Fundamentally Speaking

1st IL Freeze Date vs. Corn Maturity, Yields

It appears that one of the reasons why the USDA is expected to boost its 2013 row crop yield estimates in the upcoming crop production report on November 8 is the first hard freeze in much of the Midwest coming well after the first normal fall frost date.

Recall that both U.S. corn and soybeans got planted late and this led to concern that a large percentage of both would be immature by the time the first normal fall freeze dates arrived in much of the Corn Belt.

Such was not the case as the first freeze date came in mid-October or later allowing almost all of the U.S. corn and soybean plants to reach full maturity.

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This should lead to both corn ear and soybean pod weights becoming a little heavier with soybean yields also helped by late September rains.

We have tried to quantify the impact of a later or earlier than normal fall freeze on yields but the evidence is mixed.

The accompanying graphic shows the percent change in the Illinois corn yield from the September to the final report and the percent maturity of that states corn crop as of September 29 vs. the number of days after September 1 that DeKalb, IL recorded its first 28 degree Fahrenheit or lower reading.

In looking for large upward revisions, 1992 and 1994 top the list at 14.6% and 13.0% respectively as both seasons saw record high final corn yields.

1992 was a late maturing season with only 53% of the Illinois crop mature as of September 29 but the first 28 degree day came October 17, or 47 days after September 1 and that is below the average first 28 degree date for that locale of October 23.

1994 on the other hand had a very late first fall freeze that year of November 19 or 80 days after September 1.

Of course, the fact that the states corn crop was 95% mature as of September 29 implies limited benefit from the extended growing season that year.

The study period going from 1981 to 2012 shows the earliest fall freeze occurring in 1991 just 27 days past September 1 but the crop was almost all mature that year.

(KA)

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