Ag Weather Forum

Variable Late-September Crop Prospects

Mike Palmerino
By  Mike Palmerino , DTN Senior Ag Meteorologist
Graphic cutline: U.S. corn denting rate, at 79%, is the slowest since 2009. (DTN ProphetX graphic)

Corn and soybean development remains well behind normal in most of the Midwest and Northern Plains. Latest crop reports indicate corn and soybean development is running about eight to 15 days behind normal in the western Midwest and 10-15 days behind normal in the eastern Midwest. The corn denting rate is the slowest in 10 years, going back to 2009, at 79% dented, and the maturity rate of corn is just over half the average rate -- 29% versus 57% average. In soybeans, the percentage of the crop dropping leaves is only 34% compared with an average of 59%.

Soil moisture has shown improvement during the past week in the dry areas of Illinois and southeast Iowa. Soils have turned drier in Indiana and Ohio. This is likely reflected in the 2-percentage-point drop in corn and soybean ratings in Ohio. Elsewhere in the major producing states, crop ratings were mostly unchanged except for a 4-percentage-point rise for corn in Illinois and 3-percetange-point rise in Minnesota. On the other side of the soil moisture coin, the profiles are brim-full saturated -- in the Northern and Central Plains and the western Midwest.

The Midwest forecast calls for near- to above-normal temperatures during the next 10 days. Rainfall looks to be near- to above-normal west and near- to below-normal east. Eastern Midwest areas will have favorable conditions, with a warm-and-dry pattern benefiting row crops in their progress toward maturity. The western Midwest will have seasonal temperatures; however, moderate-to-heavy rain is indicated for much of this sector, with the potential for a new round of flooding due to rain falling on saturated soils.

In the northwestern Plains, cold air pooling over Western Canada during the next few days will potentially lead to a growing season-ending freeze in the western Prairies during the next week. Some of this cold air is expected to move into the eastern Prairies and North Dakota during the middle of next week. Some crop damage to immature canola in the Prairies and immature corn and soybeans in North Dakota cannot be ruled out.

Southern hemisphere conditions are not as favorable for early-season field work as they were a year ago. In central Brazil, very hot and dry weather in central Brazil has prevented early planting of soybeans, except in any fields that might be irrigated. Scattered light-to-moderate showers and thunderstorms, with a break in the heat, are indicated during midweek. However, this will likely not be enough rain to initiate widespread planting. The remainder of the seven-day period is expected to feature dry conditions or just a few light showers, along with near- to above-normal temperatures.

Sea surface temperatures in the eastern equatorial Pacific Ocean for the first half of September have dropped to minus 0.9 degrees Celsius. This is down from the minus 0.3-degree-C departure observed in August. These are levels indicative of La Nina conditions although there is no mention of this in any official government reports at this time. If sea surface temperatures remain below normal we could see concerns over dryness in Argentina during the Southern Hemisphere growing season. Meanwhile, the Southern Oscillation Index (SOI), the Pacific Ocean barometric analytic detail tracked by the Australia Bureau of Meteorology, is at a weak El Nino value; its Sept. 24 90-day reading was at minus 8.57.

Michael Palmerino can be reached at



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