Effects of Infection Time by Fusarium Graminearum on Ear Blight, Deoxynivalenol and Zearalenone Production in Wheat

Although it is generally agreed that most Fusarium head blight infection takes place during the wheatflowering period, very rainy conditions at the end of the plant growth, such as occurred in France in 2007,raise the question of the possibility of late infections on the development of the disease and the production oftoxins. Such infections are not taken into account by predictive models. To explore the effect of infection timeon disease severity, Fusarium-damaged kernels (FDK), desoxynivalenol (DON) and zearalenone (ZON), anexperiment was set up in 2009 on two varieties. The experiment had a split-plot design. Plots were inoculatedby spraying Fusarium graminearum conidia at different stage, from heading to ripening. Inoculation time hada significant effect on disease severity, FDK, DON and ZON levels (P<0.0001), as well as interaction betweenvariety and inoculation time. The results of this trial have shown no significant difference between infection atheading, anthesis and post-anthesis until 15 days for disease severity, FDK and mycotoxins levels. Nevertheless, this trial has suggested different behaviour between the two varieties according to infection time andtoxin accumulation. The period of high susceptibility to Fusarium graminearum has appeared unstable between varieties, ranging from closed to flowering to a large period from heading to several days after flowering.