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Mapping Out September Crop Progress in Illinois

September brought varying amounts of precipitation to the state of Illinois.

Illinois crop progress has lagged behind the five-year average pace all season, thanks in part to drawn out planting. Challenges to make up for lost time continued into September for the state's corn and soybean crops.

Here's a five-week breakdown of the weather and how it affected corn and soybean progress throughout the Prairie State.

Week 1: September 1-7

The month started off with dry conditions in the northern half of the state. On September 3, over 37% of the state was abnormally dry and 11.71% of the state was experiencing moderate drought.

Map of Illinois drought conditions on September 3, 2019
David Miskus

On September 1, 82% of the Illinois corn crop was at dough stage compared with a five-year average of 97%, according to the September 3 USDA Crop Progress report. Just 46% of the corn crop had dented compared with a five-year average of 76%. Only 2% of the corn crop was rated mature. At the same time a year ago, in 2018, 32% of Illinois corn was mature. The five-year average is 18%.

Illinois corn conditions were reported as follows:

  • Very poor: 4%
  • Poor: 15%
  • Fair: 35%
  • Good: 40%
  • Excellent: 6%

Soybean progress also lagged behind the average pace to start the month. The first USDA Crop Progress report of September said 95% of the soybean crop was blooming compared to a five-year average of 100%. Soybeans setting pods were at 84% compared with the 97% five-year average.

Illinois soybean conditions were reported as follows:

  • Very poor: 4%
  • Poor: 13%
  • Fair: 37%
  • Good: 3%
  • Excellent: 7%

By the end of the first week of September, northern counties in Illinois recorded several inches of rain, while farmers in the southern part of the state recieved a few tenths of an inch or less.

Illinois-September-Week1-Precipitation-Totals-Map
Iowa Environmental Mesonet

Crops in the northern half of the state saw fewer growing degree days (GDDs) than average for the first week of September this year. Farms in far southern Illinois had as many as 15 GGDs above average for the first week of the month.

Map of Illinois GDDs week 1 of September 2019
Iowa Environmental Mesonet

Week 2: September 8-14

While some parts of Illinois got welcomed precipitation going into the second week of September, dry conditions persisted in many northern counties. More than one-third of the state was abnormally dry, and 11.71% of Illinois was in moderate drought to start the week.

Map of Illinois drought conditions on September 10, 2019
David Miskus

On September 8, 88% of the Illinois corn crop was at dough stage compared with a five-year average of 99%, according to the September 9 USDA Crop Progress report. Just 53% of the corn crop had dented compared with a five-year average of 87%. Only 8% of the corn crop was rated mature. At the same time a year ago, in 2018, 53% of Illinois corn was mature. The five-year average is 35%.

Illinois corn conditions were reported as follows:

  • Very poor: 6%
  • Poor: 15%
  • Fair: 41%
  • Good: 34%
  • Excellent: 4%

Soybean progress continued behind the average pace, too. The second USDA Crop Progress report of September said 90% of the soybean crop was setting pods compared to a five-year average of 99%.

Illinois soybean conditions were reported as follows:

  • Very poor: 6%
  • Poor: 13%
  • Fair: 40%
  • Good: 36%
  • Excellent: 5%

Week two brought more varied precipitation to the state. Counties on the northern Illinois-Wisconsin border recorded between 5 and 8 inches of precipitation. Meanwhile, farms in the southern two-thirds of the state saw rain totals less than an inch.

Map of Illinois precipitation totals for the second week of September 2019
Iowa Environmental Mesonet

Above average temperatures statewide, by as much as 8 degrees, helped crops continue progress toward maturity.

Map of Illinois temperature departures for week 2 of September 2019
Iowa Environmental Mesonet

Temperatures above average meant another week of above average GDDs for Illinois crops.

Map of Illinois GDDs week 2 of September 2019
Iowa Environmental Mesonet

Week 3: September 15-21

While warmer temperatures gave crops Illinois crops additional GDDs as they continued to play catch up on the season, the higher temperatures caused abnormal dryness to appear in the southern half of the state for the first time in September. The drought monitor map from September 17 indicates abnormally dry acreage increased to 38.16% of the state, but the more severe category of moderate drought acres saw a decline to 5.79%.

Map of Illinois drought conditions on September 17, 2019
Eric Luebenhusen

On September 15, 94% of the Illinois corn crop was at dough stage compared with a five-year average of 100%, according to the September 16 USDA Crop Progress report. Just 67% of the corn crop had dented compared with a five-year average of 94%. Only 14% of the corn crop was rated mature. At the same time a year ago, in 2018, 72% of Illinois corn was mature. The five-year average is 53%.

Corn harvest officially started in the third week of September for a small number of Illinois farmers. As of September 15, 1% of the state's corn had been harvested. In 2018, 11% of Illinois' corn had been harvested by this point in the growing season. The five-year average is 6%.

Illinois corn conditions were reported as follows:

  • Very poor: 5%
  • Poor: 14%
  • Fair: 40%
  • Good: 35%
  • Excellent: 6%

Soybean progress also lagged behind the average crop progress pace. The third USDA Crop Progress report of September said 93% of the soybean crop was setting pods compared to a five-year average of 100%. Soybeans dropping leaves were at just 3% compared with the 33% five-year average.

Illinois soybean conditions were reported as follows:

  • Very poor: 8%
  • Poor: 14%
  • Fair: 36%
  • Good: 36%
  • Excellent: 6%

For the second week in a row, precipitation varied widely across the state. Northern Illinois farms got up to 3.54 inches of rain, and southern Illinois farms saw little, if any, moisture.

Map of Illinois precipitation totals for the third week of September 2019
Iowa Environmental Mesonet

Week three again brought statewide above average temperatures.

Map of Illinois temperature departures for week 3 of September 2019
Iowa Environmental Mesonet

Another week of above average GDDs was welcomed by farmers eager to see their corn and soybean crops achieve maturity.

Map of Illinois GDDs week 3 of September 2019
Iowa Environmental Mesonet

Week 4: September 22-28

Dry conditions grew more severe in southern Illinois in the fourth week of September. Just shy of 30% of the state was abnormally dry, and 6.31% of the state was in moderate drought as of September 24.

Map of Illinois drought conditions on September 24, 2019
Iowa Environmental Mesonet

On September 22, 97% of the Illinois corn crop was at dough stage compared with a five-year average of 100%, according to the September 23 USDA Crop Progress report. Just 77% of the corn crop had dented compared with a five-year average of 97%. Only 26% of the corn crop was rated mature. At the same time a year ago, in 2018, 84% of Illinois corn was mature. The five-year average is 71%.

Illinois farmers made very slow corn harvesting progress in the fourth week September. As of September 22, 2% of the state's corn had been harvested, up just 1% from the preivious week. In 2018, 26% of Illinois' corn had been harvested by this point in the growing season. The five-year average is 16%.

Illinois corn conditions were reported as follows:

  • Very poor: 4%
  • Poor: 14%
  • Fair: 37%
  • Good: 39%
  • Excellent: 6%

Soybean progress also lagged behind the average crop progress pace. The fourth USDA Crop Progress report of September said 14% of the soybean crop was dropping leaves compared to a five-year average of 56%. 

Illinois soybean conditions were reported as follows:

  • Very poor: 4%
  • Poor: 14%
  • Fair: 39%
  • Good: 36%
  • Excellent: 7%

Rain fell across the state during the fourth week of September. Totals ranged from 3.75 inches in the northeast to under a quarter inch in central Illinois.

Map of Illinois precipitation totals for the fourth week of September 2019
Iowa Environmental Mesonet

Another week of above average temperatures generated an above average number of GDDs and kept crops progressing toward the finish line.

Map of Illinois temperature departures for week 4 of September 2019
Iowa Environmental Mesonet

Map of Illinois GDDs week 4 of September 2019
Iowa Environmental Mesonet

Week 5: September 29-30

On September 29, 85% of the Illinois corn crop was dented compared with a five-year average of 99%, according to the September 30 USDA Crop Progress report. Only 40% of the con crop was rated mature. At the same time a year ago, in 2018, 94% of the corn crop was rated mature. The five-year average for the state is 86%. Illinois farmers have harvested 4% of thes state's corn crop, the USDA said. Last year, corn harvest was 45% complete at this time.

Illlinois corn conditions were reported as follows:

  • Very poor: 5%
  • Poor: 15%
  • Fair: 33%
  • Good: 41%
  • Excellent: 6%

Soybeans in Illinois continue to mature behind the five-year average pace. The fifth USDA Crop Progress report of the month said 41% of the soybean cop was dropping leaves compared with a five-year average of 76%. Farmers in the state started harvesting soybeans at the end of the month. USDA reported soybean harvest is 1% complete, 21% behind the five-year average harvest pace.

Illinois soybean conditions were reported as follows:

  • Very poor: 5%
  • Poor: 14%
  • Fair: 37%
  • Good: 38%
  • Excellent: 6%

Heavy rain fell in central Illinois to close out the month of September. More than 3 inches of precipitation were recorded in the middle part of the state.

Map of Illinois precipitation totals for the fifth week of September 2019
Iowa Environmental Mesonet

The month of September also ended on a warmer than average note for nearly the whole state.

Map of Illinois temperature departures for week 5 of September 2019
Iowa Environmental Mesonet

September 2019 Overview

In summary, Illinois varied widely between the northern half and the southern half during the month of September.

Precipitation totals peaked at 16.62 inches for the month in the northwest, while the southern tip of the state saw shy of an inch.

Illinois precipitation totals for September 2019
Iowa Environmental Mesonet

Rain totals in the northern half of the state were above average while the southern part of the state got less rain than average.

Map of Illinois precipitation departure for month of September 2019
Iowa Environmental Mesonet

In other words, the northern third of the state saw at least 200% of average rainfall during the month of Septmeber.

Illinois precipitation percentage map for September 2019
Iowa Environmental Mesonet

Overall, the month of September was warmer than average as well.

Illinois-September-Average-Temperature-Map-2019
Iowa Environmental Mesonet

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