Weed Control Isn’t Just in a Jug

Chemical, Mechanical and Physical Weed Control is the Future

11/8/2021 | 8:28 AM CST

By  Matthew Wilde , Progressive Farmer Crops Editor

ANKENY, Iowa (DTN) — Mike Morgan has waged an all-out war on weeds for years in his Piggott, Arkansas, fields. He may be finally winning.

The main enemy is pigweed, particularly Palmer amaranth. The key to victory, Morgan said, is doing whatever it takes to conquer the weed seedbank and not settling for good-enough control. He’s found that a combination of effective herbicides with multiple modes of action and hiring chopping crews to remove weed escapees and burn them is effective.

But the war is far from over. “The fields are pretty clean now, but we’re still having weed trouble on field edges and seeing occasional escapes,” Morgan said.

Morgan knows herbicides alone no longer provide effective weed control. And in a year when many major herbicide active ingredients are in short supply or overly expensive, non-chemical solutions may be more important than ever.

Not long ago, Morgan was spending $100,000 or more annually on chopping crews that worked almost all summer to rid fields of Palmer amaranth because it threatened his livelihood. This year, he only spent about $10,000 to go after weeds manually because they weren’t as prevalent.

“If you don’t take care of pigweeds (Palmer amaranth), they will take care of you,” Morgan said. “You can see where they have totally taken over farms. We fight pigweed tooth and nail to keep the numbers down so they don’t explode.”

More than 250 weed species have developed resistance to herbicides, according to the Weed Science Society of America. If left unchecked, weeds may slice yields by depriving row crops of water, nutrients and sunlight.

Palmer amaranth and waterhemp, both members of the pigweed family, are particularly nasty and tough to control. Each is a prolific weed seed producer known to foil up to six and seven herbicide sites of action, respectively.

HOLISTIC APPROACH

Weed scientists urge farmers to adopt a holistic approach to weed control. This includes herbicides, hand weeding, cover crops, weed seed destruction, tillage and more.

Tom Barber, a University of Arkansas Extension weed scientist, said mechanical and cultural weed-control practices may not be cheap and easy, unlike when one pass of glyphosate did the trick. If farmers want to keep weeds at bay and preserve the efficacy of herbicides that still work, he said they need to consider multiple control methods.

“Farmers have to get out of the mentality that herbicides are the only answer,” Barber said. “Ever since glyphosate resistance became an issue, we made a huge shift in our education programs to focus on cultural practices to reduce weed numbers. Some farmers don’t want to do that because it costs more money, and it’s not as easy.”

COVER CROPS

Cover crops such as cereal rye and hairy vetch are Larry Steckel’s top nonchemical recommendations to fight herbicide-resistant weeds. Cover crops terminated just before or after planting can reduce Palmer amaranth infestations by 50%, according to the University of Tennessee weed specialist.