Effects of field-applied fungicides, grain moisture, and time on deoxynivalenol during postharvest storage of winter wheat grain

Authors: BOLANOS-CARRIEL, CARLOS - University Of Nebraska; WEGULO, STEPHEN - University Of Nebraska; HALLEN-ADAMS, HEATHER - University Of Nebraska; BAENZIGER, PETER - University Of Nebraska; ESKRIDGE, KENT - University Of Nebraska; Funnell-Harris, Deanna

Submitted to: Canadian Journal of Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/16/2019
Publication Date: 6/1/2020
Citation: Bolanos-Carriel, C., Wegulo, S.N., Hallen-Adams, H., Baenziger, P.S., Eskridge, K.M., Funnell-Harris, D.L. 2020. Effects of field-applied fungicides, grain moisture, and time on deoxynivalenol during postharvest storage of winter wheat grain. Canadian Journal of Plant Science. 100(3):304-313. https://doi.org/10.1139/cjps-2019-0075.
DOI: https://doi.org/10.1139/cjps-2019-0075

Interpretive Summary: Fusarium head blight (FHB) disease can cause major losses in wheat due to reduced yield and accumulation of a toxin (DON) that can affect human and animal health. The fungus that causes FHB infects at flowering and produces DON in the grain when climatic conditions are right for growth of the fungus. Triazole fungicides are more effective than strobilurins in controlling FHB and accumulation of DON when applied at flowering. This study reports the effects of field-applied fungicides on DON levels in grain during storage. DON levels were monitored during 120 days of grain storage in darkness at different grain moistures following harvest of winter wheat cultivars Overland and Overley; Overland is more resistant to FHB than Overley. While in the field, the wheat had been treated either with a triazole fungicide, a strobilurin fungicide, or was left untreated. For cultivar Overland, DON decreased more in untreated and triazole-treated grain, than in strobilurin-treated grain. For cultivar Overley, DON actually increased in the untreated- and strobilurin-treated grain but did not change in the triazole-treated grain. In the Overley grain, the smallest amounts of DON accumulated at the lowest moisture content. This research showed that triazoles applied at flowering in the field and grain stored at the lowest possible moisture content throughout storage are good recommendations to reduce DON.

Technical Abstract: Fusarium head blight, caused mainly by Fusarium graminearum Schwabe, results in major losses in wheat. In two separate field experiments, spikes of winter wheat cultivars ‘Overland’ (moderately resistant) and ‘Overley’ (susceptible) were sprayed at anthesis with the triazole fungicide Prosaro (prothioconazole + tebuconazole) or the strobilurin fungicide Headline (pyraclostrobin) or not sprayed. Following harvest, deoxynivalenol (DON)concentrations were monitored during 120 d of grain storage at 10 °C, 40% relative humidity, and 10%, 16%, or 20% grain moisture. In ‘Overland’, DON decreased significantly at P = 0.05 from an average of 3.6 to 3.0 µg g-1 in the check and decreased from 2.7 to 2.2 µg g-1 in the Prosaro treatment. DON did not significantly decrease (4.4–4.1 µg g-1) in the Headline treatment. DON concentrations did not differ between 16% (3.1 µg g-1) and 20% (3.0 µg g-1) grain moisture. In ‘Overley’, DON increased significantly from 3.1 to 3.6 µg g-1 in the check and from 2.9 to 3.5 µg g-1 in the Headline treatment, but remained the same at 2.2 µg g-1 in the Prosaro treatment. DON concentrations were not different between 16% (3.2 µg g-1) and 20% (3.1 µg g-1) grain moisture but were significantly lower (2.7 µg g-1) at 10% grain moisture. These results indicate that the effects of fungicides applied at anthesis in the field can impact DON concentrations through grain storage. Triazoles are recommended over strobilurins to achieve this extended postharvest protection from DON, and grain moisture during storage should be below the maximum safe level of 13.5% at 10 °C.