Due to the favorable weather conditions we had in March of this year, the majority of our corn crop was planted “earlier” than in the past several years. Along with the earlier planting dates, favorable growing conditions and heat, some fields are approaching physiological maturity and beginning dry down.
When corn reaches the R6 reproductive stage—commonly called physiological maturity—it forms a visible black layer at the kernel base, indicating dry matter accumulation is complete and that the crops have reached full grain weight (≈30–35% kernel moisture). In South Carolina, this typically occurs about 55–65 days after silking (R1).
What to look for in the field
- Split a few representative ears: Examine the base of the kernels. If you see a darkened “layer” right where they attach to the cob—as shown in the photo below—that’s your black layer confirming physiological maturity.
🌽 Why this matters
- Harvest timing: Achieving black layer signals it’s safe to schedule harvest. You’ll avoid yield losses from ear sprouting or stalk lodging. Corn in SC is typically harvested when the moisture content has reached 25% down to 15.5%. Higher moisture content will result in increased drying costs; however, the risk of crop damage from hurricanes or other storms will be reduced.
- Irrigation management: Water use is no longer increasing yield post-black layer—so this is the ideal time to cut irrigation and conserve resources.
