Weeds steal water, nutrients and sunlight from crops, but now that the growing season is winding down, that’s a problem for next year, right?

Not so fast.

Weeds that survive, emerge or establish this fall can determine how difficult and expensive weed control becomes next spring.

For fields with a history of winter annual weeds, a fall burndown application can help growers start clean next spring while potentially reduce competition for moisture and nutrients, improve planting conditions and take one more job off an already crowded spring to-do list.

“Fall gives growers an opportunity to look across each field and address weed problems before they become bigger challenges next spring,” says Chris Mayo, HELM Crop Solutions technical sales agronomist located in the Heartland Region. “If winter annual weeds are already established, controlling them while they’re small can put you in a much better position when it’s time to plant.”

 

Chris-Mayo
Chris Mayo, technical sales agronomist, Heartland Region, HELM Crop Solutions

Timely burndown of these winter annual species can be difficult in spring, so growers with persistent problems should consider a fall burndown application, according to Iowa State University.

Fall weed management begins with post-harvest scouting. Henbit, chickweed, dandelion and horseweed, also known as marestail, are among the winter annual weeds that can establish in the fall and survive through winter, depending on your location.

Mayo suggests starting with known problem fields. Evaluate which weeds are present, their size and density, and whether crop residue could interfere with herbicide coverage. Those observations can help growers determine where a fall application makes sense and build an effective program.

The benefit of controlling winter annual weeds in the fall goes beyond a cleaner field. Dense weed growth can affect planting conditions the following spring.

University of Missouri  research found that winter annual weeds can affect soil temperature, remove moisture from the soil and take up nutrients that otherwise could be available to the developing crop. In research trials, soil moisture at planting was as much as 13% higher in corn and 6% higher in soybeans where winter annual weeds were removed with fall or early spring herbicide applications compared with areas with dense winter annual weed cover.

“Starting clean is about more than controlling what you see above ground,” Mayo says. When you eliminate a heavy mat of winter annuals, you can also reduce the moisture and nutrients those weeds use and create better conditions for planting and early crop establishment.

Fall burndown can also help growers manage another valuable resource: time.

Wet weather and narrow fieldwork windows can make timely spring burndown applications challenging. Moving some weed control to the fall can reduce the number of jobs competing for growers’ attention during the busy spring season.

For fields with persistent winter annual weed problems, fall applications also allow growers to target weeds while they are smaller, rather than waiting until they have overwintered and resumed growth.

“Spring weather doesn’t always cooperate, and growers have a long list of jobs competing for their attention,” Mayo says. “Taking care of winter annual weeds in the fall can remove one variable from the equation. You’re controlling weeds at a favorable stage and giving yourself more flexibility when the planter needs to roll.”

An effective fall burndown program should be based on the weeds present, field history, crop rotation and plans for the following crop. “Don't prescribe the same answer for every acre,” advises Mayo. “Understand the field, identify the problem, and use the right tool at the right time.”

Tools like Reviton®come to mind. It is a Group 14 PPO inhibitor featuring the active ingredient tiafenacil and controls or suppresses more than 50 broadleaf and grass weeds. It can provide flexibility in fall burndown programs and is an excellent tankmix partner for a comprehensive burndown program. With a low use rate, Reviton has demonstrated consistent burndown performance, including tough fall and winter weeds such as chickweed, dandelion, henbit and shepherd’s purse.

field_pennycress
Field pennycress is also among the winter annual weeds that are important to control in a fall burndown program. Reviton controls this weed.

Keep in mind that most fall programs should not be expected to control summer annual weeds into the following growing season. Weed experts specifically caution against counting a fall residual herbicide as an effective additional mode of action against summer-emerging weeds such as Palmer amaranth and waterhemp. Fall programs can, however, play an important role in managing troublesome weeds such as herbicide-resistant marestail.

“Every field is different, so start with the weeds that are actually there and build the program around them,” Mayo says. “Fall burndown is the first step in next year’s weed management program. Addressing those weeds now can reduce the pressure you carry into spring and help put the crop in a better position from day one. We’re in the eighth inning of this season, but there’s still plenty of time left to make a difference that will carry over into 2027 crop year.”

  • Weed control, fertility management and soil health work together to influence crop performance, herbicide efficacy and long-term profitability.
  • Resistance management requires a systems approach that includes crop rotation, diversified modes of action, residual herbicides and cultural practices.
  • Investments in soil health, pH management and multi-year planning help protect productivity, sustainability and return on investment for years to come.

Contact your local HELM representative  or agronomist to learn more about HELM's product portfolio and how it could work for you.

You can also take one or more of HELM's online learning modules.