Effects of soil tillage and crop rotation on the development of wheat stem base diseases

Wheat stem base disease (WSD) is an important disease complex which can be caused by various pathogens with variable life cycles, ecological requirements and sensitivities to fungicides. Agronomic practices are considered important tools to control this disease complex and influence the spectrum of fungal communities in infected wheat stems. The aim of the present study was to determine the impact of crop rotation schemes and soil tillage methods on the development of WSD and to elucidate the spectrum of causal agents of this disease. The development of WSD was assessed in a two-factorial (soil tillage practice and crop rotation) experiment. The incidence of WSD was evaluated at the BBCH growth stages 83-85. Causal agents of WSD and other fungi were identified using molecular methods. The soil tillage method did not influence the development of WSD, but the impact of crop rotation was significant, and the cropping system where oilseed rape, barley and faba beans were included decreased disease levels. Members of the genera Oculimacula and Fusarium were the most prevalent fungi associated with WSD. Moreover, fungi from other taxonomic groups were detected, with Phaeosphaeria spp. being prevalent. An increasing occurrence of Microdochium spp. was also observed. In conclusion, agronomic practices influenced the level of WSD, but no distinct impact on the fungal spectrum was identified. Further investigation is required to clarify the roles that pathogens and fungi from other taxonomic groups play in the fungal-wheat relationship.