Yield loss and identification of variety resistance to black bundle of maize

The resistant and susceptible varieties of maize to Acrimonium strictum had different yield. Infected plants could not form female ears or decreases of grain number per ear and 1 000grainweight. The average yield loss was up to 66.0%. The yield loss for disease tolerant variety was mainly caused by the decrease of grain number per ear, and the average yield loss was 14.7%. Soil inoculation test was applied to 1 382 maize accessions in 2005 and 2006. It was showed that 1 097 accessions or 79.3% were not infected, 5 were highly resistant and another 5 were resistant accessions, each accounting for 0.36%; 15 accessions were disease tolerant and accounting for 1.08%; 27 (2.0%) were sensitive accessions; 233 accessions or 16.9% were highly sensitive. Meanwhile, preliminary study was conducted on the relationships between the content of stem reductive sugar, total phosphorus, total nitrogen, coarse protein and disease resistance of varieties.