Often referred to as the “weed seedbank,” the soil in corn and soybean fields can contain thousands of weed seeds per square foot. Deposits into the seedbank most often occur from mature weeds setting seed in the field, but weeds can also enter the seedbank by several other methods, including wind, water, animals and normal field operations.
“Weed seeds deposited into the soil can remain viable for years to come,” says Doug Jones, market development specialist, Corteva Agriscience.
On average, a weed seed can persist in soil and still be capable of germinating for up to five years. Tillage will increase that number, since weed seeds usually remain viable longer if they are buried.
“The best way to reduce the number of seeds in the weed seedbank is to prevent weeds from going to seed in the first place,” Jones says. “Fall burndown and residual herbicide programs can prevent fall-emerging weeds from establishing, which will provide a cleaner start next spring.”
There are several species that fall weed 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. A single marestail plant can produce up to 200,000 seeds, so it only takes a couple of seasons to take over a field.
Fall burndown applications can effectively control marestail and other winter weeds and perennials — such as henbit, field pennycress, annual bluegrass, Italian ryegrass and dandelion. This practice is not only useful for making withdrawals from the weed seedbank but also can reduce or eliminate the need for spring tillage.
But even with a fall burndown in place, keeping the weed seedbank under control is an ongoing job. Therefore, customers who wish to reduce their weed seedbanks will still want to implement a full program approach to weed control next year.
“When weeds first germinate, they are small and vulnerable to crop protection programs, but as the weeds get bigger, they require more aggressive management practices,” Jones warns. “Incorporating residual herbicides into a full program approach gives customers a better chance of success by managing fewer — and smaller — weeds.”
Whether your customers are looking for preplant, preemergence or postemergence options, herbicides for a one- or two-pass approach, or herbicides with longer residual activity, Corteva Agriscience can give your customers power over weeds (and their future seeds). Learn more about the corn herbicide solutions offered by Corteva here.