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Residual herbicides in Roundup Ready Systems offer value.

Agronomy Bulletin 12 ─ Evaluating Residual Herbicide

Did you know: If left unmanaged, a single common waterhelp can produce as many as 1 million seeds.


Growers can protect their investment in Roundup Ready® crops and maximize yield potential through the use of a residual herbicide, such as SureStart®II or Sonic®. SureStart delivers consistent, broad-spectrum weed control during early stages of corn growth and offers application flexibility. Sonic provides broad-spectrum foundation control of tough broadleaf weeds to reduce competition for emerging soybeans.

Factors to Consider

  • Difficult-to-control and resistant weeds
  • Noticeable increases in glyphosate rates
  • Use of reduced tillage
  • Multiple glyphosate applications in multiple crops
Did you know: At up to 16 feet tall, giant ragweed is one of the tallest summer annuals. It prefers moist soil and has distinctive three- to five-lobed rough leaves.

Action Plan

  1. Be aware of difficult-to-control and resistant weeds in your area. Many states throughout the Midwest and the South have experienced glyphosate-resistant weeds, reporting issues with marestail, ragweed, Palmer amaranth, and waterhemp, plus other hard-to-control weeds. SureStart II complements the performance of herbicide-tolerant traits by providing a sustainable way to manage hard-to-control weeds with additional modes of action.
  2. Watch out for increasing glyphosate rates. Even in areas where glyphosate resistance is not a confirmed problem, many growers are applying more glyphosate than in the past. University data shows a trend toward the use of higher glyphosate rates to achieve the same level of weed control previously achieved with lower rates.
  3. Plan weed control for reduced tillage or no-tillage. Reduced or no-till practices can cause multiple weed flushes and promote different weed species once controlled by tillage. In addition to reducing yield, annual weeds play host to cutworms in corn and cyst nematode in soybeans. Residual herbicides with multiple modes of action should be an essential part of a weed control program in reduced-till or no-till.
  4. Multiple glyphosate applications in multiple crops. With the advent of more glyphosate-tolerant crops, many growers are relying solely on the single mode of action of glyphosate to control weeds on more of their acres year after year, increasing the chances for weeds to develop resistance. SureStart II, for example, contains three modes of action, offering the broadest spectrum of control against 60 tough grasses and broadleaves. Sonic offers two unique modes of action to control tough broadleaf weeds.


Residual herbicides play an important role in extending the longevity of the glyphosate-tolerant cropping system. With multiple modes of action, they help reduce the chance of weeds becoming increasingly difficult to control or developing resistance. They also help to keep glyphosate rates in line with label recommendations and provide effective weed control in reduced tillage systems. Utilizing residual herbicides defends against weeds while extending the longevity of glyphosate as a viable option for weed control. For more information, contact your local Mycogen Seeds commecial agronomist or trusted agronomic adviser.

Published on Friday, January 16, 2015