Effect of a Culture Filtrate From Fusariuma Venaceum On the Penetration of Heterodera Daverti Into Roots of Trifolium Subterraneum

Roots of seedlings of Trifolium subterraneum exposed for 7.5 min to a culture filtrate of Fusarium avenaceum were penetrated by juveniles of Heterodera daverti to a greater extent than roots not so exposed. Exposure times greater than 30 min decreased penetration. Fusaric acid was not detected when the culture filtrate was examined by paper chromatography. Pectinmethylesterase (PME) was produced by the fungus. Roots of T. subterraneum showed an increased ion efflux when exposed for two hours to the culture filtrate with or without PME. H. daverti juveniles were attracted to root diffusates obtained after roots were exposed to culture filtrate.