Tillage system and cropping sequence effects on common root rot of barley in eastern Saskatchewan
Fusarium head blight (FHB) in barley has been spreading on the Canadian Prairies for the last decade. Fusarium spp. causing FHB can also cause crown/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 percent 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-summerfallow (or summefallow-cereal) 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 summerfallow. Previous glyphosate applications were associated with lower C. sativus, and higher Fusarium spp., levels in barley grown under minimum till. This suggests changes in fungal communities; however, the mechanism(s) responsible for these changes in fungal levels are not known. Increased infection of ground/underground tissue by FHB pathogens might contribute to its development in succeeding cereal crops, therefore measures aimed at reducing root/crown infections by Fusarium spp. might also help reduce FHB development.
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