Treatment of soil in October 1963 with 60 lb (a.i.)/acre (67.3 kg/ha) quintozene or 400 lb/acre (448.4 kg/ha) D-D killed more than 95 per cent of the Longidorus elongatus present and largely prevented transmission of raspberry ringspot and tomato black ring viruses to ‘Red gauntlet’ strawberry planted in April 1964. The herbicide chloroxuron at 5 lb (a.i.)/acre (56 kg/ha) did not affect L. elongatus numbers but delayed infection of the strawberry plants by controlling weed sources of virus. Quintozene and D-D increased fruit yields four to six-fold in 1965 and nine to twelve-fold in 1966; chloroxuron caused only small increases, Quintozene persisted in the soil for several years but was not detected in strawberry fruit. In an experiment on virus-free soil, quintozene had no effect on ‘Talisman’ strawberry or ‘Malling Jewel’ raspberry, but adversely affected growth of ‘Lloyd George’ raspberry and sugar beet. L. elongatus migrated slowly through soil and congregated in the root zone of strawberry plants. Populations in untreated plots increased about two-fold per year. Eggs were laid from April to July.