We saw it on Crop Tour and USDA’s weekly crop progress data continues to confirm that large portions of the U.S. corn and soybean crops need extra weeks on the end of the growing season to reach maturity. As of Sept. 1, USDA said 19% of the corn crop (17.1 million acres) hadn’t reached dough stage yet and 14% of the soybean crop (10.7 million acres) wasn’t yet setting pods. That was 12 percentage points and 10 points behind the respective five-year averages for the beginning of September. Those acres will need well into October to reach full maturity. That’s a lot of acres that are at risk of an early or even normal end to the growing season.
Most at risk are the northern states, where the normal first freeze date is earliest. The non-podded soybeans are most at risk, as they are simply running out of daytime hours required to turn flowers into pods and fill. The late-maturing corn can push to the finish line if it has enough growing degree units. The clock is ticking on these portions of both crops.
The map above shows the historical median date of the first fall freeze (32°F or lower). Though most agronomists believe it takes at least two hours of temps between 24°F and 28°F to kill crops, fields exposed to temperatures in the 30s, even if not sub-freezing, experience “shock” that slows development.