Distribution of prothioconazole and tebuconazole between wheat ears and flag leaves following fungicide spraying with different nozzle types at flowering

Abstract

Wheat ears are difficult targets from the aspect of fungicide spraying. Sideward-spraying nozzle types may enhance the ear coverage, which may possibly lead to higher effectiveness in the management of Fusarium head blight (FHB). On average, sideward-spraying Turbo TeeJet Duo nozzles resulted in 1.30 and 1.43 times higher prothioconazole-desthio and tebuconazole contents and Turbo FloodJet nozzles in 1.08 and 1.34 times higher prothioconazole-desthio and tebuconazole contents in wheat ears by comparison with those achieved with vertically-spraying XR TeeJet nozzles. In contrast, the vertically-spraying XR TeeJet nozzles resulted in 1.57 and 1.31 times higher prothioconazole-desthio and tebuconazole contents in the flag leaf blade. The degradation of the active ingredient (AI) depended on the year, the cultivar and the plant organ, but not on the spraying method. There was no clear relationship between the efficacy of a given nozzle type and the outcome of the FHB epidemic. The ear coverage and therefore the AI content have been improved with the two sideward-spraying nozzle types. There was no effective translocation of the AI content between the ears and flag leaf blades. Prothioconazole and tebuconazole proved to be highly effective in the management of FHB, but the FHB resistance of the cultivar was also decisive.