Morphological and molecular identification of /Fusarium oxysporum/ f. sp. /lycopersici /associated with /Olea europaea/ var. /sylvestris/ decline phenomenon in Tunisia.

Decline phenomena and mortality of Olea europaea var. sylvestris (oleaster) have been reported throughout the forest of Henchir Kort (northeastern of Tunisia). The affected plants show progressive dieback of shoots, twig blight symptoms and trunk canker. The fungi appear to have the most significant potential threat to the disease. However, it has been less well-studied in Tunisia. A survey on the causal agents of O. europeae decline attacked twigs with symptoms of wilting and vascular necrosis were collected. The causal agent of the syndrome was identified as Fusarium oxysporum f. sp. lycopersici based on morphological characteristics and molecular identification performed by sequencing the ITS region of the ribosomal DNA. Fusarium species are among the most aggressive telluric fungi, causing diebacks of many plant species, especially on Olea europaea. To the best of our knowledge, this is the first record on the occurrence of Fusarium oxysporum f. sp. lycopersici on O. europaea in the word and in Tunisia.