The effect of host plant on the control of Pratylenchus penetrans by aldicarb

SUMMARY Replicated pot tests were made to study the effect of a host plant, red raspberry (Rubus idaeus), on the control of Pratylenchus penetrans by aldicarb. Preliminary work indicated that nematodes from planted and fallowed soils could be distinguished by significantly different levels of lipid reserves in their bodies; and that the populations differed in their susceptibility to aldicarb. In pot tests aldicarb (6 mg. a. i. or 12 mg a. i. per 15‐cm pot) was added to P. penetrans infested soil which was either left fallow or planted with a single raspberry host plant before, at the time of, or after treatment. The results indicated that nematodes in the presence of a plant were more susceptible to aldicarb treatment than those in fallow soil. The results showed that the closer treatment‐time was to planting‐time the greater the nematicidal effect. It is suggested that P. penetrans may exist in different physiological states, active and quiescent, influenced by the presence of a host plant and that these two states differ in their susceptibility to the effects of aldicarb.