By exposing potato plants in pots to a graded series of inocula of cysts of Heterodera rostochiensis, effects on the plant host have been investigated in terms of growth of shoots and tubers. High inocula reduce both criteria severely, but it appears that longer shoots and a larger weight of larger tubers are produced by plants exposed to a very low inoculum than by uninfested controls.

Effects on final eelworm population show that multiplication is highest at the lowest inocula but that the net highest population results from a moderate inoculum. Thus, the kind of inoculum which would stimulate crop yields, would also lead to a large eelworm population: highest potato yields were associated with an eelworm multiplication factor of about ten-fold.