Effects of chitosan oligosaccharide-amended fungicide treatments on the control of fusarium head blight in wheat
Fusarium Head Blight (FHB) is a destructive fungal disease of wheat caused primarily by Fusarium gramineraum, which reduces grain yield and quality through the accumulation of mycotoxins, especially deoxynivalenol (DON). Current management strategies rely heavily on fungicide applications; however, their effectiveness varies among active ingredients, and overuse may lead to fungicide resistance and environmental concerns. Chitosan oligosaccharide (COS) is a product derived from chitin deacetylation that has been studied for its diverse biological properties and applications in various fields, including its ability to inhibit some fungi that cause plant diseases. In this study, greenhouse and field trials were conducted to evaluate the potential of COS, applied isolated and in combination with site- specific fungicides (tebuconazole, metconazole, pydiflumetofen, and thiophanate- methyl), for FHB management and reduction of DON levels in wheat grains. In greenhouse trials, FHB severity was assessed at 8-, 11-, 14-, 17- and 20-days post inoculation. Then, the area under the disease progress curve was determined. The severity at 20 days post-inoculation also was evaluated. In the field, disease incidence and severity, test weight, thousand-kernel weight, and grain yield per plot were evaluated. Additionally, DON concentration and the percentage of Fusarium- damaged kernels were determined for kernels samples harvested in all trials. Overall, COS alone had a limited effect on FHB suppression under both greenhouse and field conditions. However, when combined with pydiflumetofen, the mixture significantly improved disease control, enhanced grain quality and yield, and reduced DON accumulation compared to the fungicide applied alone. The COS–thiophanate-methyl combination also increased fungicide efficacy by reducing disease, Treatments based on tebuconazole and metconazole also showed strong performance, with efficacy rates exceeding 90% in some cases. Although COS demonstrated direct action against F. graminearum, its relatively low standalone efficacy suggests that it should be used as an adjuvant rather than a fungicide replacement for fungicides. These findings support the integration of COS into chemical control programs to improve FHB management. Keywords: Fusarium graminearum; Chemical control; Triticum aestivum;Plant protection; Deoxynivalenol
Trigo - Doenças e pragas - Controle, Fungos fitopatogênicos - Efeito dos fungicidas, Fusarium, Quitosana
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