The Growing Need for Fall Burndown

Posted on: Oct 27, 2022

In areas with high weed pressure, especially from winter annuals, the applications you make post-harvest can make a big difference in the spring. That’s why more and more producers are implementing fall burndown programs. As cropping techniques evolve, and planting dates are moved up, it’s a way to reduce the weed seed bank and stop hard-to-control species before they become a problem.

Winter annual species like marestail, henbit, chickweed and dandelion are more and more prevalent across the Corn Belt. Today, new hybrids and varieties are allowing farmers to plant earlier and harvest earlier. This creates an opportunity for these winter annuals to germinate, according to Keith Mach, an Agronomist with Helena Agri-Enterprises based in Lincoln, Nebraska. Removing the canopy from the field, he explains, can also lead to a late-season flush of summer annuals.

“You remove that canopy, the sun hits the weeds, and all of a sudden, they take off.” says Mach. “Those summer annuals will be small in stature, but they still produce seed, and we want to keep that seed bank empty as much as we can to help us with our program come spring.”

At this point in the fall, the goal is to get ahead of any late-season flush of weeds, keeping the field weed free before planting in order to support stand establishment and preserve soil fertility. Mach uses henbit to illustrate the challenge of playing catch-up in the spring.

“It’s there in the spring of the year with a pretty massive root structure pulling moisture and nutrients from that top two inches, and that's exactly where the corn seed or soybean seed is trying to emerge,” says Mach. “And now, it’s robbing everything there, so I’ve actually seen population reduced when planting through heavy weed patches of henbit and marestail.”

Even though these weeds die back later in the season, they create seed for the following season. This type of scenario is why Mach believes a fall burndown program is a best practice, using a combination of grass and broadleaf herbicides to cover a variety of different weeds with multiple modes of action. He stresses the importance of including a quality adjuvant in the tank when making applications in the fall to target winter annuals.

“Some of these weeds have a thick waxy cuticle, and we need an oil to break through that layer, and also because of the temperatures,” explains Mach. “Typically, they're a little bit cooler, and that activity on the leaf surface slows down as far as uptake and getting that active ingredient into the leaf.”

Mach recommends the combination of Latigo® Bold and Fire-Zone® because of its ability to control weeds with strength, speed and accuracy, even in cool temperatures. Latigo Bold contains dicamba and 2,4-D, optimized by Moveo® Formulation Technology to improve droplet deposition, rainfastness, leaf coverage and plant penetration. It is highly compatible with common burndown herbicides like glyphosate, and it has a low viscosity, reducing thickness and making it easier to handle in fall applications. Its activity is enhanced by a highly effective blend of MSOs (methylated seed oils) and surfactants in Fire-Zone.

“When you really want to get the biggest bang for the buck, you want to have an MSO,” says Mach. “Fire-Zone will help break through that cuticle, take that active ingredient, and get it into the plant sooner so it can move throughout, get to the action site, and kill the weed.”

Because every farm is different, weed control needs vary. Mach says the best way to start your fall burndown program is by having a conversation with your local Helena representative. For more information and other post-harvest tips, check out Episode 15 of the FieldLink podcast available on YouTube and these platforms: