Reducing Fusarium Head Blight Vomitoxin Levels through Agronomic Practices-Year 3

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) levels include planting moderately resistant wheat cultivars and fungicide applications at beginning flowering (Feekes 10.5.1). However, we are investigating if additional agronomic practices, specifically harvesting at high (20]22%) grain moisture and in]furrow phosphorus (42 lbs/A) application at planting, can be implemented to reduce vomitoxin accumulation in soft red winter wheat. Some wheat producers that harvest at higher grain moistures and dry grain to 13% moisture have observed greater yields as compared to wheat harvested at 13% moisture. There are also reports from some milling companies that vomitoxin levels appear to be reduced when grain is harvested at grain moisture content from 20]25%. Additionally, some studies of in]furrow phosphorus applications have indicated that there is potential for increased winter survival and grain yields in high phosphorus soils. In]furrow phosphorus has also been shown to reduce vomitoxin levels by increasing uniformity of heading which has led to better fungicide efficacy for applications made at Feekes 10.5.1 in low phosphorus soils. The objectives of this study are to investigate the effect of: i) harvesting wheat at different grain moisture contents on vomitoxin levels; and ii) phosphorus applications at planting on the uniformity of wheat head emergence, flowering, and vomitoxin levels. The proposed work will support the third (final) year of this project. In the first and second year of the project, wheat was planted in October and November to account for the range of typical wheat planting in Kentucky. Treatments include harvest timings where wheat harvested at high (20]22%) and low (13]15%) grain moisture; in]furrow phosphorus applications (0 lbs P/A or 42 lbs P/A); two wheat cultivars (a cultivar with moderate resistance to FHB and a cultivar susceptible to FHB); and two seeding rates 35 seeds per square foot and 56 seeds per square foot. In 2017, the number of Fusarium damaged kernels in the harvested grain was less for the grain harvested at 20]22% grain moisture than when grain was harvested at 13]15%grain moisture. However, the high moisture wheat had significantly higher DON concentrations than the normal harvested wheat. The in]furrow phosphorus treated plots had a higher percentage of FDK as compared to the plots with no additional phosphorus, however there was no difference in the DON concentrations between the phosphorous treatments. The 2018, high (20] 22%) moisture wheat was harvested on June 8th and June 15th, respectively, for the October and November plantings. The normal moisture wheat (13]15%) will be harvested in late June, due to frequent, heavy rain events that have delayed harvest. Grain yield, FDK, DON concentrations, flowering uniformity, and number of kernels infected with Fusarium graminearum will be measured.