Introduction of the Endoparasitic Nematophagous Fungus Verticillium Balanoides Into White Clover (Trifolium Repens) by Its Host, Stem Nematode (Ditylenchus Dipsaci)

Abstract

White clover (Trifolium repens) was grown gnotobiotically in sand in pipette tips and inoculated at the base of plants with suspensions containing either the endoparasitic nematophagous fungus Verticillium balanoides, stem nematode (Ditylenchus dipsaci) or both fungus and stem nematode together. Two months after inoculation, foliage was excised, surface-sterilised and placed on water agar in Petri plates. In three experiments, V. balanoides was re-isolated from the majority of plants which received both nematode and fungus together and only in a single case from those receiving fungus alone. Results demonstrated that the fungus was carried along with D. dipsaci into foliar tissues of white clover and that the fungus infected and sporulated on D. dipsaci inside plant tissue. Some evidence is presented that conidia produced on dead nematodes can initiate new infections of nematodes within the plant.