A simulation study on managing plant diseases by systematically altering spatial positions of cultivar mixture components between seasons

A simulation study was conducted to investigate epidemic development of a race-specific pathogen in cultivar mixtures over six consecutive seasons where the spatial position of each mixture component was systematically altered between seasons. Results showed that, even for a relative large genotype unit area in a mixture, altering cultivar positions between seasons could, on average, increase disease suppression by a third over the corresponding mixture without position changes between seasons. Overall, the disease suppression achieved by mixtures with position change between seasons was close to that achieved by random mixtures. Greater redistribution distance of overwintered inoculum reduced the disease control efficacy achieved by change in the position of individual mixture components between seasons. It is therefore concluded that using mixtures with a relatively large genotype unit area together with systematic changes in the spatial positions of individual mixture components between seasons is a feasible option for integrated disease management.