernels
 in a grain sample.  Additionally, 4 locations provided grain
 deoxynivalenol (DON) concentrations, expressed as ppm in a grain
 sample.  Other trait data were gathered at the different
 locations, and are presented in the individual location tables.
 A final table reporting overall entry means for parameters across
 locations is included after individual location data tables.
 Further, relative rankings of entries for disease incidence,
 disease severity, disease index, VSK and DON are provided as new
 tables in this year's report.
      Disease pressure varied from location to location, with mean
 disease incidence ranging from a low of 52.3% for Langdon to a
 high of 99.8% at Brookings.  Mean location severities ranged from
 7.7% at Langdon to 67.4% at Prosper, while mean disease index
 ranged from 4.8% at Langdon to 46.9% at Brookings.  Mean VSK
 ranged from 8% at Crookston to 46.5% at Prosper.  It should be
 noted that the nursery locations in Minnesota do not record VSK
 ratings if they exceed 50%, and thus the VSK means at these
 locations will be biased towards values lower than the true
 means.  Mean location DON concentrations ranged from 3.5 ppm at
 Crookston to 36.9 ppm at Prosper.
      Correlation coefficients were calculated between disease
 index, VSK, and DON, using overall means calculated from the
 locations at which each of these parameters was measured.  The
 correlations among these parameters were in each instance
 positive and significant.  The correlation between disease index
 and VSK (4 locations) was 0.91, while disease index and DON (3
 locations) exhibited a correlation of 0.85.  Lastly, VSK and DON
 (3 locations) also exhibited a significant correlation (0.77).