Du Pont 1410 mixed into soil containing Longidorus elongatus transmitting raspberry ringspot (RRV) and tomato black ring (TVRV) viruses, or soil containing Xiphinema diversicaudatum transmitting arabis mosaic (AMV) and strawberry latent ringspot (SLRV) viruses, to give nematicide concentrations of 50, 25 or 12.5 ppm, reduced nematode numbers and largely prevented virus transmission to seedlings of Cucumis sativus (by Xiphinema ) and Chenopodium quinoa (by Longidorus) after 5 weeks at 16 deg or 24 deg C. 5 weeks after 2 foliar sprays (with 6 days in between) of Du Pont 1410 at 4,500 ppm L. elongatus and X. diversicaudatum were reduced in pots of C. sativus containing either nematode, indicating the translocation of nematicidal material to the root region. However, there was slight virus transmission in X. diversicaudatum soil. 4 days after a series of 4 such foliar sprays (given at 4-day intervals) of C. sativus in sterilized nematode-free soil, virus transmission was prevented when C. sativus was grown in this soil mixed 1:1 with soil containing either of the nematodes. This indicates the production of a nematicidal root exudate which may be more persistent than the parent material.