How much can volunteer corn affect corn yields?

June 5, 2012

By Bob Hartzler, Department of Agronomy

Many continuous corn fields across Iowa have significant volunteer corn problems this spring. 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.

As with any weed, the competitiveness of the volunteer corn is highly variable depending upon the specific situation. Research in South Dakota found that volunteer corn densities of 800 to 14,000 plants per acre caused yield losses of 0 to 13 percent.   Iowa State research found that 1,700 plants per acre (1 plant/10 feet of 30-inch row) caused 1.3 percent yield loss.  If dry conditions continue, the impact of volunteer corn on yields will increase. 

Volunteer corn can cause large yield losses.

Bob Hartzler is a professor of agronomy and extension weed specialist; contact him at or phone 515-294-1923.

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