As part of an investigation into the factors influencing the colonization of the rhizosphere and the root tissues of host plant, by
pathogenic and non-pathogenic strains of Fusarium oxysporum, the effect of a range of carbon (C) sources on the growth habits of
five strains of F. oxysporum were compared. The strains used were two F. oxysporum f. sp. lycopersici (Fol strains), two F. oxysporum
f. sp. radicis-lycopersici (Forl strains) pathogenic on tomato and strain Fo47, a non-pathogenic strain of F. oxysporum, currently used as
a biocontrol agent to reduce severity of fusarium diseases on several crops. Radial extension rates on solid media were measured
using soluble saccharides (glucose, xylose and D galacturonic acid), polysaccharides (carboxymethyl cellulose, xylan and pectin) and
soluble and insoluble extracts of tomato roots as C sources. Growth parameters were estimated by fitting a logistic equation to
biomass data recorded from liquid culture using the same C sources.
The strains were characterized by means of the pattern of radial extension rates on the various C sources, and the two Forl strains
were discriminated further from the other strains. The growth parameters were unique features of each F. oxysporum strains, whatever
the C source. The pathogenic strains did not exhibit particular abilities in degrading the cell wall components. It was concluded that
growth habits related to carbohydrate utilization are unique to each strain of F. oxysporum and that these traits are not related to
pathogenicity.