The Effect of Pre-harvest Glyphosate on Quality of Milling Oats
Applying glyphosate or swathing at or above 50% SMC has negative effects on seed quality and therefore end use capabilities. When treatments were swathed at or above 60%, there is a risk that beta-glucan levels can drop below 3%, the percentage groat will decline, which ultimately impacts milling yield and increases the amount of wastage during the milling process. Compared to direct combining without glyphosate, there appears to be no effect on oat quality when glyphosate is applied ≤40% SMC. Across all site years, oat cultivar did not have as much of an impact as the other two factors (i.e. seeding rate and harvest method) did. Increasing seeding rates resulted in a reduction in SMC at harvest, lower TKWs, and softer groats. Overall Pinnacle was less affected by changes in harvest method in regards to percent plump and thin kernels. CDC Dancer had an increase in thin kernels and a decrease in plump kernels when plots were swathed. Using glyphosate as a harvest method has no more of a negative impact than swathing on oat yield or seed quality, regardless of seeding rate or cultivar used. It is plausible that pre-harvest glyphosate had a greater impact on perennial weed control than in-season herbicides used. Dandelion populations were generally higher when a post-emergent herbicide was used alone. View the PDF below for final report.