WEED OF THE MONTH: Common Ragweed

common-ragweedCommon ragweed is a highly competitive broadleaf weed that emerges early in the season and can threaten yield if left uncontrolled. Read the latest news on common ragweed and find helpful weed management information from Ryan Keller, Dow AgroSciences Enlist field specialist.

  • Various types: Annual ragweed1
  • Scientific name: Ambrosia artemisiifolia1
  • Grass or broadleaf: Broadleaf
  • Found in: AK, AL, AR, AZ, CA, CO, CT, DC, DE, FL, GA, HI, IA, ID, IL, IN, KS, KY, LA, MA, MD, ME, MI, MN, MO, MS, MT, NC, ND, NE, NH, NJ, NM, NV, NY, OH, OK, OR, PA, RI, SC, SD, TN, TX, UT, VA, VT, WA, WI, WV, WY1
  • Germination timing: Common ragweed germinates in early to mid-spring. When soil temperatures rise in late spring and early summer, common ragweed germination begins to taper off, according to Ryan Keller, Enlist field specialist, Dow AgroSciences.
  • Competitiveness:
    • Common ragweed is extremely competitive and impactful to yield when it emerges or germinates at the same time as the crop emerges. If it isn’t controlled before planting, common ragweed’s early germination allows it to interfere with crop growth at critical times in its development.
    • It tends to be more competitive in soybeans than in corn. Corn is a taller plant and shades weed competition. In addition, there are more effective herbicide options to control common ragweed in corn than soybeans.
    • When left to grow with the crop, common ragweed can significantly reduce yield.2 A 30 percent yield reduction in soybeans can occur from a common ragweed density of two plants per 10 feet.3

Fast facts:

  • Resistance to glyphosate and acetolactate synthase (ALS) herbicides is not the only herbicide efficacy problem of common ragweed. Stem boring insects hollow out the inner stem of this weed species. When that occurs, herbicides do not translocate properly to provide adequate control of the weed.2
  • The seed of common ragweed has very little to moderate dormancy in the soil. It takes less than one year for the seed bank to be reduced by 50 percent and about 10 years for 99 percent depletion.3
  • Common ragweed can grow as tall as 3 to 6 feet. Its hairy stems are green to light pinkish-red. The leaves are up to 6 inches long and 4 inches across. The leaves are compound, deeply cut into lobes and usually much wider at the base than the tip.2

Resistance statistics:

According to WeedScience.org:

*Resistance confirmation does not necessarily include all weeds and may vary among different areas of each state.

Weed management tips:

According to Keller:

  • Common ragweed typically emerges in undisturbed seedbeds like those found in no-till fields. Pay extra attention to fields that are managed with no-till or minimal tillage.
  • Scout areas of the field that tend to have standing water or are prone to leaching because common ragweed thrives in low-fertility environments.
  • Control common ragweed with residual preemergence herbicides that have multiple modes of action, such as SureStart® II herbicide in corn and Sonic® herbicide in soybeans. It’s important to use preemergence herbicides to control common ragweed before early season weed competition occurs.
  • Monitor fields seven to 10 days after herbicide applications to confirm common ragweed is controlled. If acceptable control hasn’t been obtained, rotate modes of action to a non-ALS or non-glyphosate application.

Dow AgroSciences weed control solutions:

Corn

SureStart® II herbicide
Keystone® NXT herbicide
Keystone® LA NXT herbicide
FulTime® NXT herbicide
Surpass® NXT herbicide
Durango® DMA® herbicide
Duramax® herbicide
Enlist Duo™ herbicide

Soybean

Sonic® herbicide
Surveil™ Co-pack herbicide
Durango® DMA® herbicide
Duramax® herbicide

Enlist Duo™ herbicide

Additional Information:

More information can be found through these weed science resources:

1 U.S. Department of Agriculture Natural Resources and Conservation Service. Plants Database. http://plants.usda.gov/core/profile?symbol=AMAR2
2Jordan, T., et al. Biology and Management of Common Ragweed. https://www.extension.purdue.edu/extmedia/bp/gwc-14.pdf
3Michigan State University. Common ragweed (Ambrosia artemisiifolia L.). http://www.msuweeds.com/worst-weeds/common-ragweed/

®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow. FulTime NXT, Keystone LA NXT and Keystone NXT are federally Restricted Use Pesticides. Duramax, Durango DMA, Enlist Duo, FulTime NXT, Keystone LA NXT, Keystone NXT, Sonic, SureStart II, Surpass NXT and Surveil Co-pack are not registered for sale or use in all states. FulTime NXT, Keystone LA NXT, Keystone NXT, SureStart II and Surpass NXT are not available for sale, distribution or use in Nassau and Suffolk counties in the state of New York. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. Always read and follow label directions. ©2015 Dow AgroSciences LLC