The influence of mixed cropping on the control of potato bacterial wilt (<i>Pseudomonas solanacearum</i>)

SUMMARY Experiments with bacterial wilt ( Pseudomonas solanacearum ) race 3 showed that the practice of intercropping potato with maize or haricot beans markedly reduced the incidence and rate of disease development in the potato crop. This reduction in disease 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 plant 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 markedly reduced the inoculum 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.