Impact of post-anthesis rainfall, fungicide and harvesting time on the concentration of deoxynivalenol and zearalenone in wheat

Abstract

Field experiments were conducted to identify the impact of post-anthesis rainfall on the concentration of deoxynivalenol (DON) and zearalenone (ZON) in harvested wheat grain. Winter wheat plots were inoculated with Fusarium graminearum at stem extension (GS31) and prothioconazole was applied at mid-anthesis (GS65) to split plots and plots were subsequently mist irrigated for 5 days. Plots were either covered by polytunnels, irrigated by sprinklers or left as non-irrigated uncovered control plots after medium-milk (GS75). Plots were harvested either when ripe (GS92; early harvest) or three weeks later (late harvest). Fusarium head blight (FHB) was assessed each week from inoculation. At harvest, yield and grain quality was measured and grains were analysed for DON and ZON. Differences in rainfall resulted in contrasting disease pressure in the two experiments, with low FHB in the first experiment and high FHB in the second. Difference in FHB resulted in large differences in grain yield, quality and mycotoxin content. DON concentration was significantly (P < 0.05) higher in irrigated compared to covered and control plots in the first experiment, whereas in the second experiment, DON was significantly (P < 0.05) higher in the covered plots compared to the control and irrigated plots. ZON concentration was significantly (P < 0.05) higher in irrigated plots in both experiments. Later harvesting resulted in an approximate fivefold increase in ZON in the first experiment, but was not significantly different in the second experiment. Prothioconazole significantly (P < 0.05) reduced DON in both experiments, but gave inconsistent reductions to ZON. This is the first report to show that the post-anthesis rainfall can significantly increase ZON in wheat, which can increase further with a delayed harvest but may be significantly reduced with the application of prothioconazole. Importantly, in the absence of moisture late season, ZON remains at very low concentrations even when wheat is severely affected by FHB.

Impact of pre-harvest rainfall on the distribution of fusarium mycotoxins in wheat mill fractions

“…All analysis showed significant interactions (P<0.05). Prior to the treatments the DON concentration in mill fractions were as reported previously for wheat harvested in the UK in 2005 (Kharbikar, Dickin, & Edwards, 2015) with lower DON concentrations in the SRF and more in the bran and offal fractions ( Figure 2a). There was little change in the concentration of DON in cleaned grain, SRF and bran but a significant reduction (40%) in DON in the offal fraction occurred after repeated conditioning.…”

DON content in oat grains in Norway related to weather conditions at different growth stages

“…We detected an increased DON content in oat grains harvested from fields with cool and moist weather during this period. The importance of moisture post-flowering has also been reported alone (Cowger et al 2009;Andersen et al 2015;Kharbikar et al 2015) and in combination with warm weather (Franz et al 2009). No association was detected between the DON accumulation and rain during late milk and dough development in our study, although a positive association was detected between DON and precipitation during milk development.…”

Temporal dynamics, population characterization and mycotoxins accumulation of Fusarium graminearum in Eastern China

“…In a previous article, we found a clear relationship between higher precipitation and high levels of DON and ZEN56. Some recent publications have suggested that environmental conditions, especially moisture in the form of rainfall or relative humidity, are associated with higher DON and ZEN accumulation505758.…”