Residue burning and tillage effects on diseases and yield of barley (Hordeum vulgare) and canola (Brassica napus)

Crop residue is often managed by tillage or burning in western Canada. This study was conducted to test the hypothesis that burning crop residues reduces the severity of barley (Hordeum vulgare L.) and canola (Brassica napus L.) diseases, and increases seed or grain yield or quality. Experiments were conducted at 2 sites, a Gray Luvisol (Typic Cryoboralf) and a Dark Gray Luvisol (Mollic Cryboralf) over 5 years in northeast Saskatchewan, Canada, with treatments of: zero (ZT) and conventional (CT) tillage, and burning (B) or no burning (NB) of previous crop residue. At each site, an experiment for barley and another for canola was established in a 2-year barley–canola rotation. Severity of leaf spotting diseases of barley, mainly net blotch [Pyrenophora teres Drechsler], and incidence of sclerotinia stem rot [Sclerotinia sclerotiorum (Lib.) de Bary] of canola were sometimes greater in the B treatment than the NB. Leaf spot severity of barley was usually slightly reduced under CT compared with ZT, but regardless of severity, barley yields were either similar, or more often higher under ZT than CT (337–766 kg ha−1 or 11–57%). There were occasionally effects of B on barley yield, but results were inconsistent and sometimes depended on tillage system. Canola yield tended to be greater under ZT than CT (141–233 kg ha−1 or 9–44%), but the effect of B was inconsistent. Tillage system had the greatest impact on crop yields with higher yield more often under ZT than CT, most likely as a result of improved soil moisture under the ZT system. We conclude that use of fire to manage diseases of barley and canola is ineffective.