Reducing Fusarium Head Blight Vomitoxin Levels through Agronomic Practices

Vomitoxin levels caused by Fusarium graminearium are of great concern to Kentucky wheat producers and millers every growing season. Current agronomic practices to reduce vomitoxin (deoxynivalenol; DON) concentration in harvested grain include planting moderately resistant wheat cultivars and fungicide applications at beginning flowering (Feekes 10.5.1). However, some wheat producers that harvest at higher grain moistures and then dry grain to 13% moisture, have observed greater yields as compared to wheat harvested at 13% grain moisture. There are also reports from some milling companies that vomitoxin levels appear to be reduced when grain is harvested with a higher (20-25%) moisture content. Furthermore, there are numerous reports of in]furrow and at]planting phosphorus applications increasing grain yield and winter survival in areas with low soil phosphorus levels. However, research in Virginia found wheat forage yield was greater when seed]banded phosphorous fertilizer was applied to high soil test phosphorus soils. In another study the addition of phosphorus at planting, on soils with high soil test P levels, resulted in more plants per ft2, more tillers at Feekes 3 and Feekes 5 growth stages, and more heads at flowering. In Texas, grain yield was found to be greater when phosphorus was applied in-furrow with late wheat planting; however, with timely planting differences between grain yield were not found. More recently, Canadian researchers have indicated that in]furrow phosphorus applications can increase uniformity of heading on low phosphorus soils, which could reduce vomitoxin levels by protecting a higher percentage of heads with the Feekes 10.5.1 fungicide. Over the past three years (2017 to 2019), we have investigated whether additional agronomic practices, specifically harvesting at high (20-22%) grain moisture, in-furrow phosphorus (42 lbs P2O5/A) application at planting, and higher seeding rates (56 seed per ft2) can be implemented to reduce vomitoxin accumulation in soft red winter wheat. Our long-term goal for this project is to determine whether there are more sustainable and profitable agronomic management strategies for wheat production in Kentucky that reduce the risk of vomitoxin accumulation. Our objectives are to determine the effect of: i) harvesting wheat at different grain moisture contents (20 to 22% grain moisture and 13 to 15% grain moisture) on vomitoxin levels, test weight, and grain yield; ii) phosphorus applications at planting (0 lbs P2O5/A and 42 lbs P2O5/A) on the uniformity of wheat head emergence, flowering, and vomitoxin levels, test weight and grain yield; iii) seeding rating (35 seeds ft2 and 56 seeds ft2) on the uniformity of wheat head emergence, flowering, vomitoxin levels, and grain yield; iv) the time between harvest (at 20-22% grain moisture) and when the grain is dried to 12.5 to 13% moisture on vomitoxin levels; and v) the profitability of these production strategies.