Intercropping for disease suppression

Background

Intercropping has many ecological benefits, including disease reduction. Although substantial evidence has been gathered over the past decades confirming the disease suppressive potential of intercropping, the question of how exactly more diverse systems can reduce diseases is not completely clear. The aim of this thesis is to study the effect of intercropping on disease reduction, and to improve our understanding of the specific workings of the disease suppressive mechanisms at play, using the potato late blight pathosystem as a tangible example.

Project description

The aim of this research is to study the effect of intercropping on disease suppression, and to improve our understanding of the specific workings of disease-suppressive mechanisms at play. Different methods were used; a meta-analysis was conducted to study the effect of intercropping on plant diseases, in order to find generic patterns across pathosystems. Subsequently, field experiments were conducted to focus on the effect of (strip)intercropping on potato late blight specifically, and unraveling to which different factors and mechanisms contribute to disease reduction in this pathosystem.

Results

• The average disease suppression of intercrops across pathosystems appeared to be independent of pathogen type (fungal, bacterial, or viral), pathogen characteristics, host density, intercrop design, and relatedness between focal host and companion crop. (meta-analysis)
• Strip cropping lowered late blight severity compared to potato monoculture. (field experiment)
• Strip cropping with both grass or maize reduced potato late blight severity.
• Grass as a companion was slightly more effective than maize for disease suppression.
• Microclimate modifications conferred by the companion crops, significantly contributed to the observed disease suppression.