Comparison of visual head blight ratings, seed infection levels, and deoxynivalenol production for assessment of resistance in cereals inoculated with Fusarium culmorum

Seven spring wheat, 13 barley, 14 oats and 20 winter wheat genotypes were inoculated at flowering in 1993 and 1994 with mixed conidial suspensions of 8 isolates of Fusarium culmorum. Four weeks after inoculation, head blight was recorded in the field. After harvest, seed infection was assessed by a Freezing Blotter Test in the laboratory. Seed samples were also analyzed for deoxynivalenol (DON) content. Differences were found in head blight rating, the levels of infected seeds and the DON content between wheat, barley, and oats and between cultivars. Highly significant correlations were found between the percentage of heavily infected seed and the DON content. The weighted mean value of infected seeds and DON content were also significantly correlated. No significant correlation was found between head blight rating in the field and DON content. The level of infected seeds, as determined by the Freezing Blotter Test, was a better indication of the DON content in the seeds than the head blight rating. This visual assessment of levels of infected seeds gives a reliable estimate of resistance to Fusarium.