<p>Northern corn leaf blight (NCLB) is a major disease affecting maize worldwide. Understanding resistance and tolerance mechanisms is crucial for developing effective control strategies. This study evaluated genetic variability in landraces, the seed from the Far West of Santa Catarina (FWSC), known for their diverse traits, to assess their potential for resistance and tolerance to NCLB. Two experiments were conducted during the 2019/2020 season using a randomized block design with four replications. One experiment included inoculation with <i>Exserohilum turcicum</i> (2 × 10³ spores mL⁻¹) without chemical control, while the other utilized fungicide (difenoconazole) to suppress the disease. Key traits assessed were incubation period (IP), latency period (LP), lesion type (LT), severity measured by the area under the disease progress curve (AUDPC), and corn ear productivity (Yield). Significant differences (p ≤ 0.001) were observed among genotypes for LP and Yield in the absence of chemical control, highlighting the performance of landrace 2029A and the commercial variety BR401. Joint analyses for variables common to both experiments Yield and AUDPC revealed significant differences (p ≤ 0.005) between treatments, allowing tolerance evaluation based on yield losses and disease severity increments. This is the first report of qualitative resistance genes in landraces in southern Brazil. These findings underscore the potential of landraces for germplasm conservation and breeding programs aimed at enhancing NCLB resistance and tolerance. The use of fungicide provided a baseline for comparing tolerance, demonstrating its relevance for assessing productivity under pathogen pressure.</p>