How Much Can Volunteer Corn Affect Yields?

Iowa fields have significant volunteer corn problems this spring. If dry conditions continue, farmers will need to plan ahead.

Published on: Jun 14, 2012

Many Iowa fields have significant volunteer corn problems this spring. If dry conditions continue, farmers will need to adjust combines to minimize harvest losses. Volunteer corn in a soybean field can be removed by spraying the right postemergence herbicide. But what do you do when you have volunteer corn in a corn-on-corn field?

"Many continuous cornfields across Iowa have significant volunteer corn problems this spring," says Bob Hartzler, Iowa State University Extension weed management specialist. "Unless this year's corn possesses a herbicide trait not present in the prior corn crop, there are no selective control practices available, other than cultivation. The lack of control options reinforces the value of adjusting combines to minimize harvest losses."

Figure 1. Volunteer corn can cause large yield losses.
Figure 1. Volunteer corn can cause large yield losses.

How much can volunteer corn in a cornfield affect corn yields?

That's a common question Hartzler is hearing from farmers this week. "As with any weed, the competitiveness of the volunteer corn is highly variable depending upon the specific situation," he says. He cites research in South Dakota found that volunteer corn densities of 800 to 14,000 plants per acre caused yield losses of 0% to 13%. Iowa State University research found that 1,700 plants per acre (1 plant/10 ft. of 30" row) caused 1.3% yield loss. "If the dry conditions that we are currently experiencing this spring in most of Iowa continue further into the month of June, the impact of volunteer corn on yields will increase," he says.