VARIATION IN THE BANANA-WILT PATHOGEN, FUSARIUM OXYSPORUM f. CUBENSE

Abstract

The validity of many of the strains of Fusarium oxysporum f. cubense which have been reported rests primarily upon the cultural criteria used in their differentiation. An examination of certain of these cultural features, such as the presence or absence of odor, pigmentation, 'interaction', and colony morphology did not permit conclusive identification of strains. 'Finger printing' by means of chromatographic assay of exogenous amino acids, measurements of growth, and the production of fusaric acid by single-spore cultures of strains of the banana-wilt fungus confirmed initial observations that so-called clones, cultivars, varieties, and groups overlapped and were inseparable.Methods for the isolation of single microconidia from the lumen of individual host cells, a microculture technique which employed 0.5 ml of liquid medium, and the determination of 27 ninhydrin-reactive substances in culture filtrate are described.