As harvest gets underway in the Midwest, you and your customers may start to notice weed patches in their fields. Whether those are escapes from spring or newly emerging winter annuals, performing some fall soybean weed control measures could set your farmers up nicely for the 2022 season.
Corteva Agriscience field scientist Joe Armstrong recommends fall weed control for two big reasons.
“Fall soybean weed control is successful because the weeds are smaller and there are additional herbicide options available,” he explains. “By controlling weeds in the fall when they are small, growers will have less weed pressure to deal with in the spring, allowing them to start the year clean and begin planting earlier as soils warm up.”
Allowing weeds to overwinter can leave a farmer with a mess in spring. Controlling the weeds in fall can help keep seeds out of the weed seedbank. Armstrong says there are several species that fall control measures can (and should) target.
“Marestail is one of the main weeds that is often easier to control in the fall rather than the following spring,” he says. “Other winter weeds and perennials — such as henbit, field pennycress, annual bluegrass, Italian ryegrass and dandelion — can also be effectively controlled with fall burndown applications.”
“Marestail is one of the main weeds that is often easier to control in the fall rather than the following spring.”
Armstrong says fall weed control, despite the name, isn’t just about weeds. “Several winter annual weeds can also serve as alternate hosts for pests, such as soybean cyst nematodes,” he says. “By eliminating the weed hosts, these other pests can be more effectively managed.”
Armstrong’s No. 1 tip for fall soybean weed control is to make a burndown herbicide application, if timing allows, and he says Elevore® herbicide is a great choice for controlling difficult weeds like marestail. He says you’ll want to make sure the conditions are just right for an application.
“Fall burndown applications should be made after weeds have emerged and when they are actively growing, but before the weather gets cold and weeds harden off for the winter,” Armstrong explains.
If your customers are dealing with particularly thick or resistant weed patches, Armstrong recommends taking the burndown application a step further. “For dense weed populations or difficult-to-control weeds, a residual herbicide such as Surveil herbicide can further improve burndown activity and provide residual control into the following spring,” he says.
Armstrong says you could add other practices like tillage into the mix as well, but only if the soil isn’t too wet or frozen. “Fall tillage should only done when conditions are appropriate to avoid creating compaction,” he says.
“Fall burndown applications should be made after weeds have emerged and when they are actively growing, but before the weather gets cold and weeds harden off for the winter.”
If you’re in an area experiencing drought or dry weather this year, Armstrong says, your farmers may be able to pull back on their fall weed control a little bit. “Under drought or dry conditions, it is likely that there will be less weed germination and lower weed populations present in the fall. You’ll want to scout carefully to understand where the fields will benefit most from a fall application,” he says.
And while fall weed control can help lighten the load for farmers in spring, Armstrong warns they should still consider a spring burndown.
“A fall burndown will likely not eliminate the need for a spring burndown. However, it will reduce the overall weed density and size of any weeds present in the spring,” he explains. “Because you will have fewer and smaller weeds, this can help spread out the workload in the spring when burndown applications need to be made to prepare fields for planting.”
Armstrong says taking some steps now can help set your customers up for success in spring, because timely planting and clean fields ultimately lead to higher soybean yield potential.
The transgenic soybean event in Enlist E3® soybeans is jointly developed and owned by Corteva Agriscience LLC and MS Technologies, L.L.C. Elevore®and Surveil® are not registered for sale or use in all states. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. Consult the label before purchase or use for full details. Always read and follow label directions.