Projecting the Timeline for Corn Harvest

BY Dairyland Seed Agronomy Team

As the corn crop across our footprint is in the grain fill (or reproductive stages), a common conversation topic is when the corn crop will mature and when harvest will begin. Some areas may have the opportunity to capitalize on early delivery of grain corn and understanding the timeline between tassel and physiological maturity can help determine if that may be a viable option for your operation.

Corn matures approximately 55 to 60 days after tasseling. There are many stages in the maturation process. Knowing when tasseling occurs can help estimate when corn will mature, so be sure to note the date tasseling.
The progression of the milk line and black layer development are important to irrigation scheduling and application of pre-harvest herbicides. Yield could be reduced if you terminate irrigation or apply a harvest aid too early.
It takes approximately 20 days for the milk line to progress from kernel tip to base. For example, if the milk line is halfway down the kernels, it will take another 10 days to reach physiological maturity; so the field needs continued irrigation and a delay in harvest aid application for 10 more days.
Black layer forms when the hard starch layer reaches the kernel base which signifies physiological maturity. The black layer cuts off water and dry matter transfers into the kernel. At this stage, kernels have a moisture content of about 28 to 35 percent.

DRY DOWN FOLLOWING MATURITY

Kernel drying that occurs following black layer is entirely due to evaporative moisture loss.
The corn drydown rate is tightly linked to daily growing degree unit (GDU) accumulation. In general, drying corn from 30 percent down to 25 percent moisture requires about 30 GDUs per point.
Drying from 25 percent to 20 percent requires about 45 GDUs per point (Lauer, 2016).
GDU accumulation and drydown rates are greatest during the earlier, warmer part of the harvest season and decline as the weather gets colder.
By November, GDU accumulation rates are low enough that little further drying will typically occur.

If you have any questions regarding corn development stages please contact your local Dairyland DSM or Regional Agronomist.