Molecular confirmation of Stenocarpella maydis causing ear rot of maize in Mexico

Maize is the main staple food in Mexico and one of the most important crops worldwide. Among the multiple diseases affecting maize production throughout its growing cycle, Stenocarpella (Diplodia) diseases of maize cause important ear and stalk rots. During October 2019, ear rot symptoms were observed on maize plants in two commercial fields located in Mixquiahuala, Hidalgo and Huimanguillo, Tabasco, Mexico. The affected ears were normal in size but underweight, with the presence of abundant mycelium between kernels and the subsequent development of pycnidia. From infected ears a single fungus was consistently isolated. Through morphological and phylogenetic studies, the identity of Stenocarpella maydis was confirmed. To test the pathogenicity of the isolates, Koch's postulates were carried out by inoculating healthy ears with two isolates of this fungus. This report confirms the presence of S. maydis causing ear rot on maize in Mexico.