Abstract
ABSTRACT Fusarium head blight (FHB) is considered a disease of difficult control in a scenery of obstacles for its chemical control and due to the aggressiveness of its pathogen in producing toxins. Thus, the objective of this study was to verify if fungicides of different chemical groups, alone or in combination, are effective in controlling fusarium head blight and reducing deoxynivalenol (DON) contamination in wheat grains. In addition, pyraclostrobin alone was evaluated for possible changes on fusarium head blight intensity and DON accumulation reflecting on the yield. The experiments were conducted in the field, in a randomized block design, containing 11 treatments and four replicates, using the cultivar TBIO Toruk. The treatments were composed of the fungicides triazole, strobilurin and benzimidazole alone, besides the commercial mixture of triazole + strobilurin. Two fungicide applications were performed during the crop flowering. Fusarium head blight intensity, control efficacy, DON contamination and grain yield were evaluated. Data were subjected to analysis of variance (F-Test at 5%) and means were compared according to Scott-Knott test, at 5%. Carbendazim alone presented greater control efficacy in the two studied years (67% and 75%, respectively), differing from metconazole and pyraclostrobin. Pyraclostrobin at different doses and application stages changed fusarium head blight intensity, DON contamination and wheat grain yield.
Highlights
A giberela é considerada uma doença de difícil controle, num cenário de dificuldades no seu controle químico e pela agressividade do patógeno em produzir toxinas
Some fungicides may not be effective in controlling fusarium head blight in severe epidemics; in years of weak epidemics, the use of fungicide may be sufficient to reduce DON contamination [20]
Fungicide application in the vegetative stage of wheat resulted in 20.5% fusarium head blight control; maintenance of healthy plants by controlling foliar diseases in pre-earing has an effect on the intensity of fusarium head blight in spikes
Summary
A giberela é considerada uma doença de difícil controle, num cenário de dificuldades no seu controle químico e pela agressividade do patógeno em produzir toxinas. Among control strategies for fusarium head blight, the use of fungicides has been recommended worldwide, while cultivars showing high genetic resistance degrees are not available to wheat. Some fungicides may not be effective in controlling fusarium head blight in severe epidemics; in years of weak epidemics, the use of fungicide may be sufficient to reduce DON contamination [20]. Benzimidazolic fungicides, especially carbendazim, have been used to control fusarium head blight for several years, especially in China, where resistance to this chemical group has already been reported. Resistance can lead to increased efficiency of the fungus in producing mycotoxins, showing consistency for this fungicide in relation to the disease incidence in spikelets and production of mycotoxins [29]
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