Incidencia de Ustilago maydis (D.C) Corda en cultivares comerciales de maíz en el valle de Toluca, estado de México

Abstract

The “huitlacoche” fungus is caused by the phytopathogen Ustilago maydis, which is considered by many to be an undesirable disease that severely attacks maize crops and leads to large economic losses for the farmer. In Mexico, though, huitlacoche is highly valued in Mexican cuisine and is used to prepare a wide variety of dishes. However, huitlacoche production is very limited and it is only available on the market during August and September, despite year-round demand. The objective of this study was to identify different maize genotypes that could be used to produce huitlacoche in the Toluca Valley during two consecutive years (2019-2020). To do this, we evaluated the incidence and severity of infection induced in different maize genotypes, in addition to classifying the degree of resistance and susceptibility that each variety presented to the U. maydis pathogen. The results showed that nearly all of the varieties were susceptible to the fungus to some degree. During the first year of the study, the H-40 variety showed the highest percent incidence and was classified as very susceptible (VS). The Albatros variety presented a high index of severity, while the A-7573 variety and the Stratus hybrid did not present any signs of infection. During the second year, the hybrids Z-60 and H-66 had the highest incidence and average severity indices recorded during either year of the study, and like the H-40 variety, were classified as VS. Meanwhile, the Z-476-19 and Carioca varieties had the lowest percent incidence recorded that year and were classified as moderately resistance (MR). That same year, the hybrids H-50 and LR1 presented the lowest severity index values, 6.17 and 5.38 respectively. These results indicate that infection with the U. maydis pathogen varies depending on the maize genotype, making it advisable that the varieties classified as VS be used for mass production of huitlacoche.