Risk evaluation of deoxynivalenol levels in Bavarian wheat from survey data

Abstract

Fusarium head blight is a world-wide problem in wheat growing areas. The severity of the disease is influenced by weather conditions and agronomic factors. Based on the data of 3119 winter wheat samples from 1993 to 2002, the important risk factors for deoxynivalenol (DON) levels at harvest were evaluated. The overall median DON value ranged from 30 µg kg–1 in 2001 to 281 µg kg–1 in 2002. The risk factors weather conditions at flowering, preceding crop, no or minimal tillage, susceptible cultivar, strobilurin as foliar fungicide (EC 31–EC 59) and late harvest contributed to elevated levels of DON. In every year maize, especially grain maize as preceding crop and minimum tillage had the highest DON values. The number of risk factors affecting the DON level at harvest is not additive, but rather multiplicative. Therefore high DON values in Bavarian wheat are generally caused by more than three risk factors, although conducive weather conditions are indispensable. Therefore an integrated approach to the disease is appropriate to reduce the risk of high DON values in Bavarian wheat. It is shown for the first time that the application of strobilurin as foliar fungicide is a risk factor that contributes to elevated levels of DON.