At this point in the growing season, many northern growers are checking fields for maturity as corn gets close to black layer – when starch, water and nutrients can no longer be translocated to the kernel. Now, the kernels are at the late dent kernel growth stage. Kernels will start to show a line between the hard starch layer and the inner milky white fluid. As the kernel matures, the hard starch layer progresses from the crown of the kernel all the way to the tip. This is when physiological maturity is reached.
“One of the questions we get around this time is if our corn isn’t at black layer, what will be the impact of killing frost,” said Nick Schimek, Pioneer Field Agronomist. “The severity of yield loss will depend greatly on the current growth stage of the crop and a few environmental conditions like low temperature and duration of that temperature. Sustained below freezing temperatures can halt ear development completely.”
To see how far along a field is, growers can pull back husks and look for dents in kernels. For dry grain, if fields are beginning to dent, growers can expect 20 to 25 days before their corn will reach black layer.
Kernel moisture loss during the drydown period is affected by air temperature, relative humidity and wind. Grain moisture at harvest affects the time and cost required to dry the grain to acceptable storage moisture levels, as well as grain quality. Wet grain can incur damage during combining, handling and drying. If grain quality is significantly reduced during harvest and drying, storage time is reduced and losses can occur. Consequently, choosing the optimum moisture for corn harvest is a critical management decision.