Repeated annual growing of the same crops was compared with the growing of alternating crops in a 4-year study of the influence of cropping on the population dynamics of L. elongatus in Scotland. The crops involved were grass (Lolium spp.), pea, swede, potato, carrot and barley and there was also a fallow treatment. Only the grass crop was found to be a host for L. elongatus. The significant decrease in nematode numbers under all the other crops was mainly attributable to a decrease in the numbers of larval stages. It is suggested that L. elongatus is unable to reproduce on these crops under agricultural conditions.