The agglutinating effect of five lectins having different sugar-binding specificities on the conidia of a variety of strains from eight Fusarium species was examined. Conidia of all the strains of F. solani and F. oxysporum were strongly agglutinated by concanavalin A and Helix pomatia agglutinin; D-mannose (and D-glucose) and N-acetyl-D-galactosamine inhibited the agglutination induced by concanavalin A and Helix pomatia agglutinin, respectively. Conidia of the other species of Fusarium examined (F. culmorum, F. sambucinum, F. graminearum, F. avenaceum, F. moniliforme and F. xylarioides) were not agglutinated by either lectin. No conidia from the Fusarium species were agglutinated by wheat-germ agglutinin, potato lectin and Ulex europaeus agglutinin-I. These results have provided some insight into the chemical nature of the outermost layer of Fusarium conidia and this information may be of taxonomic significance. [ABSTRACT FROM AUTHOR]