Severidade de Giberela e presença de micotoxinas em cevada mediante diferentes sequências de aplicação de fungicidas

Abstract

Fusarium head blight (FHB), whose asexual form corresponds to Fusarium graminearum, is one of the main diseases causing yield and quality losses of barley grains (Hordeum vulgare L.). The objective of this study was to evaluate the incidence and severity of FHB, mycotoxin production of Deoxynivalenol (DON), F. graminearum recovery from asymptomatic grains and crop yield. The treatments applied at stages of tillering, elongation, booting and flowering of the cultivar BRS ‘Korbel’ were: T1) trifloxystrobin + cyproconazole, trifloxystrobin + tebuconazole, azoxystrobin + tebuconazole, trifloxystrobin + tebuconazole; T2) trifloxystrobin + tebuconazole, azoxystrobin + tebuconazole, trifloxystrobin + prothioconazole, carbendazin; T3) trifloxystrobin + ciproconazole + mancozeb, trifloxystrobin + tebuconazole + mancozeb, azoxystrobin + tebuconazole + mancozeb, trifloxystrobin + tebuconazole + mancozeb; T4) trifloxystrobin + tebuconazole + mancozeb, azoxystrobin + tebuconazole + mancozeb, trifloxystrobin + prothioconazole + mancozeb, carbendazim + mancozeb; T5) control, without fungicide application. The T5 treatment differed statistically from the others presenting greater severity of the fungus. The DON quantification was higher in T2 (721,75 µg/kg), and in T5 there was the lowest contamination (514,05 µg/kg) differentiating from the other treatments. Regarding the incidence of F. graminearum, T3 (55,00%), and T4 (47,50%) showed the lowest incidences of the pathogen differing statistically from the others. Barley yield was higher in T1 (4295,1 kg.ha1) and T5 (3691,4 kg.ha1), treatments, which presented statistical difference over the others, and T4 6 presented the lowest yield (1974,1 kg.ha1). For the variables hectoliter weight and weight of a thousand grains, it was verified that there was no statistical difference.