Evaluation location: Iowa, United States
350 maize accessions from the NCRPIS collection were evaluated in 2000 for resistance to northern leaf blight (NLB), caused by Exserohilum turcicum race O and eyespot, caused by Kabatiella zeae. Plots were planted on 9-May-2000 at the Hinds Research farm, Ames, IA. The trial included two replicates of single rows with approximately 20-25 plants per row. Rows were spaced 0.76 m apart. Plants were inoculated on 27-JUN and 03-JUL. The first half of each row was inoculated with eyespot and the second half with northern leaf blight. Initial eyespot ratings were made on 25-JUL with a second rating made between 21-AUG and 24-AUG. During the initial eyespot rating, an average lesion diameter (in mm) was measured. The score for the latter rating date was used to determine the final accession rating except for early maturing accessions where the first score was used. Each plot was given an overall score based on the average disease development on all plants in the plot. Scores for the two replications were averaged to obtain an overall rating for each accession. First Eyespot Rating (0-5 scale):0 = no disease;1 = few lesions per leaf;2 = areas of 20 or more lesions on leaf;3 = over 50 lesions per leaf;4 = 200 or more lesions per leaf;5 = some areas of leaf dead due to eyespot. Second Eyespot Rating (0-9 scale); expansion of 0-5 scale:General categories:1-3 = low disease;4-6 = moderate disease;7-9 = severe disease. Specific categories:0 = no disease;1 = few lesions per leaf;2 = moderate number of lesions per leaf below ear;3 = numerous lesions on leaves below the ear, but no evidence of lesion coalescence;4 = numerous lesions with some patches of leaf tissue killed below the ear;5 = whole leaves killed up to the ear and some disease evident above the ear;6 = heavy disease over whole plant, some leaves above the ear severely infected;7 = heavy disease over whole plant and some leaves above the ear killed;8 = all leaf tissue above ear nearly completely diseased;9 = plants dead.