Take Action Against Resistant Weeds

No matter the weed challenge, environment or growing conditions, U.S. soybean and cotton farmers rely on the Roundup Ready® Xtend Crop System

Knowledge often equals power — especially when it comes to taming tough-to-control and resistant weeds. Devising a herbicide management plan is an easier task when you know what you’re combating.

If you farm soybeans or cotton, chances are that you are all too familiar with four of the nation’s most prolific weeds. But how well do you really know these enemies?


Giant ragweed

Giant ragweed is a competitive weed that is adapted to the fertile soil crop production acres of the Midwest and Eastern Corn Belt. It quickly grows above crops to compete for sunlight and create a dense canopy with its 4- to 8-inch-wide leaves.

Herbicide Recommendations

  1. Start weed-free at planting. Take full advantage of early-emerging populations by controlling all emerged weeds with tillage or an effective burndown.
  2. Suppress late-emerging weeds through the use of a residual herbicide, either in combination with a burndown or at planting in a tilled seedbed.
  3. Finish strong with multiple postemergence applications to control dense infestation of giant ragweed, especially in populations that exhibit extended emergence.


Kochia is competitive with crops and problematic in fallow periods between crops. Early-emerging kochia can reduce crop yields by 70% or more and can interfere with harvest.

Herbicide Recommendations

  1. Rotate crops to help diversify kochia-control strategies and herbicide programs over time.
  2. Start clean. It is imperative to control kochia in early spring because of its emergence patterns, dense populations and difficult-to-control large plants.
  3. Apply an effective soil-applied, pre-emergence herbicide.
  4. Target small weeds after they emerge.
  5. Prevent seed production. Strategic tillage and cover crops might be helpful in minimizing kochia seed production.

Marestail (Horseweed)

Horseweed competes with soybeans throughout the growing season and reduces crop yield. It matures in late summer or early fall and produces up to 200,000 seeds per plant, which are readily dispersed by wind.

Herbicide Recommendations

  1. Use fall or early spring herbicide treatments in fields where horseweed seedlings are observed.
  2. Apply effective burndown herbicides in spring. Do not plant into existing stands of horseweed. Start weed-free at planting.
  3. Include residual herbicides with the preplant-burndown treatment.
  4. In Roundup Ready 2 Xtend® soybeans, a postemergence application of XtendiMax® herbicide with VaporGrip® Technology, Roundup PowerMAX® herbicide and Warrant® Herbicide (with an approved DRA) will control horseweed plants that emerge after planting and also prevent a new flush of weeds from emerging later in the season.


Waterhemp is a prolific seed producer and able to produce as many as 1.5 times more seeds than most other pigweed species.

Herbicide Recommendations

  1. The most effective strategies to reduce herbicide-resistant waterhemp populations will integrate cultural and mechanical techniques with chemical control. Right before or after soybean planting, apply a full rate (according to label guidelines for soil type and organic matter content) of an effective pre-emergence, soil-residual herbicide.
  2. Apply an effective postemergence herbicide with an overlapping residual herbicide.
  3. Scout the field within seven to 14 days after the initial postemergence application to determine treatment effectiveness. If there are still surviving plants present, remove these plants from the field before they reach a productive growth stage.

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