In a pot experiment, aldicarb (6 mg a.i. or 12 mg a.i./15 cm pot) was applied to P. penetrans infested soil which was either fallow or planted with a single raspberry (Rubus idaeus) host plant before, at the time of, or after treatment. Results showed that nematodes in the presence of a plant were more susceptible to aldicarb treatment with the nematicidal effect being greater the closer the treatment time was to planting. It is suggested that the presence of a host plant may affect the physiological state of Pratylenchus, thus influencing it sensitivity to aldicarb.