Evaluation of Sweet Corn Lines for Resistance to Northern Corn Leaf Blight Disease Caused by Exserohilum turcicum

Abstract

The reaction of 36 sweet corn varieties/ lines to northern corn leaf blight disease ( NCLB) were examined at Chiang Mai Field Crops Research Center in dry season, 2023. A randomized complete block design with two replicates was deployed. Fungi were cultured by dropping over the outside row and then left the disease to spread naturally. At 28 days after plantation, it was found that all sweet corn lines were moderately resistant to disease and showed a disease rate between 11.2 – 17.0 percent of leaf area infected, compared to 10 commercial sweet corn varieties including Hibrix-3, Hibrix-59, Hibrix-72, Dr.Pex Wan 56, Dr.Pex Wan 1351, Dr. Pex Wan 1796, Sugar 75, Insee 2, Songkhla 84- 1 and Chai Nat 2 which were moderately resistant to disease and showed a disease rate between 14.6 – 21.2 percent of leaf area infected. In addition, at 55 days after plantation, all sweet corn lines, were moderately susceptible to disease and showed a disease rate between 40. 9 – 61. 1 percent of leaf area infected, compared to 10 commercial sweet corn varieties which were moderately susceptible to disease with a disease rate between 44.9 – 67.8 percent of leaf area infected. However, the experimental results can select two sweet corn lines that have NCLB disease resistance levels higher than commercial varieties, which are CH66C1)-9-311211/HX75C1)-17-221111 and CH66C1) - 9- 311211/ HX75C1) - 8- 122111, with disease rates of 40. 9 and 44. 4 percent of leaf area, respectively. These can be used in breeding programs for disease resistance.