Perennial weeds are a challenge to control in-crop. Using a burndown in the fall is the best place to start for controlling weeds, but if the fall application was missed, then it’s time to make a plan for this spring. With spring burndown applications, you can ensure a clean start for the crop and manage resistant and perennial weeds like Canada Fleabane and dandelion. Timeliness is key for good knockdown and control of these weeds.
What is a burndown?
A burndown is a herbicide application to control emerged weeds. Burndown herbicide applications are important to remove early weed competition, control perennials and winter annuals and ensure control of glyphosate resistant weeds like Canada fleabane. It is an excellent opportunity to add some residual herbicide into your weed control program. Some burndown herbicides are systemic - they are absorbed into the plant and move to the growing points of roots, shoots or rhizomes and give longer-term control for perennial weeds. Some burndown herbicides are not systemic and target only above-ground green tissue. These contact herbicides control top growth, but do not give long-term control of perennials1.
Remember that weeds that emerge before or with the crop are the most competitive with the crop. Starting with a burndown removes these weeds and removes early weed competition.
When can I apply a burndown?
It depends on the weather. Uptake and translocation of systemic burndown herbicides can be slower following frosts or very cool nights. If nighttime temperatures are above 5°C, burndown applications can be made. It is important to check the weather forecast, and it’s better to apply a day or two after a cold weather event than right before one. Do not let the fields become overgrown with weeds before your application. The smaller the weeds are, the easier they are to control. The goal of the burndown is to keep the fields clean and prepare for successful planting.
What if my cropping plans change?
Always read and follow product label directions. There are more restrictions with residual herbicides. However, some products, like Elevore™ herbicide, allow flexibility like switching from field corn to soybeans. Other residual products may be more restrictive. It is a good idea to contact your Corteva Territory Manager to see what your options are.
What considerations should be included when planning your burndown herbicides?
Knowing what your weed spectrum is, what crop you have planned for the field, and even what herbicide tolerance that crop has are all important considerations. One of the benefits of early application is that you will have time to wait for the safe planting interval. Burndown herbicides may have cropping restrictions, so be sure to read and follow label directions. With an application of Elevore, there is a 7 day wait time before planting soybeans.
What burndown solutions are available from Corteva?
Elevore™ herbicide – Use Elevore for pre-plant burndown of broadleaf weeds, including glyphosate resistant Canada fleabane, in both field corn and soybeans. Elevore is highly systemic and very strong on fleabane. See how Elevore compares against the leading competitor on glyphosate resistant Canada fleabane in a 21 day study conducted by Dr. Francois Tardif of the Department of Plant Agriculture at the University of Guelph.
Conventional and herbicide tolerant soybeans are safe to plant 7 days after application of Elevore. We recommend using Elevore with a second mode of action like Canopy™ PRO herbicide, which provides metribuzin for fleabane control as well as residual activity for annuals. It is important to read and follow label directions, as there are specific surfactant requirements for this product.
Enlist Duo™ herbicide – Use ahead of any kind of field corn, but only registered for use in Enlist E3™ soybeans. Pair it with a product like Canopy PRO to ensure control of fleabane and provide residual control. For fields with waterhemp pressure, pair it with Diligent™ herbicide to get early season control of resistant biotypes. Waterhemp is hard to scout for and difficult to identify so, if it is a risk for your field, it is critical to have a residual herbicide that will control it in your burndown.