Maturing crops still could miss benchmarks

By Kent Thiesse

Despite above-normal temperatures in mid-September helping corn and soybeans, concerns remain it will not be enough to overcome late planting earlier this year. The 2019 corn and soybean crop have moved somewhat closer to reaching maturity.

The week of September 12 to 18 had an average daily temperature of 67.4 degrees, 5.8 degrees above normal, at the University of Minnesota Research and Outreach Center in Waseca. The growing degree unit accumulation during the week was 122.8, 38 percent above normal. Total GDUs were still about 5 percent below normal and well behind last year’s numbers. There are still some major concerns with crop development and maturity, especially in southwest Minnesota, northwest Iowa and eastern South Dakota, where corn and soybeans were planted 2-4 weeks later than normal.  

Based on the September 15 USDA Crop Report, it was estimated that only 59 percent of the corn crop in Minnesota had reached the “dent” stage, below the normal rate of 88 percent by that date. For most commonly grown corn hybrids, it takes approximately three to four weeks from the “early dent” stage until the corn reaches physiological maturity. It takes about two weeks for corn to reach maturity once the corn reaches the “hard or full dent” stage. 

Corn is considered safe from a killing frost once the corn reaches physiological maturity, which is when the corn kernel reaches the “black layer” stage. When the corn reaches black layer”, it is still usually at a kernel moisture of 28-32 percent. Ideally corn should be at 15-16 percent kernel moisture for safe storage in a grain bin. 

Even beyond reaching maturity, corn will require continued favorable weather conditions for natural dry-down of the corn in the field. Otherwise, farmers can expect to incur high drying costs this fall. It is likely that a high percentage of the 2019 corn crop will be stored in farm grain storage until the Spring and Summer of 2020. 

Soybeans are in a similar position. They normally require about two weeks to reach maturity once the leaves start turning colors. Based on the USDA Crop Report for September 15, only 47 percent of the soybeans in Minnesota were turning color, compared to a normal rate of 77 percent by that date. The normal first frost dates in southern Minnesota are from October 1 to 14.

Many areas of southern Minnesota and northern Iowa reported heavy rainfall, and even some hail and wind damage, during the week of September 8-14, with additional rainfall in some areas during the week of September 15-21. Most areas of southern Minnesota have received 4-6 inches of rainfall in September, with some areas of southwest Minnesota receiving 8-10 inches of rainfall, an unusual occurrence for the fall. Strong winds and hail in some locations also caused additional crop damage.

There will likely be some additional crop loss, along with potential delays in the 2018 corn and soybean harvest, in the areas that were most severely impacted by recent heavy rainfall. The corn and soybean fields near any rivers, streams or creeks, as well as in most other low lying, poorly drained portions of farm fields, were underwater. In many cases, fields in these same areas had been damaged or were not planted in 2019, due to damage from excessive rainfall earlier in the growing season.

Most farmers in southwest Minnesota, northwest Iowa, and eastern South Dakota are now dealing with completely saturated soil conditions, which could potentially delay harvest. The immediate impact has been for dairy and beef producers that are trying to harvest corn silage, as corn development is currently at the right stage for high quality silage harvest. In the hardest hit areas, it may take a week or longer of dry conditions for fields to be fit to resume silage harvest, and farmers may be forced to leave a portion of fields until the soils dry out. 

In many portions of this region, the corn and soybeans have not yet reached maturity, so there is some time for fields to dry out before full-scale grain harvest begins.

The crop damage and potential harvest problems are especially difficult for affected crop producers that are facing very tight profit margins in 2019. Farm operators in many portions of southern Minnesota, northern Iowa, and eastern South Dakota were already looking at reduced crop yield potential, due to poor growing conditions early in the growing season. 

Now, many producers are in a “wait and see” mode regarding corn and soybean harvest, hoping that the yields on the remaining crop acres are strong enough to offset yield losses from the heavy rains and flooded conditions. 

For additional information email Kent Thiesse, Farm Management Analyst and Senior Vice President, MinnStar Bank, Lake Crystal at  
To subscribe to BankWise for weekly Ag Lending News updates email Kristi Ploeger or call 651-789-3997. 

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