Isolement et identification de la flore fongique associée au dépérissement du palmier dattier dans la région de Ghardaïa

Abstract

This study aims to isolate and identify the fungal groups associated with various symptoms of date palm decline in Ghardaïa region. Our work concerned four palm groves spread over two municipalities in the state of Ghardaïa, namely Sebseb and El Atteuf; covering the main varieties of date palm in the region, namely Ghars, Degla, Azerza, Adela, Bent khbala and Temjouhert, added to a male palm tree. The fungi have been isolated on PDA medium and identified on the macro and micromorphological level according to the identification keys found in the literature. The isolates obtained were evaluated for their pathogenicity on date palm seedlings to confirm the symptoms observed. The fungal strains obtained were also subjected to antagonism tests, against two strains of actinobacteria known for their antifungal potential (Saccharothrix lopnuriensis and Streptomyces griseorubens). The most affected variety was Degla, from which more than 26% of the fungi were isolated. The most frequent isolates belong to the two genera Fusarium and Alternaria with more than 15% each, followed by Scopulariopsis and Aspergillus with about 10% of the flora isolated. The isolate belonging to the genus Ulocladium is the most pathogenic with a necrosis length of more than 20 mm long. Fungal isolates showed variable sensitivity towards the two bacterial strains used in the antagonism test with a highest antifungal potential recorded for Saccharothrix lopnuriensis