Answers are from the Indiana certified crop adviser panel: Gene Flaningam, Flaningam Ag Consulting, Vincennes; Carl Joern, Pioneer, Lafayette; Greg Kneubuhler, G&K Concepts, Fort Wayne; and Dan Quinn, Purdue Extension corn specialist.

 

My corn stand is looking thin in several fields. Last year, I had some poor stands that I did not replant, and I paid for it in the fall. What factors should I consider for a replant?

 

Flaningam: Consider the current plant date versus replant date. The current yield potential of the existing plant stand is very important. Thin stands will provide less yield potential, less weed control and less return on investment. Future short-term weather conditions must be favorable to have a successful replant stand.

 

Joern: When evaluating a field with large, irregular stand gaps, making a replant decision becomes much more challenging. The key is to gather representative stand counts to assess the current trajectory of the field given its reduced population. This data should then be compared to the expected outcome if you were to terminate the existing stand and replant.

 

In general, corn planted within the traditional window holds higher yield potential than later-planted corn, which is typically the case with replant decisions. If your stand count is in the teens, it may be worth considering a complete replant. However, I recommend leaving stands in the mid-20s rather than tearing them up, though this depends on factors such as planting date and stand uniformity.

 

For a deeper dive into a real-world example from last spring, check out this video: Corn Stand Assessments and Replant Decisions.

 

Kneubuhler: You first must take a stand count. Measure 1/1,000 of a row and count live plants. For 30-inch corn, that’s 17 feet, 5 inches long. Repeat this process multiple times to get a respective average, and then consider additional factors like weak seed vigor along with potential yield loss. 

 

Other factors to consider are planting date, yield potential, replant costs, stage of corn plant development and herbicide implications to control weeds in the existing stand of corn. Planting date relative to the current date on the calendar tends to drive a lot of my decision-making. Ultimately, however, if final stands start to fall below 26,000 to 28,000, consider replanting. It takes ear count to achieve yield, and without plants, it’s difficult to gain an ear!

 

Quinn: The main factors to consider for a replant are the total stand loss across a field and the health and uniformity of the surviving plants. Walk areas of a field and take stand counts to assess total stand loss and health of surviving plants. This can also be combined with an overall field assessment from aerial imagery to understand the full extent of the damage and where the most troublesome areas are.

 

Assess plant health in areas with poor stands to identify the cause, which might be due to pests, disease, fertilizer burn or saturated soil. Determining why the stand is poor can help to determine ways to mitigate these issues in the future. Modern corn hybrids are tolerant to wider ranges in plant populations, meaning they can perform well at low and high plant populations. In many cases, significant yield losses may not be observed until the final plant population is below 23,000 plants per acre.

 

Lastly, consider the time of the year, availability and cost of replant seed, replanting costs, and corn grain prices to help dictate this decision.