Alternaria alternata (Fr.) Keissler

5-day old
10-day old

COLONIES felt, zoned, grey (4B2) to olive brown (4F8), ca. 5 cm diam when 5-day old and covering the whole surface of potato dextrose agar (PDA) of a diameter of 10 cm when 10-day old.




CONIDIOPHORES (cp) usually single, straight or curved, 1-3-septate, up to 50 µm long, 3-6 µm wide, with one to many apical pores.


CONIDIA (c) in long, frequently branched chains, ovoid, obclavate, obpyriform, ellipsoidal, with a conspicuous basal pore, and with or without a short conical or cylindrical apical beak, pale brown to brown, smooth or warty, with 3-8 transverse septa and one to two longitudinal septa in the lower part, 18-63 x 7-18 µm.

SUBSTRATE AND DISTRIBUTION. Alternaria alternata commonly inhabits different plants and other substrates (Blaszkowski 1994 a, b; Blaszkowski and Piech 2002; Domsch et al. 1980; Piech and Blaszkowski 1993).

The fungus has a worldwide distribution (Domsch et al. 1980).

NOTES. Alternaria alternata is considered to be a saprotroph or a weak pathogen, especially of damaged plants (Holliday 1989). It is a common component of fungal populations associated with seeds of different plants (Blaszkowski 1994; Blaszkowski and Piech 2002; Holliday 1989; Piech and Blaszkowski 1993).


Blaszkowski J. 1994. The occurrence of Septoria nodorum Berk. and associated mycoflora in seeds of wheat cultivated in the Szczecin voivodeship. Acta Mycol. 29, 43-52.

Blaszkowski J. 1994. The influence of fungicides on the mycoflora of leaves of Triticum aestivum L. Acta Mycol. 29, 147-157.

Blaszkowski J., Piech M. 2002. Comparison of seed-borne fungal communities of naked and husked oats and barley. Phytopath. Pol. 24, 71-74.

Domsch K. H., Gams W., Anderson T. 1980. Compendium of soil fungi. Acad. Press. London-New York-Toronto-Sydney-San Francisco.

Holliday P. 1989. A dictionary of plant pathology. Cambridge University Press. Cambridge, New York, New Rochelle, Melbourne, Sydney.

Piech M., Blaszkowski J. 1993. The influence of the degree of reproduction on the mycoflora of winter XTriticosecale seeds. Bull. Pol. Ac. Sci. Biol. Sci. 41, 393-399.