Efficiency of pomegranate (Punica granatum L.) peels extract as a high potential natural tool towards Fusarium dry rot on potato tubers

• The methanol extract exhibited strong inhibition on mycelial growth of F. sambucinum.
• The methanol extract of peel completely suppressed spore germination of F. sambucinum.
• Chlorogenic acid (42.401 mg/g) was the main phenolic compound in the methanol extract.
• Morphological and ultrastructural alterations in Fusarium hyphae were observed by EM.
• The methanol extract caused a significant reduction in the potato dry rot development.

The efficacy of the methanol extract of pomegranate peels was evaluated for controlling the growth of Fusarium sambucinum in vitro and development of dry rot on potato tubers both in curative and preventive applications. The methanol extract exhibited 75.5% inhibition on mycelial growth of F. sambucinum and a complete inhibition on spore germination of the pathogen at the concentration of 20 mg/ml. Minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of the extract were determined to be 20 and 120 mg/ml, respectively. Twenty four individual phenolic compounds were identified and quantified in the extract using HPLC analysis, with the total phenol content as 104.6 mg GAE/g extract according to the Folin–Ciocalteu method. Scanning electron microscopy (SEM) observations revealed morphological modification in F. sambucinum hyphae including curling, twisting and collapse. Ultrastructural alterations were also observed using transmission electron microscopy (TEM) including cell empty cavity and the disintegration of cytoplasmic organelles. The methanol extract of peels caused a significant reduction in dry rot development on potato tubers inoculated with F. sambucinum in curative and preventive applications. The methanol extract of pomegranate peels could be applied as alternative natural products to synthetic fungicides in the biocontrol of dry rot on potato tubers.