The role of organic vs. conventional farming practice, soil management and preceding crop on the incidence of stem-base pathogens on wheat

A stem-base disease complex of winter wheat includes several causal agents, such as eyespot ( Oculimacula yallundae and O. acuformis ), sharp eyespot ( Rhizoctonia cerealis ) and brown foot rots ( Fusarium graminearum , F. culmorum , F. avenaceum , F. po ae , Microdochium nivale vars. nivale and majus ). Farming practices (organic and conventional), soil management (ploughing compared to min- and no-tillage) and the preceding crop (cereal, maize and oilseed rape) were studied as factors affecting the incidence of stem-base pathogens. The stem-base diseases were assessed visually and by molecular methods (PCR) on four winter wheat cultivars at four growth stages. The comparison of organic and conventional farming practices did not result in large differences in the relative incidence of stem-base pest species over the period of this study; nevertheless, a higher frequency of positive detection was recorded for three organisms ( O. acuformis , O. yallundae and M. nivale var. nivale ) under conventional farming. Other factors had none or only partial effects. Soil management didn’t affect the stem-base pathogens incidence significantly. The preceding crop maize reduced the incidence of M. nivale var. majus .