Evaluating corn and soybean stands and easy management tools

Assess the effects of your management decisions on plant stands.

This is a great time to get out in the fields and see how well crops emerged. Determining the plant population for corn and soybeans at this time of year will allow you to evaluate management decisions made at planting as well as identify any emerging concerns from weeds, insects or diseases.

When estimating the population:

  • Measure 1/1,000 of an acre. See table below.
  • Count the number of plants in the measured area.
  • Count at least six representative places across the field.
  • Multiply the average number of plants by 1,000 to calculate the final plant population per acre.

Feet of row representing   1/1,000 of an acre at different row widths

Row spacing

Row length

7 inch

74 feet, 9 inches

10 inch

52 feet, 3 inches

15 inch

34 feet, 10 inches

20 inch

26 feet, 2 inches

30 inch

17 feet, 5 inches

Iowa State University Extension Corn Field Guide
Iowa State University Extension Soybean Field Guide, 2nd edition

Here is an example: To determine the stand in a field of corn planted in 30-inch rows, measure 17 feet 5 inches and count the number of viable plants. Do this in six locations in the field. Select locations that are representative of the stand in the field. Calculate the average of the counts and multiply by 1,000 (e.g., 30 + 31 + 29 + 33 + 30 + 32 = 30.8 x 1,000 = 30,800 plants per acre).

While walking the field, take note of any weed, insect or disease problems. If there is a problem that is not easily identified, take a picture. This can be emailed to MSU Diagnostics Services to aid in problem identification. Email pictures to .(JavaScript must be enabled to view this email address).

Corn and soybean seedling disease can be a cause for poor stands. Fungi including Rhizoctonia solani, Fusarium species and fungal-like organisms such as Pythium species can cause damping off, which impact seeds before or as they are germinating, or after the seedling has emerged. Martin Chilvers, MSU Department of Plant Pathology, is working on a multi-year study to identify the diseases that impact corn and soybean stands. He has summarized the results from 2011 in a May 2012 MSU Extension News article, Multiple Pythium species associated with soybean and corn seedling disease in Michigan.

Seedlings
Soybean seedlings with damping off symptoms

This study will continue in 2012 and we need your help in locating both corn and soybean fields with damping off. If you know of a field with seedling disease, please email .(JavaScript must be enabled to view this email address) or call him at 517-898-3049.

Determining the stand in corn and soybean fields can help fine-tune planting programs and identify weed, insect and disease problems. Take time today to implement this easy tool.

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