Abstract :
Although it is generally agreed that most Fusarium head blight infection takes place during the wheat
flowering 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 of
toxins. Such infections are not taken into account by predictive models. To explore the effect of infection time
on disease severity, Fusarium-damaged kernels (FDK), desoxynivalenol (DON) and zearalenone (ZON), an
experiment was set up in 2009 on two varieties. The experiment had a split-plot design. Plots were inoculated
by spraying Fusarium graminearum conidia at different stage, from heading to ripening. Inoculation time had
a significant effect on disease severity, FDK, DON and ZON levels (P < 0.0001), as well as interaction between
variety and inoculation time. The results of this trial have shown no significant difference between infection at
heading, 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 and
toxin 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.
