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 northern leaf blight ratings were made on 27-JUL with a second rating made between 24-AUG and 25-AUG. An average lesion length (in inches) of individual lesions was also made during the first rating date. Notes were made of any accessions with plants that expressed a chlorotic lesion response like Ht1. 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.Reps were averaged. 1st northern leaf blight, 0-5 rating scale:0 = no disease;1 = lesions not present on every plant, usually five or fewer lesions per row;2 = one or two lesions per plant;3 = several lesions per plant;4 = heavy lesions, may be killing leaves;5 = several dead leaves. Second northern leaf blight, 0-9 rating scale; expansion of 0-5 scale:0 = no disease;1 = lesions not present on every plant;2 = a few lesions per plant;3 = numerous lesions per plant, but no evidence of lesion coalescence;4 = numerous lesions per leaf with some patches of leaf tissue killed below the ear;5 = whole leaves killed below 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.