Influence of maize-wheat rotation systems on Fusarium head blight infection and deoxynivalenol content in wheat under low versus high disease pressure

Fusarium head blight (FHB) is one of the most destructive fungal diseases of small grain cereals resulting in a reduced grain yield and quality. FHB is the result of a complex interaction between weather conditions and agricultural practices including crop rotation, tillage, fungicide application and host resistance. This study deals with the results of field experiments conducted during the growing seasons 2009-2010 until 2011-2012 at Bottelare (Belgium). The experiments were set up to evaluate the influence of maize-wheat rotation on the visual symptoms of FHB and deoxynivalenol (DON) content in winter wheat. Using a randomised complete block design with four replications, we studied the impact of (a) maize variety as previous crop, (b) maize harvest method (grain or silage maize), (c) tillage method and (d) the influence of the wheat variety resistance on the FHB incidence and DON content. The experimental results showed that the susceptibility of the maize varieties for Fusarium and maize harvest method had only a minor effect on the FHB incidence and DON content of the wheat crop during the subsequent growing season. The tillage method and wheat variety resistance were more important; both factors had a significant influence on the FHB incidence and DON content. Furthermore, the quantitative effect of these factors depended on the disease pressure. The DON content reduction obtained by ploughing and by sowing moderately resistant wheat varieties was higher in case the weather conditions favoured FHB development. Furthermore, it was shown that repeated maize-wheat rotation in combination with favourable weather conditions for FHB could result in an accumulation of inoculum, which, for instance, led to DON contents up to 9.90 mg/kg in August 2012.