An Immunofluorescence Technique for Detecting Phytophthora cinnamomi Rands

Fluorescein-labelled antibodies were prepared for 'cell-wall' and 'soluble' antigens from P. cinnamomi. Those prepared against the cell wall fraction were superior for observing P. cinnamomi hyphae with the fluorescence microscope. Antibody-stained hyphae could be distinguished among hyphae from a wide range of fungal groups. P. cinnamomi hyphae could be seen on root surfaces and, although definition was hampered by plant tissue fluorescence, in infected roots. P. cinnamomi could not be detected in forest soil shown by baiting techniques to contain the pathogen, but was detected, and assayed quantitatively, in samples from laboratory soil cultures.