Minimizing yield losses and sanitary risks through an appropriate combination of fungicide seed and foliar treatments on wheat in different production situations

Among the fungal diseases that affect wheat in temperate growing areas, Septoria Leaf Blotch (SLB) and Fusarium head blight (FHB) result in yield and sanitary risk losses that could be minimized through appropriate fungicide applications. Furthermore, the request from policy makers and the food market to reduce the use of chemical pesticides in agriculture has driven research in the direction of performant defense strategies with a reduced spraying of pesticides. The aim of this study was to evaluate the effects of different fungicide programs on the control of SLB and FHB, as well as on the grain yield and deoxynivalenol (DON) contamination of common wheat. Field experiments were carried out in 2016 and 2017 in North Italy. Two seed treatments (conventional vs. systemic) and four combinations of foliar fungicide applications (untreated control, application at the end of stem elongation, at flowering, and a double treatment at stem elongation and flowering) have been compared, according to a full factorial design, under two agronomic conditions: plowing vs. minimum tillage. Foliar sprayings at the end of stem elongation were found to be more effective in controlling SLB, while a triazole application at flowering was found to be an essential practice to reduce the FHB and DON contents. The double foliar treatment led to significant benefits, albeit only in the production situations with the highest SLB severity (e.g., in the 2017 experiment, after ploughing and the use of a conventional seed treatment). The systemic seed dressing led to a higher and prolonged STB protection, with significant canopy greenness during ripening in all the production situations. In 2017, which suffered from high disease pressure, the seed treatment with systemic fungicide led to a significant increase in grain yield (+5%), compared to the conventional one. The combination of the systemic seed treatment and the triazole application at flowering guaranteed the highest control of both SLB and FHB, maximized grain yield, and minimized DON contamination. This study provides useful information that could be used to evaluate appropriate fungicide programs, based on a combination of seed and foliar treatments, for wheat yield and sanity in distinct SLB and FHB diseases pressure scenarios.