February 05, 2023

McLean corn yield survey finds high variability

BLOOMINGTON, Ill. — An annual yield survey by First Mid Ag Services estimates McLean County corn to average 209.46 bushels per acre, slightly below the five-year average.

Illinois’ top corn-producing county averaged 205.7 bushels per acre last year and 201.8 in 2020. The McLean County record was 229.3 set in 2018 and the five-year average is 211.1 bushels per acre, according to the U.S. Department of Agriculture.

The yield estimate is based on 1,620 samples from 162 locations. The samples were taken on managed farms from every township in McLean County by nine First Mid farm managers, according to Michael Rhoda, First Mid Ag Services assistant vice president, farm manager and survey coordinator.

Sample yield estimates were highly variable, ranging from 138 to 276.4 bushels per acre.

The survey found 65% of the locations returned a yield estimate over 200 bushels per acre, compared to 70% in 2020 and 93% in 2021.

The majority of the samples used for this estimate were taken the second week of August.

Rows around and ear length were found to be slightly above average and ear population was also above average. With the dry conditions it was estimated the kernel weight to be a bit lighter than average.

Here are other observations from McLean County’s in-field yield survey.


Planting in 2022 was later than the five-year average. There were planting windows in April, but approximately 68% of fields sampled were planted in May.

Following planting there was a hot and dry spell throughout June where there were highs of 97 degrees. The June weather helped the plant health, but may have hindered the May-planted corn.

There was a hailstorm on July 24 that was very severe in isolated areas of northeast McLean County.

In July, McLean County had good growing weather with temperatures staying in the mid 80s and a few rains. August was mostly dry with a needed shower August 19 that helped finish the crop out.

Planting Date

Planting dates for the samples taken ranged from April 27 through May 17 with an average planting date of May 7.

When comparing the April-planted corn to the May-planted corn it was estimated there was no statistical difference in yield, but the April-planted kernels are expected to gain a little more weight.


Due to the majority of the farms getting the crop in with good to superb soil conditions, the emergence was good. Fields planted in April came up more uneven compared to May-planted stands, which resulted in approximately 8% fewer ears per acre.

“We do not think this equates to less yield compared to May plantings due to a higher expected kernel weight and less tip back in the April-planted fields,” Rhoda said.

Final ear populations of about 32,500 ears per acre were recorded. This estimate was a little higher than the five-year average estimate.

The average plants per acre were on average with approximately 33,200 plants per acre recorded.

Fungicide Application

Each year, First Mid farm managers track samples sprayed with fungicide. Application typically occurs during the R1 timeframe between tassel and brown silk.

This year, 90% of samples received a fungicide, much greater than the 76% sprayed last year.

While pulling checks, disease pressure seemed to be little to none in both sprayed and non-sprayed fields. There was minimal to no tar spot.

A 3.9-bushel advantage is estimated on farms that were sprayed.


Anhydrous applications were able to be completed either last year or early this spring. There were some N deficiencies noted, but it was attributed more to the lack of water.

Firing of lower leaves can be attributed to the long periods of minimal moisture more so than running out of nitrogen. No real issues were noted.


Plant health was a non-issue throughout most of the season. The average stalk quality rating is 9.10 on a scale from 1 to 10.

Some plants had lodged a little and there were a couple of fields that had hail damage.

The lowest estimated yield was a hail-damaged field. As the corn move towards harvest, stalk qualities should be monitored because anthracnose and other diseases could still have a negative effect on stalk quality.

Tom Doran

Tom Doran

Field Editor