Etude de l’activait antifongique de l’extraits d’Atriplex halimus et Nerium oleander sur Alternaria solani.

Abstract

This study evaluates the antifungal efficacy of aqueous extracts of the plants Atriplex halimus and Nerium oleander against the fungus Alternaria solani, responsible for Alternaria blight, or Alternaria leaf spot, in tomatoes. Through in vitro tests, it aims to measure the inhibitory effect of these extracts on mycelial growth and sporulation of the pathogen, with the goal of proposing a natural alternative to conventional chemical treatments. The extraction yields of the plants studied were as follows: Atriplex halimus yielded 45.13%, while Nerium oleander yielded only 10%. The macroscopic appearance of the purified isolate revealed colonies with dense, dark gray to greenish-black mycelium, which was dense, branched, and septate, with a hyaline to light brown coloration. The conidiophores are erect, septate, simple or sometimes branched, bearing the conidia at their tips. The extract of Atriplex halimus L. exhibited a more pronounced inhibition of mycelial growth at low concentrations (3.125, 6.25, and 12.5 mg/ml) and a greater degree of inhibition at lower concentrations (3%, 6.25%, and 25%). The effect of the aqueous extract of Nerium oleander on the mycelial growth of Alternaria solani showed a significant inhibition of mycelial growth at all tested concentrations compared to the control. Conversely, all tested concentrations (3.13%, 6.25%, 12.50%, 25%, 50%, and 100%) showed a remarkable and almost total inhibition of mycelial growth. The aqueous extract of Nerium oleander exhibits potent and broad-spectrum antifungal activity against Alternaria solani.