Reactions of hard red spring wheat to common root rot under field conditions of Northern United States of America

Common root rot (CRR), primarily caused by Cochliobolus sativus, is one of the important soil borne diseases of wheat (Triticum aestivum L). To gain information about resistance of hard red spring wheat (HRSW) to the disease, forty HRSW cultivars and advanced breeding lines were grown and evaluated in a completely randomized block design for reaction to CRR from 2000 to 2002 in a field plot with high natural inoculum of C. sativus at Williston, ND. Plant root samples during the soft to mid-dough stage were collected and CRR incidences and severities were scored using the subcrown internode index method. Disease severities (DS) varied from 24-61% in 2000 and 2002, but were relatively low in 2001 (19-40%). None of the wheat cultivars was immune to CRR. The genotypes Canon, Forge, Dandy, Ember, Butte 86, Oxen, AC Barrie, Parshall, and 2371 had higher DS (> 45%) and exhibited susceptible disease reactions. However, the genotypes ND 722, AC Cadillac, HJ 98, Argent and Scholar had lower levels of DS throughout the study period, and these were better than, or similar to Amidon, the resistant check. The HRSW cultivars with consistent resistance to CRR during the three year evaluation could be valuable resistance sources for use in breeding programs.