After studies (2006-2009) of the states of fading of citrus fruits in the Mitidja (Algeria), we noted a troubling epidemic evolution in some orchards where the death rates reached proportions of 5 to 10%. The symptomatologic diagnosis indicates the presence of a strong likeness between the different biotic reasons possible without the presence of symptoms typical and/or of revealing signs of the known diseases (bacteria and virus). The diagnosis of laboratory confirmed their absence. The isolations achieved from the roots and soil put often in evidence the presence of Fusarium flora dominated by Fusarium solani and Fusarium oxysporum species. The implication of these species is joined to the pedological features and to the technical practices, notably the irrigation.
