Hard red spring and durum wheat cultivars were tested for susceptibility to common root rot (CRR) in 2000, 2001 and 2002 at the Williston

Research Extension Center in a field plot with high natural inncoulum of Cochliobolus sativus.  Incidence and severity of CRR were determined

for over 60 spring wheat cultivars and over 30 durum wheat cultivars.  There were 8 replicate blocks and an average of 33 plants from each

replicate of each line were individually scored for CRR using the subcrown internode index method.  In this method individual plants are grouped

into four disease categories corresponding to symptom expressions of <1%, 1-20%, 21-50% and >50% of the subcrown internode covered by

typical brown CRR lesions.  Samples for disease scoring were collected when plants were in the soft to mid-dough stage.  No cultivars were

immune to C. sativus infection, but highly significant varietal differences in CRR reaction were observed.  These trials have shown that

variations in resistance to CRR can be influenced by the environment, and ranked comparisons of genotypes may differ from Season to

season especially with those of intermediate reaction.                       

 

 

The following graphs show the 3 year average CRR percent severity for selected HRS wheat

and durum wheat varieties.  Note the severity scales start at 20% (durum) and 25% (HRSW)

- not zero.

 

 

¹ NDSU Williston Research Extension Center

² NDSU Department of Plant Pathology, Fargo, ND

³ NDSU Department of Plant Science, Fargo, ND