Studies on effects of crop rotation and tillage on blackleg disease (Leptosphaeria maculans) in canola (Brassica napus), dispersal patterns of L. maculans spores, and effects of temperature and relative humidity on infection of canola cotyledons

Leptosphaeria maculans (anamorph: Phoma lingam ), the causal agent of Blackleg of canola, is an important disease affecting the crop across western Canada. The disease could be significantly reduced when canola was rotated with wheat and flax, and was grown on tilled plots. Tillage showed a significant effect on decreasing the disease when it was performed with a single-crop rotation; however, it did not with a two-crop rotation. Survival of Blackleg pathogen on canola stubble significantly decreased within nine months. With increase of soil depth, viability of the pathogen significantly decreased. The pathogen had more difficulty in surviving in clay than in loam and sand. The optimum relative humidity and temperature were 70% and 18/20°C (night/day). (Abstract shortened by UMI.)...