Characterization, Biocontrol, and Fungicide Sensitivity of Macrophomina phaseolina Isolates Associated with Charcoal Rot of Sesame in Northern Sinaloa, Mexico

Macrophomina phaseolina is a plant-pathogenic fungus that causes charcoal rot in sesame crops, which is the most significant disease affecting this crop worldwide. In Mexico, the interaction between M. phaseolina and sesame has been poorly studied. Therefore, this research aimed to characterize Macrophomina spp. isolates from diseased sesame roots in northern Sinaloa, Mexico, using morphological, molecular, and pathogenic methods. It also assessed the in vitro effectiveness of biocontrol agents and chemical fungicides. Six isolates of Macrophomina were identified through morphology, species-specific tef1-α primers, and phylogenetic analysis of DNA sequences (ITS + tef1-α), confirming their identity as M. phaseolina; all isolates proved to be pathogenic. Antagonism assays with Trichoderma spp. showed statistically significant differences. Trichoderma isolates inhibited mycelial growth by up to 63% against M. phaseolina. In fungicide sensitivity tests, M. phaseolina isolates showed EC50 values ranging from 0.002–0.123, 0.049 to 1.397 and 0.029 to 0.539 mg L−1 for thiophanate-methyl, tebuconazole, and pyraclostrobin, respectively. In summary, Trichoderma spp. isolates and the tested fungicides warrant further research as potential strategies to manage M. phaseolina in sesame fields.