Is your wheat ready for swathing or an application of glyphosate?
The optimum time for either is right at or just after physiological maturity of the crop, At physiological maturity, the crop has the maximum kernel dry weight and no additional dry matter will be deposited in the grain.
Jochum Wiersma, University of Minnesota Extension wheat specialist, says kernel moisture percentage at physiological maturity is relatively high and can vary from 20 to 40%.
"Research has shown that swathing just before physiological maturity does not harm the grain yield or quality. This practice, however, is not recommended when using glyphosate as a pre-harvest tool," he says.
There are two visual indicators that can be used to determine whether the crop has reached physiological maturity.
The loss of green in the kernel and the appearance of a dark layer of cells or pigment strand along the crease of the wheat kernel. Kernels in the same spike will reach physiological maturity at different times with the middle of the head maturing first.
The loss of green from the peduncle and glumes. If the peduncle just below the head becomes straw-colored, transportation of water and nutrients to the head has been cut off and the crop has reached physiological maturity.
Source: U of M