Chang, K. F., Hwang, S. F., Ahmed, H. U., Strelkov, S. E., Gossen, B. D., Turnbull, G. D. and Blade, S. F. 2014. Disease reaction to Fusarium avenaceum and yield losses in narrow-leafed lupin lines. Can. J. Plant Sci. 94: 1211-1218. Seedling blight and root rot caused by Fusarium avenaceum are important constraints to the expansion of lupin (Lupinus angustifolius) production in Alberta, Canada. The reaction of 19 narrow-leafed lupin lines to F. avenaceum was assessed in inoculated field trials in Alberta from 2006 to 2008. Although none of the lines were highly resistant to F. avenaceum, the lines F6RF, MLU-122 and MLU-318-1 had the smallest reduction in emergence and MLU-320 and MLU-324 had the smallest reduction in seed yield as a result of inoculation under field conditions. The stability analysis of yield revealed that lupin lines MLU-324, W12-W5, MLU-320 and MLU-318-1 were more stable in comparison to other lupin lines included in the study. Yield loss was not consistently associated with seedling emergence, likely because the seeding rate may have been higher than required to achieve the yield potential of these lines in Alberta. A companion field study was conducted at Lacombe, Alberta, in 2006 and Edmonton, Alberta, in 2007; seedling emergence and seed yield of the susceptible lupin cv. Arabella declined linearly with increasing levels of seed infestation, and the relationships were summarized using regression analysis. Seedling emergence and yield were strongly correlated.