Weeds

Wet springs have become the norm for farmers across the Midwest. The past couple of seasons have seen excessive rains, causing major flooding in some areas, delaying the start of planting and affecting field work producers need to do to prepare.

With so much moisture, Iowa State University Extension weed specialist Bob Hartzler said it’s even more critical to get any sort of weed protection on the ground.

“As much as anything, it’s the difficulty in getting applications made in a timely fashion,” he said. “When you go a couple weeks when there’s no days of being in a field, that just provides the weeds a huge advantage.”

Hartzler advised taking advantage of the windows of time with little to no rain to get a pre-emerge herbicide on the ground. That may mean before putting the seed in the ground.

“The pre-emergence products should be the foundation of our weed management programs,” he said. “We’ve gotten to the point where we focus totally on planting and getting the pre-emergence product down, but with the changing weather patterns, I don’t think pre-emergence products should be something we think about once we get the crop in the ground. We have to get it on in the time frame that maximizes their performance.”

Waterhemp and Palmer amaranth continue to be major issues for many farmers, Hartzler said. However, the flooding in parts of southwest Iowa and northeast Missouri last year allowed some cattails to get established. Hartzler said that shouldn’t cause farmers to overreact.

“Burn them down,” Hartzler said. “There will be some weeds that take advantage of these really flooded periods, but they don’t have the traits that allow them to survive under conditions that are favorable for crop production.”

Even if farmers have done a good job with weed control in the past, Bob Streit with Central Iowa Agronomics said it might be a different ball game for farmers who were flooded out this past year. He said anyone who farms downstream from a farmer with a major weed problem could see more issues this year as the seeds could have traveled with the floodwaters.

He said farmers in those situations should be prepared for just about anything.

“I was in a field southwest of Omaha back in 2018 and there were a bunch of Palmer amaranth that were probably 4- to 8-foot high,” Streit said. “They had big, long seed heads, and if each of those puts off 400,000 seeds per plant, a high percentage of them went downhill.”

Streit said the best way to take care of these problems is with a little tillage, and if that doesn’t cut it, hire someone to dig up the plants by the root.

DEKALB Asgrow technical agronomist Nicole Stecklein said despite the challenge of these travelling weeds, that’s no reason to change up a weed management strategy.

“Just be on the lookout for weed seeds that you’ve never had to deal with before,” Stecklein said. “Make sure that once you identify them, your weed management plan is still going to be effective against those.”