Common root rot of barley in Saskatchewan and north-central Alberta

Abstract

Subcrown internode discoloration (SI discoloration), indicative of common root rot on barley, was evaluated across Saskatchewan in 1998–1999 (134 crops) and in north-central Alberta during 1994–1996 and 1998–2001 (263 crops). In Alberta, overall incidence of SI discoloration was higher in two-rowed than in six-rowed barley; however, there were no significant differences in mean SI discoloration severity between barley types in either province. In Saskatchewan, SI discoloration severity was lowest in the Brown Soil Zone. Recovery and identification of fungi from discolored samples collected in Saskatchewan revealed that Cochliobolus sativus was the most common species, followed by Fusarium spp., including the pathogens F. avenaceum and F. culmorum, the latter being the most prevalent overall. The last two species were present at similar levels in all soil zones, whereas F. graminearum was only isolated from discolored samples from the eastern region of Saskatchewan, but at low levels. In Saskatchewan, compared with results from a province-wide common root rot survey of wheat, Fusarium spp., including F. culmorum, were more widespread and frequent in barley. However, F. culmorum was absent or rarely isolated from infected spikes/kernels in Alberta and Saskatchewan, and overall, F. avenaceum was the dominant pathogen in fusarium head blight samples from the western Prairies. Environmental conditions in this region may be less suitable for spike infection by F. culmorum, or inoculum levels may be lower. Monitoring of fungal populations in crop residues in Saskatchewan showed that F. avenaceum was the most prevalent Fusarium pathogen in cereal and noncereal residues. Crop rotation with noncereal crops would likely decrease root and crown rot in barley caused by C. sativus and F. culmorum, but could increase inoculum of F. avenaceum and thus the probability of spike infections caused by this pathogen

Keywords:

• barley
• common root rot
• subcrown internode
• Fusarium
• F. graminearum
• F. avenaceum
• Cochliobolus sativus