Effect of prothioconazole-based fungicides against Fusarium Head Blight and deoxynivalenol accumulation in wheat under field conditions

Fusarium head blight (FHB) of wheat is a disease caused mainly from fungi of the genus Fusarium and Microdochium nivale that, under favourable environmental conditions, can colonize plants during the production cycle and cause serious damages in terms of yields and quality of harvested grains. Deoxynivalenol (DON), a trichothecene mycotoxin produced by Fusarium culmorum and F. graminearum that can contaminate wheat causing haematic and anorexic syndromes and neurotoxic and immunotoxic effects in mammals, is often associated with FHB disesase. Strategies for FHB control include the use of good agronomic practices (GAP), resistant varieties and effective fungicides. Prothioconazole is a triazolinthione fungicide with ideal systemic properties providing protective, curative and long lasting activity. In order to evaluate the effectiveness of prothioconazole-based treatments against FHB disease severity, grain yields and the consequent accumulation of DON in wheat kernels, several field experiments have been performed during four consecutive growing seasons (from 2004 to 2008) in the North of Italy. Fungicide treatments were carried out on different cultivars of soft wheat (Blasco and Serio) and durum wheat (Saragolla and San Carlo) after artificial inoculation with a mixture of toxigenic F. graminearum and F. culmorum strains. The application of fungicides containing prothioconazole at the beginning of anthesis (BBCH 61) resulted in a consistent reduction of FHB disease severity (by between 50 and 70%), a strong reduction of DON levels in wheat kernels (by between 40 and 90%), and an increasing of wheat yields ranging from 0.5 to 6.0 t ha-1 (average value 2.0 t ha-1), as compared to the untreated/inoculated control and to treatments with fungicides containing tebuconazole and cyproconazole plus prochloraz. These results show that the application of fungicides containing prothioconazole provide a strong reduction of the FHB disease, allowing both an increase in grain yields and a considerable reduction of DON content in the wheat kernels.