Diseases under conservation tillage systems

The primary focus of this paper is on the effects of tillage and residue management on some diseases of cereal and oilseed crops in western Canada. In this region, reduced tillage lowers the impact of some root diseases but increases the impact of foliar diseases on cereals. Published data showing evidence of the effect of reduced tillage on diseases of oilseed crops is scarce. Diseases that were less economically important under higher tillage regimes may become more important with reduced tillage, but location and local environment largely influence which diseases will be present. Crop rotation is a key factor in residue management for disease control. Disease and yield loss were higher with monoculture than with more diverse rotations. Some crops may pose a greater risk to succeeding susceptible crops that share common disease problems, such as Sclerotinia on peas and canola. A well-balanced rotation should be at least 4 yr long with 50% of the interval devoted to cereals and the remainder divided among pulses, flax, other oilseed crops, or forages. The risk of most diseases may be lowered by understanding and managing the interactions between pathogens and crop residue through modifying local environmental conditions, crop rotation, limited tillage, and antagonistic mycoflora. Single disease control measures may be inadequate with reduced tillage; a holistic approach to crop systems and plant health management may provide the solution to disease problems.