IDENTIFICATION OF THE MAIN PATHOGENIC FUNGUS OF ROOT ROT OF DATE PALM OFFSHOOTS (PHOENIX DICTYLIFERA L.), AND THE ANTAGONISTIC EFFECT OF TRICHODERMA HARZIANUM IN VITRO

Abstract

Root rot is a significant underground disease in date palms (Phoenix dactylifera L.) caused by pathogenic soil-borne fungus Fusarium oxysporum. Polymerase chain reaction (PCR) amplification was performed, followed by analysis of the sequences of nitrogen bases of the products using the program BLAST (Basic Local Alignment Search Tool). The results revealed that most pathogenic isolates were belonging to F. oxysporum, F. proliferatum S1, F. proliferatum S2, and F. fujikuroi. The selected isolates of Fusarium spp. were sequenced. The result of a pathogenicity assay shows that all the assayed isolated fungi were pathogenic to date palm plantlets at different percentages, and the main causative pathogenic fungus was F. oxysporum with disease severity (DS) of 96% and disease incidence (DI) of 96.6%. An attempt was made to find the most appropriate bioagents that can protect date palm offshoots (P. dactylfera L.) from certain soil-borne fungal diseases. The antifungal efficacy of Trichoderma harzianum was tested in vitro, where it inhibited mycelial radial growth of F. oxysporum by 87% on PDA medium. The results showed there was no reduction in mycelial growth of T. harzianum at all the different concentrations of NaCl tested under in vitro growth conditions compared with control concentrations (0 dSm).