volunteer corn

The harvest delays in 2018 may have caused more yield loss than in previous years, making volunteer corn a bigger issue this year. 

With struggles during harvest in 2018, a lasting effect could come in the form of volunteer corn this growing season.

Brent Tharp, the agronomy and product training manager at Wyffels Hybrids, said wet weather and harvest delays last fall could mean more of the pesky problem.

“It all depends on harvest,” Tharp said. “I know we were challenged in a lot of fields, especially when the rains started. I think the later harvested fields, we could see more volunteers out there. The later harvest goes, the more natural harvest loss you get.”

Bob Hartzler, an Iowa State Extension weed specialist, said harvest loss is partially due to not taking the time to adjust combines properly, but part is due to factors farmers can’t control.

“With most weeds, how successfully you manage the weeds in the previous year has a big impact on your population,” Hartzler said. “With corn, it’s how much harvest loss you have. … A lot of farmers will have a bigger problem this year than in the past.”

Widespread volunteer corn can take away from overall field performance throughout the year if not handled properly. When it appears in a soybean field after a corn-soybean rotation, it can be easy to spot and manage, Hartzler said.

With most farmers using post-emergence herbicides, he noted that the issue may take care of itself. Some farmers may elect to add something extra to the treatments to attack the invading corn, but often, it comes down to determining if the extra cost is worth it.

When excessive volunteer corn is found in a corn-on-corn rotation, it can be tougher to deal with, Hartzler said.

“For corn, a lot of situations, they aren’t going to have a viable post-emergence option,” he said. “That’s why it’s so important for growers in continuous corn to make sure they take steps to minimize harvest losses.”

Volunteer corn can also bring increased risk for corn rootworm.

In a corn-soybean rotation, rootworm would generally die off in the soybean year. However, with volunteer corn, corn rootworm may find a place to sustain itself until the next year of corn rotation.

“If you have volunteer corn in your soybean fields and have rootworms, depending on the amount of volunteer corn, they can host rootworm larvae and carry them over to the next year,” Tharp said. “You are losing the effectiveness of your rotation.”

One of the most effective ways to limit volunteer corn is by using the cultivator and clearing out any lost kernels or ears from the previous harvest, Tharp said.

However, as different methods of soil management become more prominent, simply getting out the cultivator isn’t always an option, Hartzler said.

“Thirty years ago, most of the acres were cultivated, so that would take out a high percentage,” Hartzler said. “As we’ve gone to reduced tillage systems, that increases the recruitment of volunteer corn.”

Tharp said help managing volunteer corn now comes from other advancements in traits, such as stalk quality.

“It’s not a specific objective, but healthier corn stands longer and maintains its integrity longer into the season,” Tharp said.