The influence of mixed cropping on the control of potato bacterial wilt (Pseudomonas solanacearum).
Experiments with P. solanacearum race 3 showed that intercropping potato with maize or haricot beans (Phaseolus vulgaris) markedly reduced the incidence and rate of disease development in the potato crop. This was considered to be an effect of the increased distances between individual potato plants, their spatial arrangement and the presence between potato plants of root systems of other species, all of which resulted in a reduction in plant-to-plant transmission, via the roots. The lower potato plant population associated with intercropping resulted in a slower rate of inoculum build-up in the soil and the presence of an intercrop further reduced build-up. Where farmers retain tubers for seed, but where roguing of diseased plants is not practised, the isolation of plants through intercropping was considered to facilitate an efficient selection of healthy tubers.