Impacts of Crop Production Factors on Common Root Rot of Barley in Eastern Saskatchewan

Fusarium head blight (FHB) in barley (Hordeum vulgare L.) has been spreading on the Canadian Prairies for the last decade. Fusarium spp. causing FHB can also cause crown and root rot of cereal crops. It is therefore of interest to determine the impact of agronomic practices on fungal populations associated with root rot of barley. From 1999 to 2001, 137 barley crops were sampled in eastern Saskatchewan for severity of subcrown internode discoloration and percentage isolation of fungi. Cochliobolus sativus was the most commonly isolated fungus, whereas the most commonly isolated Fusarium spp. included the FHB pathogens F. avenaceum, F. culmorum, and F. graminearum. Discoloration caused by C. sativus was favored by conventional-till, whereas Fusarium spp. increased in reduced tillage systems. Barley grown after a cereal-summer fallow sequence under conventional- or minimum-till had increased levels of C. sativus. Fusarium spp. were most affected by the previously grown crop(s); they were more common in barley grown after a noncereal than a cereal, and after two noncereals, or a noncereal alternated with summer fallow. Previous glyphosate applications were associated with lower C. sativus and higher Fusarium spp. levels in barley grown under minimum-till management. This suggests changes in fungal communities; however, the mechanism(s) responsible for these changes in fungal levels are not known. Increased infection of ground and underground tissue by FHB pathogens may contribute to its development in succeeding cereal crops. Therefore, measures aimed at reducing root and crown infections by Fusarium spp. may also help reduce FHB development.