Leaf Spot Disease Caused by Several Pathogenic Species of the Pleosporaceae Family on Agave salmiana and Agave lechuguilla Plants in Mexico, and Their Biocontrol Using the Indigenous Trichoderma asperellum Strain JEAB02

The genus Agave (family Asparagaceae) represents the second-most important group of plants in Mexico. Several fungal species have been identified as causal agents of leaf spot disease affecting Agave salmiana and A. lechuguilla, producing necrotic lesions that compromise plant health and productivity. Pathogenicity experiments were conducted under greenhouse conditions, field tests were performed, and in vitro antagonism using Trichoderma asperellum strain JEAB02 against selected pathogenic isolates was evaluated. Phylogenetic analysis of genomic DNA fragments allowed the identification of 26 fungal isolates belonging to Curvularia lunata, C. verruculosa, Bipolaris zeae, Alternaria alternata, Fusarium lactis, Epicoccum sorghinum, Myrmaecium rubricosum, Penicillium diversum, and Aspergillus oryzae. In pathogenicity assays under greenhouse conditions on A. salmiana and A. lechuguilla, treatments T5–T12 exhibited statistically similar levels of disease severity (33.10–37.29%), caused mainly by C. verruculosa, A. alternata, B. zeae, and F. lactis. In field tests, Agave plants inoculated with the selected pathogenic fungi (T4, T5, T7, T8, T10, and T11) showed 21.07–36.73% leaf damage after 75 days. The antagonistic effect of T. asperellum JEAB02 caused complete (100%) growth inhibition of the pathogenic isolate JCPN27 and inhibition levels from 99.81 to 99.98% for isolates JCPN18, JCPN24, JCPN28, JCPN29, JCPN31, and JCPN33, demonstrating its high potential as a biological control agent.