Agronomy Talk

Agronomy Talk: Spring Burndown

Published on Wednesday, April 03, 2019

CLICK HERE FOR A DOWNLOADABLE VERSION OF THIS AGRONOMY TALK UPDATE

Weed competition at planting can reduce yields. As temperatures start to increase, weeds will flourish, and you will be faced with a short timeline to complete field operations. While it may be tempting to begin planting as soon as possible, it is important to make sure weeds are managed prior to planting. Attempting to control weeds after planting can interfere with your planting operations and create competition with the emerging crop for sunlight, moisture, and nutrients, reducing yields. As weeds continue to grow, they become more difficult to control.


ABOVE: Soybean yield due to delayed burndown herbicide applications. Burndown applications were made seven days prior to planting at unifoliate to V1 (1-trifoliate) soybean and V3 (3-trifoliate) soybean. Source: Michigan State University Extension.

Spring Burndown Best Management Practices:
A successful burndown treatment will help manage and reduce the soil weed seed bank while reducing the likelihood for development of herbicide-resistant weeds; however, it is imperative to achieve complete mortality because weeds that have been injured by a failed burndown are harder to control later.

Tips for a Successful Burndown:

  • Carrier Volume: Contact herbicides such as Gramoxone® require a much higher carrier volume than systemic herbicides such as Roundup PowerMax®. This is especially important when facing dense weed pressure.
  • Water Conditioning and Adjuvants: Hard water requires conditioning of the carrier water with AMS or an AMS product before the herbicide is added to the spray solution. Some products, such as Sharpen®, require the use of methylated seed oil (MSO) for adequate cuticle penetration. Ensuring that a lethal dose of herbicide gets into the plant is essential. It’s important to read the herbicide label and follow the manufacturer’s recommendation of adjuvants, surfactants, and mixing order.
  • Application Timing: The time of day in which you apply your burndown can have a significant impact on its efficacy. Be sure to read and follow any plant back intervals before planting your cash crop.
  • Rate vs. Height: Most herbicide labels have a recommended dosage to control a specific weed at a specific height. This is especially important as weeds become larger and denser, interfering with smaller weeds receiving a lethal dose.

For a list of plant back restrictions, see page 36-37 of Beck’s Recommended Herbicide Programs for Soybeans Brochure at bit.ly/HerbicideBrochure2019.

Spring Burndown Along with Effective Residual Herbicides

Start clean and remain clean. Season-long weed control is the result of an effective burndown treatment and the use of residual herbicides. Utilizing residual herbicides or herbicide pre-mixes with multiple sites of action (SOAs) is the most effective means of achieving successful, long-term weed control. The most effective residual herbicide program should target known problematic weed species while also managing herbicide-resistant weed populations. If planting is delayed following an initial burndown application, a second burndown treatment may be necessary before planting to ensure a clean field at emergence.

For assistance in creating a complete soybean herbicide program specific to your weed spectrum, please refer to the Beck’s Recommended Herbicide Programs for Soybeans brochure. Please remember to always read and follow label directions.


Source: Weed Response to Burndown Herbicides. Ohio, Indiana, & Illinois Weed Control Guide. Page 27. 2017

 

CLICK HERE FOR A DOWNLOADABLE VERSION OF THIS AGRONOMY TALK UPDATE

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