There's is still hope of corn reaching maturity in South Dakota before a hard frost says Laura Edwards, SDSU Extension climate field specialists.

"To determine how close the corn crop is to maturing (reaching black layer), we used the Useful 2 Usable Corn Growing Degree Day (GDD) tool," she says. "This tool allows us to look at a few possible scenarios of planting dates and maturities for every county in the state, with climate data updated on a daily basis. We first considered an early planting date of April 28th (when about 10% of South Dakota corn acres had been planted), and then a late planting date of May 27th (when about 90% of the state's corn acres had been planted).

Freeze Worries Fade For 90-day Corn In South Dakota

Edwards and her SDSU Extension colleagues also considered two maturities, 90 day and 100 day. These hybrids and planting dates were used for all counties of the state, and the Corn GDD tool calculated the probability a hard freeze (28 degrees F) before reaching black layer, using historical freeze dates of the last 30 years.

The maps show the results. Yellow shaded areas are the lowest risk of frost damage this fall, with 30% or less probability of freezing before black layer. The green shaded counties are of moderate risk, in the 30-60% range of freezing before black layer, and the red shaded counties are in the highest risk areas, with more than 60% probability of freezing before black layer.

Maps show the probabilities of reaching a hard freeze before black layers. Yellow is the lowest risk. Red is the highest. Source: SDSU Extension

"The results show that 100-day maturity will be at high risk statewide, if it was planted late. Corn that was planted in most of the western counties is at moderate to high risk, if they have not already been impacted by the hard freeze a couple of weeks ago. The southeastern counties are at the lowest risk overall for reaching black layer before freeze,' she says.

Corn has the ability to accelerate to maturity in the latter part of the season, Edwards notes. That ability to accelerate development is not accounted for in the GDD tool.

"The current long term weather forecast doesn't show any real indication of a hard freeze occurring, so there is reason to be a little more optimistic for the fall corn harvest," she says.

Source: SDSU Extension