Effect of temperature on head blight of wheat caused by Fusarium culmorum and F. graminearum

Abstract

The effect of small temperature differentials (16 vs. 20°C) on the pathogenicity of deoxynivalenol producing single isolates of Fusarium culmorum and R graminearum and on the fusarium head blight (FHB) response of eight wheat cultivars was examined. Fusarium culmorum inoculation caused greater visual disease symptoms at 20°C than at 16°C, both overall and on an individual cultivar basis (overall AUDPC = 13.5 and 9.6, respectively) (P < 0.05). In contrast, F. graminearum inoculation caused greater overall visual disease symptoms at 16°C than at 20°C, both overall and at the individual cultivar level (overall AUDPC = 12.8 and 10.9, respectively) (P < 0.05). Results showed both F. culmorum and F. graminearum inoculations caused a greater loss in yield at 20°C (54.3 and 46.9% relative 1000-grain weight, respectively) compared with 16°C (73.3 and 66.9% relative 1000-grain weight, respectively) (P < 0.05). Fusarium culmomm-inoculated heads contained similar amounts of fungal DNA at both 16 and 20°C (1.9 and 1.7 ng mg -1 of plant material, respectively) (not significant), while for F. graminearum inoculation, plants contained higher amounts of fungal DNA at 20°C (2.0 and 1.0 ng mg-1 of plant material, respectively) (P < 0.05). Overall, there was a significant negative correlation between AUDPC and percentage relative 1000-grain weight at both 16 and 20°C (r =-0.693 and -0.794, respectively, P < 0.01). © 2005 BSPP.