Biocontrol Potential of Trichoderma asperellum Strain 576 against Exserohilum turcicum in Zea mays

Maize is a crucial cereal crop in China, serving both as a staple food and an essential industrial resource. Northern corn leaf blight (NCLB) is a disease of corn caused by a fungus, Exserohilum turcicum (sexual stage Setosphaeria turcica). This study aimed to assess the biocontrol potential of various Trichoderma strains against Exserohilum turcicum 101 in Jilin, China. Through dual culture tests, the Trichoderma strains were categorized into four groups based on their antagonistic abilities. Eleven Trichoderma strains exhibited strong antagonistic behavior, with comparable or faster growth rates than E. turcicum 101. Microscopic observations confirmed that T. asperellum 576 hyphae effectively encircled E. turcicum 101 hyphae, reinforcing their antagonistic behavior. The production of non-volatile and volatile substances by the Trichoderma strains was evaluated, with T. asperellum 576 showing the highest potency in producing non-volatile and volatile substances, leading to an impressive 80.81% and 65.86% inhibition of E. turcicum 101 growth. Remarkably, co-culture suspensions of T. asperellum 576 + E. turcicum 101 and T. atroviride 393 + E. turcicum 101 exhibited strong antifungal activity. Furthermore, the activities of chitinase, β-1.3-glucanase, and cellulase were evaluated using the 3, 5-dinitrosalicylic acid (DNS) method. T. asperellum 576 + E. turcicum 101 displayed stronger cell wall degradation enzyme activity compared to T. atroviride 393 + E. turcicum 101, with values of 8.34 U/mL, 3.42 U/mL, and 7.75 U/mL, respectively. In greenhouse conditions, the application of a 10(7) spores/mL conidia suspension of T. asperellum 576 significantly enhanced maize seed germination and plant growth while effectively suppressing E. turcicum 101 infection. Maize seedlings inoculated/treated with both E. turcicum 101 and T. asperellum 576 demonstrated substantial improvements compared to those inoculated solely with E. turcicum 101. The T. asperellum 576 treatment involved a 10(7) spores/mL conidia suspension applied through a combination of foliar spray and soil drench. These findings highlight T. asperellum 576 as a promising biocontrol candidate against northern leaf blight in maize. Its antagonistic behavior, production of inhibitory compounds, and promotion of plant growth all contribute to its potential as an effective biocontrol agent for disease management.