The genus Marasmius is distributed worldwide, along with a precise identification of this fungus as a pathogen on the Imperata cylindrical plant, although its bioactive role is not well understood. The current work was designed to examine the population of Marasmius palmivorus and its antagonistic patterns. Sequencing the ITS genetic region of this fungus occurs through verifying the cladistics nature, and taxonomic validity, in addition to studying the antagonistic potential of this fungus. M. palmivorus (MG717877.1) was recorded in this plant, which represents a new finding in Iraq mycobiota. Data from the sequence alignment were used to plot a phylogenetic tree, using the Neighbor-Joining method (NJ) in molecular evolutionary genetics analysis based on Mega 7. Phylogenetic trees show a close relationship of 99% between this strain of M. palmivorus (MG717877.1) and international strains. On the other hand, the maximum antagonistic effect of M. palmivorus has been found to act against Fusarium solani and F. thapsinum, and to a lesser degree against Penicillium sp., T. harzianum, and P. cyclopium after 6 to 8 days of incubation. Results confirm the precise nomination of this taxon is M. palmivorus, which may act as a bioherbicidal and could be used as bioagent against various phytopathogenic fungi.

Many bioagent fungi have promising potential as eco-friendly alternatives to fungicides, with considerable antagonistic activity against various phytopathogenic fungi. The present study aimed to investigate the antagonistic activity of Trichoderma harzianum and Pleurotus ostreatus isolates against Fusarium spp., the causative agents of wilt disease in cucumber plants, through a dual plate assay of volatile and nonvolatile compounds from these bioagent fungi. The results showed significant (P < 0.05) antagonistic activities of T. harzianum against the growth of F. solani AJA2 (62.3%), followed by F. oxysporum AJA (55.2%), F. incarnatum AJA (53.2%), and F. solani AJA1 (50.8%). The effectiveness of P. ostreatus against the four Fusarium species was notably less than that of T. harzianum. In contrast, in the dual culture assay, the bioagent fungal filtrate exhibited inhibitory effects on the growth of all pathogens at 25% concentration. The highest inhibition rate (85%) was shown by T. harzianum against F. incarnatum. The percent of inhibition caused by P. ostreatus was substantially lower than that caused by T. harzianum, which reached 35% in F. incarnatum followed by other pathogens. The volatile compounds of T. harzianum led to a high percentage of inhibition of all the three Fusarium species, while the highest percentage of inhibition due to the compounds of P. ostreatus was observed only for F. solani AJA1 (41.5%). From these results, we concluded that despite the diverse inhibitory effects of both bioagent fungi against Fusarium species, they exhibited successful antagonistic activity and the ability to compete against these species.