Growers know the most difficult weed to control is the one that has emerged. Crop rotations and cover crops are key factors to successful weed management. Seasonal herbicide applications during critical crop growth stages can also help growers establish a well-rounded protocol for season-long weed eradication. In addition to a mixture of cultural practices, growers of all sizes can save time and labor when combining both preventative and prescriptive solutions to weed management.

Consider production strategies to control weeds

In no-till operations, traditional farming practices like conventional tillage are taken out of the management protocol. In that situation, growers can turn to other production methods to help control weeds. Consider these cultural strategies to help you successfully manage weeds:

Crop Rotation

Crop rotation can be effective in managing weeds, especially when applying multiple modes of action.

According to Ben Runge, a sustainable systems agronomy specialist with ForGround by Bayer, using the same herbicide repeatedly in a corn-on-corn rotation, for example, can lead to weed resistance.

“Crop rotation ensures that we are also rotating our herbicide modes of action,” Runge explains. He adds that when rotating crops, you should be aware that herbicides will need to be changed to best control weeds.

Cover Crops

Planting cover crops, especially going into winter, can help growers manage weeds, Runge says.

“Winter annuals really start emerging without pressure from other competing plant species,” he says. “Then, when we get into the active growing season, those cover crops can outcompete even further, hopefully shading weeds and keeping them from taking a good foothold in our fields.”

Runge says the more species you can include in a cover crop mix, the more effectively weeds can be controlled.

“Some species have specific advantages over others when it comes to competition and ground cover,” Runge notes. “Typically, a cereal rye blend is used, and that’s fine. Sometimes incorporating legumes and other species will help you get better ground cover.”

Intercropping

Along with cover crops, intercropping can help growers fill in spaces between rows that might call for more intensive weed management. With intercropping, the idea is to place more competition against weed species in those areas where focused attention is needed.

“It’s a great way in a no-till scenario to suppress and control weed species that are otherwise going to be very problematic within those rows,” Runge says.

Seeding Rates

Depending on the crop, the wider the row spacing, the more opportunity exists for weeds to compete. Increased space between plants allows more time for sunlight to reach the ground and weed species to grow.

Runge says managing seeding rates can be challenging because growers are navigating not only the competition between the crop and the weeds, but also the crop itself.

“(Seeding rates for) corn is mostly standardized but soybeans have quite a bit of deviation,” Runge says. “When we’re talking about seeding rates, we have to remember the thought process behind soybeans competing with each other.”

Safeguard crops with targeted management.

While you can get a jump start on weed control by implementing cultural production strategies, season-long management includes a prescriptive protocol. From herbicide selection and application to field scouting, growers can achieve a more balanced approach to weed management when combining these measures with field practices. Here’s how:

Timing is everything

One-pass herbicide applications add increased pressure for a chemical to control weeds throughout the growing season. According to Runge, a two-pass herbicide application can help growers step-up weed control throughout the growing season.

“A failure to plan is a plan to fail when it comes to herbicide timing,” Runge says. “We’ve really got to time herbicides correctly and ensure we’re applying the right rate at the right time and for the right species.”

Overlapping of residuals

Runge encourages growers to work with an agronomist to ensure their herbicide plans line up with future planting intentions. Doing so can help confirm the use of overlapping residuals in your weed management strategy. Still, Runge says to be aware of timing with overlapping residuals because some can inhibit cover crop emergence.

“It all goes back to timing,” Runge says. “Make sure you have a robust (weed management plan) that includes multiple modes of action, overlapping residuals and then select your herbicide with your agronomist for the weed species that you’re dealing with. There’s no one-size-fits-all plan for an entire operation.”

Applying multiple modes of action

The more modes of action in place, the better the chances of controlling a diverse weed spectrum within a field, Runge says. He gives this example.

A grower might think water hemp is what needs to be controlled in a field. It’s likely that a lot more weed species are present but not seen. Not only do multiple species need to be controlled, but also weeds that are resistant to certain modes of action and not to others.

“We’ve got to make sure we’re covering the full spectrum, both of weed species and of herbicide resistance,” Runge says.

Scouting of fields

It might seem obvious, but scouting fields plays a key role in successful season-long weed management. Runge says simply driving by a field can result in missing critical weed issues.

“We need to be out there looking constantly,” Runge says. “The more weed pressure we get or the bigger those weeds grow, the harder they are to control and the more opportunity you have for creating a weed seed bank that can eventually lead to more difficult problems.”

In addition to scouting fields, taking note of problem areas can help troubleshoot potential weed issues the next year. While a silver bullet doesn’t exist, combining preventative and prescriptive production strategies can help growers create a comprehensive, well-thought protocol for successful season-long weed management.

This article was written by Trust In Food in collaboration with Bayer