Evaluation of Maize Hybrids for Identifying Resistance to Northern Corn Leaf Blight in Northeast China

Northern corn leaf blight (NCLB) caused by Setosphaeria turcica is one of the most devastating foliar diseases in maize (Zea mays L.), resulting in great economic losses worldwide. The mutation of the pathogen exacerbates the occurrence and harmfulness of NCLB in China. Therefore, there is an urgent need for evaluating and cultivating resistant hybrids. Here, the response of 239 maize hybrids approved in Northeast China to NCLB was evaluated during 2019 and 2020. The results showed that 92 (38.49%) and 75 (31.38%) hybrids were rated as moderately resistant and resistant, respectively, which together constituted the predominant resistant categories. We observed that maize hybrids from different certified sources had different levels of resistance to NCLB, whose disease parameter values varied significantly (P < 0.05) among 52 main cultivated hybrids. In 2019 and 2020, the average size of the lesions increased from 21.02 to 21.06 cm², the average lesion density decreased from 1.36 to 1.33 lesions/100 cm², and more than 30% of the hybrids registered final disease severity scores between 10 and 30%. The area under the disease progress curve of the main cultivated hybrids ranged from 57.96 to 986.86 cm² in 2019 and from 50.75 to 1,028.65 cm² in 2020. Correlation analysis revealed a significant relationship (P < 0.0001) among four disease parameters. Current research has shown that many maize hybrids in Northeast China are resistant to NCLB, suggesting that the large-scale cultivation of susceptible hybrids has led to the occurrence and prevalence of the disease. This study should assist growers in purposefully selecting resistant commercial hybrids to contribute to the management of NCLB.