Translocation and degradation of tebuconazole and prothioconazole in wheat following fungicide treatment at flowering

Abstract

BACKGROUND: Prothioconazole and tebuconazole are among the most effective fungicides against Fusarium head blight (FHB) of wheat (Triticum aestivum L.). The translocation between the ears and the flag leaves and the kinetics of degradation may influence field efficacy of these active ingredients (AIs). RESULTS: In greenhouse experiments, only traces (<1%) of the total AI content translocated from the flag leaves to the ears, and a maximum of 3.55% from the ears to the flag leaves. From the treated to the non-treated side of the ears, 3.2-15.9% of the AI translocated, depending on cultivar, AI and time. In field experiments, the degradation kinetics in the first 8days after treatment revealed a higher velocity in the flag leaf blades than in the ears, although both were dependent on the type of cultivar. The fungicide treatment resulted in 42.6-100% decreases in FHB traits. CONCLUSIONS: There is no effective translocation of these AIs, only moderate redistribution in the ears, which can be decisive from the aspect of FHB management. The degradation of prothioconazole was faster than that of tebuconazole. Cultivar and environmental effects influenced the degradation kinetics of these AIs, but a high level of protection against FHB was maintained. © 2013 Society of Chemical Industry.