Effect of the previous crop on Fusarium spectrum and mycotoxin contamination in grains of winter wheat

Abstract

The effect of maize, sugarbeet and wheat on the incidence, mycotoxin load and composition of the Fusarium population in ears of a following crop of winter wheat was studied in three-year rotation trials at two locations north of Gottingen. The weather conditions for Fusarium infection of wheat ears varied in the trial years 2007, 2008 and 2009. Comparison of the weighted factor effects showed the dominating importance of the weather for the mycotoxin content of the grains. The deoxynivalenol contents at the two locations differed significantly; the relative location effects were independent of the trial years. In contrast, the factor effects of the three previous crop variants maize, winter wheat and sugarbeet varied between years. In 2009, a year of average incidence, it was possible to differentiate between all three previous crop variants. However in 2007, a year of heavy incidence, there was no significant difference in mycotoxin content of the grain samples between the previous crop variants sugarbeet and winter wheat; only the samples of the previous crop variant maize could be distinguished. The composition of the fungus population on the ears showed that Fusarium graminearum occurred as the leading pathogen independently of the previous crop and the year effect. It can be concluded from these studies that the relative previous crop effect of sugarbeet and wheat on the mycotoxin content of a following winter wheat crop depends on the seasonal yearly weather and the resultant incidence pressure of ear Fusarium. The causes that can lead to unexpectedly increased mycotoxin levels in higher risk years also in sugarbeet are yet to be fully elucidated.