Impact of agronomic practices onFusarium mycotoxin accumulation in maize grain

Abstract

In the Great Lakes region of North America, Gibberella ear rot (GER), caused by Fusarium graminearum, affects grain quality due to the accumulation of mycotoxins. GER severity is strongly influenced by environmental conditions; however, agronomic practices can also influence disease severity and mycotoxin accumulation. In this study, three separate small-plot experiments were conducted at Ridgetown, ON, Canada during 2019 and 2020 under an inoculated-misted system to determine Fusarium mycotoxin accumulation as affected by: (1) plant population density; (2) in-row-plant developmental variability; and (3) the effect of integrated Bt refuge genetics. In this study, DON concentrations were at least 49% higher in maize at 113,600 plants/ha compared to 79,000 plants/ha. Moreover, mycotoxin accumulation was higher in plants that were delayed developmentally in the crop row; total DON concentrations were at least 310% higher in late silked plants adjacent to early silked plants. Results of the plant population density and in-row-plant developmental variability suggest that the main driver for mycotoxin accumulation was stress induced by plant competition rather than environmental conditions; this highlights the importance of avoiding plant competitive stress as a strategy to reduce the risks of mycotoxin accumulation. In this study, there was no statistical difference in DON accumulation between the Bt component and the non-Bt component in each of the four hybrids tested; however, there was evidence that hybrids varied in susceptibility, including the Bt and non-Bt components that were paired commercially in a bag of seed maize. Reducing mycotoxins in maize requires integrated management, which includes agronomic considerations. These results indicate that mycotoxins are favoured with high plant populations and plant-to-plant variability in the row, especially in susceptible hybrids.

Mycotoxins and Crop Yield in Maize as Affected by Irrigation Management and Tillage Practices

“…Apart from conducive environmental conditions, maize contamination with mycotoxins is influenced by agronomic management practices [17,18]. In a recent study on the impact of agronomic practices on Fusarium mycotoxin accumulation in maize grain, the main driver for mycotoxin accumulation was stress induced by plant competition rather than environmental conditions [19]. Selecting varieties adapted to the growing area and resistant to fungal diseases can help to reduce mycotoxin production in the field [20].…”

Planting time and seeding rate impact insect feeding, ear rots, and forage nutritive value in silage corn

“…Studies by Eli et al. (2022) and Parsons and Munkvold (2012) also corroborated the importance of varying planting dates to avoid conditions favorable for fungal infections during the silking window. Moreover, in our study, it was observed that the silage corn from mid‐planting had a more severe insect feeding injury as compared to early and late planting.…”

“…Out of various crop management decisions, planting date is critical as it influences the exposure of silage corn at a particular stage and the extent of its susceptibility to insect injury and fungal infections (Eli et al., 2022; Pfordt et al., 2020). The planting date determines the time of corn silking (most susceptible stage to stresses) and the environmental conditions around it, which influence the type and extent of ear infections and mycotoxin accumulation (Krnjaja et al., 2022; Parsons & Munkvold, 2012).…”

“…Plant density, as determined by the seeding rate, influences the microclimate within a crop field and the ability of plants to adapt to specific growing conditions, as well as the severity of insect injury and fungal infections (Eli et al., 2022). Plant densities have increased across the United States due to increasing stress tolerance in corn hybrids (Williams et al., 2021) and have resulted in greater grain yields, especially in high‐yielding environments (Assefa et al., 2016).…”

“…These later plantings in silage corn might provide less time for the ear rot fungi to produce and accumulate mycotoxins. This may not be true if the delayed planting results in a favorable environment for fungal infection while also exposing the plant to lepidopteran insect feeding around silking (Eli et al., 2022). However, research is lacking regarding the impact of planting time and plant density on silage corn response to biotic stresses and eventually dry forage yield, nutrient concentration, and digestibility.…”