Category Archives: Weed of the Month

Weed of the Month: Giant Ragweed

  • giant ragweedCommon name: Giant ragweed
  • Scientific name: Ambrosia trifida1
  • Grass or broadleaf: Annual broadleaf
  • Giant ragweed grows in the Midwest and Eastern regions of the United States, but it is most heavily concentrated in the eastern Corn Belt states like Indiana and Illinois.2
  • Germination timing: Giant ragweed is traditionally an early season weed; however, its growing season is expanding. Giant ragweed typically sprouts in early May but has been seen as early as March. The weed can continue to cause issues through late July and can impede harvest if not controlled.2
  • Competitiveness: Giant ragweed is one of the most competitive weeds in corn and soybeans.
    • Two giant ragweed plants within a 110 square feet area can reduce corn yield by 13 percent.2
    • Soybean yield can be reduced by 50 percent when there is just one giant ragweed plant within a 110 square foot area.2
  • Giant ragweed can grow 1-5 feet taller than competing plants and can reach heights of up to 17 feet tall.2

Fast facts

  • When a giant ragweed plant first emerges, it can be identified by its spatulate cotyledons. These cotyledons are spoon-shaped and can range from 1 to 1 ¾ inches long.2
  • Giant ragweed always has three distinct lobes but can show up to five lobes that grow in an opposite arrangement.2
  • According to WeedScience.org, the first confirmation of herbicide resistant giant ragweed in the United States was in an Indiana soybean field in 1998.
  • Giant ragweed is a monoecious plant, which means that separate male and female flowers can found on a single plant.2
  • Giant ragweed seeds can be identified by their points and ridges that make them look like small crowns.2

Weed management tips2

  • Use multiple modes of action:
    • One of the best ways to fight giant ragweed is to use multiple modes of action in a herbicide program with both preemergence and postemergence herbicides.
  • Scout for weeds:
    • Look for giant ragweed two weeks after the postemergence herbicide application and determine if another application is needed.

Resistance Statistics*

  • According to to WeedScience.org, herbicide-resistant giant ragweed has been documented in corn and soybean fields in 13 states: Arkansas, Illinois, Indiana, Iowa, Kansas, Kentucky, Minnesota, Mississippi, Missouri, Nebraska, Ohio, Tennessee and Wisconsin.*

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

Here are a few of the weed control solutions from Corteva Agriscience, Agriculture Division of DowDuPont:

Corn

DuPont Cinch® ATZ herbicide
Durango® DMA® herbicide
Elevore® herbicide
Enlist Duo® herbicide, as part of the Enlist weed control system
Enlist One herbicide, as part of the Enlist weed control system
Keystone® NXT herbicide
DuPont Realm® Q herbicide
Resicore® herbicide
SureStart® II herbicide
FulTime herbicide

Soybean

Durango® DMA® herbicide
Enlist Duo® herbicide, as part of the Enlist weed control system
Enlist One herbicide, as part of the Enlist weed control system
FirstRate® herbicide
Sonic® herbicide
DuPont Trivence® herbicide
DuPontEnlite® herbicide
DuPontAfforia® herbicide
DuPont™ FeXapan™ herbicide Plus VaporGrip® Technology

Additional information:

For more information, read these weed science resources:

Sources:
1University of Missouri Division of Plant Sciences 2018. Weed ID Guide, Giant Ragweed. https://weedid.missouri.edu/weedinfo.cfm?weed_id=18
2 University of Missouri 2014. Biology and Management of Giant Ragweed. https://weedscience.missouri.edu/publications/gwc-12.pdf

®™Trademark of The Dow Chemical Company (“Dow”) or E. I. du Pont de Nemours and Company (“DuPont”) or affiliated companies of Dow or DuPont. Cinch ATZ, FeXapan Plus VaporGrip Technology and Keystone NXT are federally Restricted Use Pesticides. Durango DMA, Elevore, EverpreX, FulTime NXT, Keystone NXT, Realm, Resicore, Sonic, SureStart II, Surveil and Trivence are not registered for sale or use in all states. FulTime NXT, Keystone LA NXT, Keystone NXT, Resicore and SureStart II 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. Enlist Duo and Enlist One herbicides are not registered for sale or use in all states or counties. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your area. Enlist Duo and Enlist One herbicides are the only 2,4-D products authorized for use in Enlist crops. DuPont™ FeXapan™ herbicide plus VaporGrip® Technology is a restricted-use pesticide. DuPont™ FeXapan™ herbicide plus VaporGrip® Technology is not registered for sale or use in all states. Contact your DuPont retailer or representative for details and availability in your state. IT IS A VIOLATION OF FEDERAL AND STATE LAW TO MAKE AN IN-CROP APPLICATION OF ANY DICAMBA HERBICIDE PRODUCT ON SOYBEANS WITH Roundup Ready 2 Xtend® technology, OR ANY OTHER PESTICIDE APPLICATION, UNLESS THE PRODUCT LABELING SPECIFICALLY AUTHORIZES THE USE. Contact the U.S. EPA and your state pesticide regulatory agency with any questions about the approval status of dicamba herbicide products for in-crop use with soybeans with Roundup Ready 2 Xtend® technology and follow all pesticide product labeling. Soybeans with Roundup Ready 2 Xtend® technology contain genes that confer tolerance to glyphosate and dicamba. Glyphosate herbicides will kill crops that are not tolerant to glyphosate. Dicamba will kill crops that are not tolerant to dicamba. Roundup Xtend® , VaporGrip® , Roundup Ready 2 Xtend® (Monsanto). VaporGrip® Technology is used under license from Monsanto Technology LLC. Always read and follow label directions. ©2018 Dow AgroSciences LLC

Weed of the Month: Palmer Amaranth

  • Palmer AmaranthCommon name: Palmer pigweed
  • Scientific name: Amaranthus palmeri 1
  • Grass or broadleaf: Annual broadleaf
  • Native to the Southwestern desert regions of the United States, Palmer amaranth has expanded rapidly across the Southeast and can be found in multiple Midwestern states.1
  • Germination timing: Palmer amaranth emergence is from early May until mid-September. This long emergence period forces farmers to manage the weed throughout the year, unlike other summer annual weeds that are typically managed only through early summer.1
  • Competitiveness: Known as the most competitive and aggressive pigweed species, Palmer amaranth can lead to soybean yield loss up to 79 percent and corn yield loss up to 91 percent in some states. It also can significantly increase production costs.2
  • Palmer amaranth grows fast – as much as 2 to 3 inches per day – and commonly reaches 6 to 8 feet.2
  • Farm equipment, specifically combines, and wildlife can spread Palmer amaranth seed into new, previously uninfected fields.1

Fast facts

  • Palmer amaranth has dioecious reproduction, meaning plants are either male or female, which forces outcrossing and genetic diversity.1 This makes it more difficult to control.
  • Each plant can produce 100,000 or more seeds when it competes with a crop. In noncompetitive scenarios, each plant can produce nearly a half million seeds.
  • According to WeedScience.org, the first confirmation of glyphosate-resistant Palmer amaranth in Midwest corn, cotton and soybean fields occurred in Missouri in 2008.
  • To identify Palmer amaranth, look for smooth green leaves arranged in an alternate pattern that grows symmetrically around the stem. The leaves are oval to diamond-shaped. There may be a small, sharp spine at the leaf tip.2
  • Palmer amaranth seeds are small and thrive in no-till or minimum-tillage fields.1

Weed management tips1

  • Rotate crops: this allows farmers to use herbicides with additional modes of action in the field.
  • Practice deep tillage: this will bury the small Palmer amaranth seed below its preferred emergence depth.
  • Plant a cereal rye cover crop: this crop can provide a mulch that will suppress Palmer amaranth emergence.
  • Harvest heavily infested fields last: because machinery so easily spreads Palmer amaranth seeds from one field to another, consider harvesting fields or parts of field with infestations last to limit seeds to that area.

Resistance Statistics*

  • According to WeedScience.org, herbicide-resistant Palmer amaranth has been documented in corn and soybean fields in 24 states: Alabama, Arkansas, California, Delaware, Florida, Georgia, Illinois, Kansas, Kentucky, Louisiana, Maryland, Michigan, Missouri, Nebraska, New Jersey, New Mexico, North Carolina, Ohio, Pennsylvania, South Carolina, Tennessee, Texas, Virginia and Wisconsin.

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

Corteva Agriscience, Agriculture Division of DowDuPont, offers the following weed control solutions:

Corn

DuPont Cinch® ATZ herbicide
Durango® DMA® herbicide
Elevore herbicide
Enlist Duo® herbicide, as part of the Enlist weed control system
Enlist One herbicide, as part of the Enlist weed control system
FulTime® NXT herbicide
Keystone® LA NXT herbicide
Keystone® NXT herbicide
DuPont Realm® Q herbicide
Resicore® herbicide
SureStart® II herbicide

Soybean

Durango® DMA® herbicide
Elevore herbicide
Enlist Duo® herbicide, as part of the Enlist weed control system
Enlist One herbicide, as part of the Enlist weed control system
DuPont EverpreX® herbicide
FirstRate® herbicide
Sonic® herbicide
Surveil® herbicide
DuPont Trivence® herbicide

Additional information:

For more information, read these weed science resources:

Sources:
1Purdue University Extension 2013. Palmer Amaranth Biology, Identification, and Management. https://www.extension.purdue.edu/extmedia/WS/WS-51-W.pdf
2Minnesota Department of Agriculture 2018. Palmer Amaranth in Minnesota. https://mda.state.mn.us/plants-insects/palmer-amaranth-minnesota

®™Trademark of The Dow Chemical Company (“Dow”) or E. I. du Pont de Nemours and Company (“DuPont”) or affiliated companies of Dow or DuPont. Cinch ATZ, FulTime NXT, Keystone LA NXT and Keystone NXT are federally Restricted Use Pesticides. Cinch ATZ, Durango DMA, Elevore, EverpreX, FulTime NXT, Keystone LA NXT, Keystone NXT, Realm, Resicore, Sonic, SureStart II, Surveil and Trivence are not registered for sale or use in all states. FulTime NXT, Keystone LA NXT, Keystone NXT, Resicore and SureStart II 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. Enlist Duo and Enlist One herbicides are not registered for sale or use in all states or counties. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your area. Enlist Duo and Enlist One herbicides are the only 2,4-D products authorized for use in Enlist crops. Always read and follow label directions. ©2018 Dow AgroSciences LLC

Weed of the Month: Waterhemp

  • waterhempVarious types: Common1
  • Scientific name: Amaranthus rudis1
  • Member of the pigweed (Amaranthaceae) family1
  • Grass or broadleaf: Broadleaf
  • Commonly found in Midwest states — native to North America1
  • Growing period: mid-May to early July3
  • Plants are male or female2

Fast facts:

  • Waterhemp can reduce yield by 74 percent in corn and 56 percent in soybeans if left unmanaged, according to Wisconsin Crop Weed Science, University of Wisconsin-Madison.1
  • Female plants produce 250,000 seeds per plant. However, one plant can produce up to 1 million seeds if there is little to no plant competition.2
  • Waterhemp can grow between 1 and 1.25 inches per day during the growing season, which is faster than most crops or weeds.2
  • Waterhemp seeds must be in the top inch of soil to successfully germinate and emerge.3
  • Waterhemp is a “multiple herbicide-resistant weed,” which means it cannot be controlled by at least two or more herbicides with different sites of action applied at labeled rates.4

Resistance Statistics:*

According to WeedScience.org:

As of June 2018, herbicide-resistant waterhemp has been reported in the following 18 states, listed in alphabetical order:

  • Arkansas, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, Oklahoma, South Dakota, Tennessee, Texas, Wisconsin

Managing waterhemp:

  • Tillage can help lower waterhemp populations because the seeds must germinate in the top part of the soil; however, tillage may not be a viable method of control on land prone to erosion.3
  • Narrower row spacing can help suppress waterhemp growth.3

Andy Asbury, field scientist, Corteva Agriscience, Agriculture Division of DowDuPont, Dow AgroSciences, offers advice:

  • Farmers should scout throughout the growing season to identify waterhemp early. This helps farmers plan timely herbicide applications and identify potential problem fields for the following year.
  • The best strategy to control waterhemp involves combining aggressive tillage and a program approach to herbicide application — including soil-applied herbicides followed by postemergence herbicide(s) with multiple, effective modes of action. Ideally, you would overlap preemergence residuals and postemergence residuals to reduce the number of germinating waterhemp plants.

Corteva Agriscience, Agriculture Division of DowDuPont, offers the following weed control solutions:

Corn

DuPont Cinch® ATZ herbicide
DuPont Realm® Q herbicide
Durango® DMA® herbicide
Elevore herbicide
Enlist Duo® herbicide, as part of the Enlist weed control system
Enlist One herbicide, as part of the Enlist weed control system
FulTime® NXT herbicide
Keystone® LA NXT herbicide
Keystone® NXT herbicide
Resicore® herbicide
SureStart® II herbicide

Soybean

Durango® DMA® herbicide
Elevore herbicide
Enlist Duo® herbicide, as part of the Enlist weed control system
Enlist One herbicide, as part of the Enlist weed control system
DuPont EverpreX® herbicide
DuPont Trivence® herbicide
FirstRate® herbicide
Sonic® herbicide
Surveil® herbicide

Additional information:

For more information, read these weed science resources:

  1. Butts, T. R., and V. M. Davis. 2014. Preliminary data suggests glyphosate resistance of two Wisconsin common waterhemp (Amaranthus rudis) populations. https://wcws.cals.wisc.edu/tag/amaranthus-rudis
  2. Bechman, T. J. 2017. 8 facts you should know about waterhemp in Indiana. http://www.indianaprairiefarmer.com/weeds/8-facts-you-should-know-about-waterhemp-indian
  3. Pioneer. Effective Management of Waterhemp. https://www.pioneer.com/home/site/us/agronomy/waterhemp-mgmt-soybean
  4. Ganie, Z., and J. Amit. Multiple Herbicide-Resistant Weeds and Challenges Ahead. https://cropwatch.unl.edu/multiple-herbicide-resistant-weeds-and-challenges-ahead

®™Trademarks of Dow AgroSciences, DuPont or Pioneer and their affiliated companies or respective owners. DuPont Cinch® ATZ, FulTime NXT, Keystone LA NXT and Keystone NXT are federally Restricted Use Pesticides. DuPont Cinch® ATZ herbicide, DuPont EverpreX herbicide, DuPont Realm® Q herbicide, DuPont Trivence® herbicide, Durango DMA, Elevore, FirstRate, FulTime NXT, Keystone LA NXT, Keystone NXT, Resicore, Sonic, SureStart II and Surveil are not registered for sale or use in all states. FulTime NXT, Keystone LA NXT, Keystone NXT, Resicore and SureStart II 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. Enlist Duo and Enlist One herbicides are not registered for sale or use in all states or counties. Contact your state pesticide agency to determine if a product is registered for sale or use in your area. Enlist Duo and Enlist One herbicides are the only 2,4-D products authorized for use in Enlist crops. Always read and follow label directions. ©2018 Corteva Agriscience

Weed of the month: Lambsquarters

  • lambsquartersVarious types: Common1
  • Scientific name: Chenopodium album1
  • Grass or broadleaf: Broadleaf
  • Found in all states
  • Germination timing: Summer annual. Lambsquarters emerges in the spring, sets seed in late summer/fall and dies.2
  • Competitiveness: Common lambsquarters is a highly competitive weed. Michigan State University reports 13 percent yield loss in corn with one lambsquarters plant per 1½ feet of row and 25 percent yield loss in soybeans with less than one plant per foot of row.2
  • Lambsquarters grows to 3½ feet in height and produces thousands of seeds.3

Fast Facts

  • Lambsquarters is a cool-season, early germinating annual broadleaf weed that can be most problematic in northern areas, says Jeff Ellis, field scientist, Corteva Agriscience, Agriculture Division of DowDuPont, Dow AgroSciences. Identify lambsquarters by looking for a white, “frosted” appearance of upper leaves.
  • According to WeedScience.org, the first confirmation of triazine-resistant lambsquarters in the United States occurred in Michigan in 1975. Today, lambsquarters is resistant to one or more sites of action in 22 states.
  • Cotyledons of common lambsquarters and redroot pigweed are similar; however, redroot pigweed cotyledons have a prominent midvein while lambsquarters cotyledons do not.3

Resistance statistics:*

  • Herbicide classes

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

Weed management tips:

Ellis says:

  • It’s important to scout for lambsquarters early because it tends to germinate early in the spring under cooler conditions.
  • Lambsquarters is difficult to control with glyphosate, especially when it grows larger than 3 or 4 inches.
  • The most effective lambsquarters control strategy requires a program approach with preemergence herbicides followed by early postemergence herbicide applications.

Corteva Agriscience, Agriculture Division of DowDuPont, weed control solutions:

Corn

DuPont Cinch® ATZ herbicide
DuPont Realm® Q herbicide
Durango® DMA® herbicide
Elevore herbicide
Enlist Duo® herbicide, as part of the Enlist weed control system
Enlist One herbicide, as part of the Enlist weed control system
FulTime® NXT herbicide
Keystone® LA NXT herbicide
Keystone® NXT herbicide
Resicore® herbicide
SureStart® II herbicide

Soybean

Durango® DMA® herbicide
Elevore herbicide
Enlist Duo® herbicide, as part of the Enlist weed control system
Enlist One herbicide, as part of the Enlist weed control system
DuPont EverpreX® herbicide
DuPont Trivence® herbicide
FirstRate® herbicide
Sonic® herbicide
Surveil® herbicide

Additional information:

For more information, read these weed science resources:

Sources:

1U.S. Department of Agriculture Natural Resources and Conservation Service. 2018. Plant Profile: Chenopodium album L. lambsquarters. http://plants.usda.gov/core/profile?symbol=chal7
2MSU Department of Plant, Soil and Microbial Sciences. 2018. Common Lambsquarters. https://www.canr.msu.edu/weeds/extension/common-lambsquarters
3University of Missouri Division of Plant Sciences. 2018. Common Lambsquarters. https://weedid.missouri.edu/weedinfo.cfm?weed_id=60

®™Trademark of The Dow Chemical Company (“Dow”) or E. I. du Pont de Nemours and Company (“DuPont”) or affiliated companies of Dow or DuPont. DuPont Cinch® ATZ, FulTime NXT, Keystone LA NXT and Keystone NXT are federally Restricted Use Pesticides. DuPont Cinch® ATZ herbicide, DuPont EverpreX herbicide, DuPont Realm® Q herbicide, DuPont Trivence®, Durango DMA, Elevore, FirstRate, FulTime NXT, Keystone LA NXT, Keystone NXT, Resicore, Sonic, SureStart II and Surveil are not registered for sale or use in all states. FulTime NXT, Keystone LA NXT, Keystone NXT, Resicore and SureStart II 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. Enlist Duo and Enlist One herbicides are not registered for sale or use in all states or counties. Contact your state pesticide agency to determine if a product is registered for sale or use in your area. Enlist Duo and Enlist One herbicides are the only 2,4-D products authorized for use in Enlist crops. Always read and follow label directions. ©2018 Dow AgroSciences LLC

Weed of the Month: Morningglories

  • MorninggloriesCommon name: Pitted morningglory, tall morningglory, ivyleaf morningglory
  • Scientific name: Ipomoea lacunosa, Ipomoea purpurea, Ipomoea hederacea
  • Grass or broadleaf: Summer annual broadleaf
  • Native to the United States, and widespread across the country
  • Except for the palm leaf morningglory, the first two morningglory leaves that emerge are butterfly-shaped.
  • Morningglory species can be identified by leaf shape, leaf hairs and flower color. Tall morningglory and ivyleaf morningglory produce purple or bluish-purple flowers, while pitted morningglory produces smaller, white flowers.
  • The weed produces large, hard seeds with an impermeable seed coat, making it tough to control.
  • Although there are no confirmed cases of herbicide resistance in morningglories, a tolerance to glyphosate has been documented.1

Fast Facts

  • A single tall morningglory plant per row foot can potentially cut soybean yield in half.1
  • Depending on the species, each morningglory plant can produce as many as 15,000 seeds.1
  • According to the Southern Weed Science Society, morningglories have been listed among the most common and most troublesome weeds for soybean growers in the organization’s weed surveys dating back to 1973.2

A fact that may surprise you …

  • Despite being considered a troublesome weed by farmers, morningglories are prized by gardeners for their colorful, trumpet-shaped flowers.

Morningglory control/management tips

Applying herbicides before planting and/or preemergence can provide good-to-excellent control of the morningglory species often found in crop fields. Postemergence herbicide applications are also recommended to control heavy infestations. In addition, planting in a narrow-row system to close the canopy more quickly can inhibit weed growth by decreasing sunlight available to the germinating morningglory plant. 

“In corn, morningglory often germinates after the crop reaches 12 inches tall,” says Andy Asbury, Enlist field specialist. “Atrazine, though effective, can’t be applied to corn after it reaches this height.”

Asbury notes growers can apply Enlist herbicides later in the growing season, up to the V8 growth stage or 30 inches, allowing control of more germinated morningglories.

“Morningglory in soybeans are often hidden by the crop canopy,” Asbury says. “The Enlist weed control system allows application of Enlist herbicides in soybeans through the R2 growth stage. The 2,4-D choline in both Enlist Duo and Enlist One herbicides is very effective in controlling vines such as morningglory.” 

Corteva Agriscience, Agriculture Division of DowDuPont, weed control solutions:

Corn

Resicore® herbicide
SureStart® II herbicide
Keystone® NXT herbicide
Keystone® LA NXT herbicide 

FulTime® NXT herbicide
Surpass® NXT herbicide 
Durango® DMA® herbicide
Enlist Duo® herbicide, as part of the Enlist weed control system
Enlist One™ herbicide, as part of the Enlist weed control system

Soybean
Sonic® herbicide
Surveil® herbicide
Durango® DMA® herbicide
Enlist Duo® herbicide, as part of the Enlist weed control system
Enlist One™ herbicide, as part of the Enlist weed control system


Additional information:

Identifying weeds in field crops, Michigan State University
Morningglory fact sheet, University of Missouri

Sources:
1United Soybean Board. 2016. Morningglory Management in Soybeans.
https://iwilltakeaction.com/uploads/files/54403-01-factsheet-morningglory-lr_1.pdf
2Hurst, H. R. 1991. Ivyleaf Morninglory Control in Soybeans with Serial Herbicide Applications.
http://mafes.msstate.edu/publications/bulletins/b0978.pdf

®™Trademark of The Dow Chemical Company (“Dow”) or E. I. du Pont de Nemours and Company (“DuPont”) or affiliated companies of Dow or DuPont. FulTime NXT, Keystone LA NXT and Keystone NXT are federally Restricted Use Pesticides. Duramax, Durango DMA, FulTime NXT, Keystone LA NXT, Keystone NXT, Resicore, Sonic, SureStart II, Surpass NXT and Surveil are not registered for sale or use in all states. FulTime NXT, Keystone LA NXT, Keystone NXT, Resicore, 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. Enlist Duo and Enlist One herbicides are not registered for sale or use in all states or counties. Contact your state pesticide agency to determine if a product is registered for sale or use in your area. Enlist Duo and Enlist One herbicides are the only 2,4-D products authorized for use in Enlist crops. Always read and follow label directions. ©2018 Dow AgroSciences LLC

Weed of the Month: Purple Deadnettle

  • Purple DeadnettleCommon name: Purple deadnettle
  • Scientific name: Lamium purpureum
  • Grass or broadleaf: Winter annual broadleaf
  • Native to Europe and Asia, and widespread across the United States
  • Purple deadnettle develops in the fall and forms a small rosette of leaves that can overwinter. It can easily be identified by its broad, egg-shaped leaves that are often red- or purple-tinged. This weed dons blue-to-purple flowers, living up to its name.
  • Completing its development in early spring, the plant forms flowers and then seeds. It dies in late spring to early summer, soon after seeding.
  • The weed resembles the henbit, a close cousin. The square stems of purple deadnettle and henbit are common characteristics for members of the mint family.
  • Commonly, this weed is present in areas where the soil has been disturbed, such as in fields, winter grain crops, gardens and orchards and along buildings.
  • Without any competition, the weed can spread rapidly, producing 27,000 seeds per plant. Sources report purple deadnettle seed can be viable after 660 years.1

Fast Facts

  • Purple deadnettle belongs to the mint family.
  • This weed thrives in nutrient-rich, sandy soils.
  • It can reach heights up to 18 inches.2
  • Although considered a weed, purple deadnettle is a food source to pollinators in early spring, providing pollen and nectar to several species of bees.

A fact that may surprise you …

  • In olden days, this plant family was commonly referred to as “archangels,” which is believed to refer to the clusters of hooded flowers appearing like a “choir of robed figures,” according to the University of Tennessee.2

Purple deadnettle control/management tips

Herbicides can provide good to excellent control of existing purple deadnettle and henbit. Fall and early spring treatments generally are more effective than postemergence treatment.1

A popular burndown treatment, the combination of glyphosate and 2,4-D, along with other residual herbicides, can provide broad-spectrum control of weeds including purple deadnettle. Atrazine also can be effective. If you use paraquat, control of purple deadnettle may improve by adding metribuzin.3

Cool conditions may slow activity of some burndown herbicides. Contact herbicides may work more quickly in cool temperatures. Consider the weather forecast, and assume weed reaction to be slower in colder conditions.

Dow AgroSciences weed control solutions:

Corn
SureStart® II herbicide
Resicore® herbicide
Keystone® NXT herbicide
Keystone® LA NXT herbicide 

FulTime® NXT herbicide
Surpass® NXT herbicide 
Durango® DMA® herbicide
Duramax® herbicide
Enlist Duo® herbicide, as part of the Enlist weed control system

Soybean
Sonic® herbicide
Surveil® herbicide
Durango® DMA® herbicide
Duramax® herbicide
Enlist Duo® herbicide, as part of the Enlist weed control system

Additional information:

More information can be found through these weed science resources:
Purple Deadnettle (Lamium purpureum L.), Michigan State University
Purple Deadnettle and Henbit, University of Tennessee

Sources:
1Michigan State University. 2017. Purple Deadnettle (Lamium purpureum L.)
http://www.msuweeds.com/worst-weeds/purple-deadnettle/
2Steckel, L. Purple Deadnettle and Henbit
https://extension.tennessee.edu/publications/Documents/W165.pdf
3Hager, A. 2011. Dealing With Henbit, Purple Deadnettle In No-Till Fields
https://www.no-tillfarmer.com/articles/1433-dealing-with-henbit-purple-deadnettle-in-no-till-fields

®™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, FulTime NXT, Keystone LA NXT, Keystone NXT, Resicore, Sonic, SureStart II, Surpass NXT and Surveil are not registered for sale or use in all states. FulTime NXT, Keystone LA NXT, Keystone NXT, Resicore, 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.  Enlist Duo herbicide is not registered for sale or use in all states or counties. Contact your state pesticide agency to determine if a product is registered for sale or use in your area. Enlist herbicides are the only 2,4-D products authorized for use in Enlist crops. Always read and follow label directions.

Weed of the month: Palmer amaranth

  • Palmer amaranthCommon name: Palmer pigweed
  • Scientific name: Amaranthus palmeri
  • Grass or broadleaf: Annual broadleaf
  • Commonly observed late spring through fall months and continues to emerge throughout the growing season — growing up to 3 inches per day in ideal conditions.
  • Known as the most competitive and aggressive pigweed species, Palmer amaranth can lead to corn yield loss up to 91 percent when allowed to compete with the crop throughout the growing season.1
  • Not only a threat to corn, season-long competition by Palmer amaranth at 2.5 plants per foot of row can reduce soybean yield by as much as 79 percent.1
  • Native to the Southwestern desert regions of the United States, devastation from Palmer amaranth has expanded across the Southeast and, recently, to the upper Midwest.
  • This invasive species has become one of the most significant weeds impacting cotton, corn and soybean production.

Fast facts from Jeff Ellis, Ph.D., field scientist, Dow AgroSciences

  • Palmer amaranth can adapt and quickly produce resistance genes to single-mode-of-action herbicides because individual plants are either male or female. This forces outcrossing and genetic diversity.
  • A single female plant can produce 600,000 seeds, which are rapidly spread through grain, seed, feed or equipment contamination.
  • Identifiable by its unique leaf shape, which is wide and ovate- to diamond-shape; Palmer amaranth leaves are commonly 2 to 8 inches long and a half-inch to 2½ inches wide.
  • Sometimes, the plants may show a white V-shaped watermark on the leaves. This watermark rules out other members of the pigweed family.

A fact that may surprise you …

  • Just how did an invasive desert plant make its way to the Midwest? Researchers believe Palmer amaranth was introduced to northern Indiana through manure from cattle that consumed seed-contaminated feed stocks from the South, such as cottonseed hulls. Farm equipment and wildlife also contribute to the spread of Palmer amaranth seed.

Resistance statistics*

  • According to WeedScience.org, herbicide-resistant Palmer amaranth has been documented in corn and soybean fields in 24 states: Alabama, Arkansas, California, Delaware, Florida, Georgia, Illinois, Kansas, Kentucky, Louisiana, Maryland, Michigan, Missouri, Nebraska, New Jersey, New Mexico, North Carolina, Ohio, Pennsylvania, South Carolina, Tennessee, Texas, Virginia and Wisconsin.

*Resistance confirmation does not necessarily include all weeds in a population are resistant. Levels of resistance may vary in different areas of each state.

Tips for controlling and managing Palmer amaranth:

  • The key to mitigating Palmer amaranth is making control a priority before the weed emerges and addressing it when the plant is small. Given the threat Palmer amaranth poses to yield, growers should implement a season-long management plan, using residual herbicides with multiple modes of action to prevent Palmer amaranth seeds from spreading.
  • Tank-mix residual herbicides with postemergence herbicides to help avoid emergence issues later in the season. Layering residual products is important to control this weed, which germinates throughout the growing season.
  • Soybean farmers, especially, should always use residual herbicides to help control Palmer amaranth after crop emergence because there are few effective postemergence herbicide control options.

Tips for managing herbicide-resistant weeds:

Farmers in the Midwest and Midsouth are no strangers to some of the toughest weed species, such as: Palmer amaranth, waterhemp, ragweed and marestail. Implement these management best practices to help manage weed resistance issues during the season.

  • Develop an integrated weed management plan that delivers multiple modes of action throughout the season. The Enlist weed control system allows use of effective postemergence modes of action, including new 2,4-D choline, glyphosate and glufosinate in soybeans and new 2,4-D choline and glyphosate in corn.
  • Use full rates of the herbicides during applications. Do not use partial rates for any reason, including cost.
  • Spray when weeds are small. Although application can be challenging because of weather and other factors, timing is critical to achieve the best control.
  • Scout fields regularly to identify weeds when they are small and easy to control.

Dow AgroSciences weed control solutions:

Corn
SureStart® II herbicide
Resicore® herbicide
Keystone® NXT herbicide
Keystone® LA NXT herbicide 

FulTime® NXT herbicide
Surpass® NXT herbicide 
Durango® DMA® herbicide
Duramax® herbicide
Enlist Duo® herbicide, as part of the Enlist weed control system
Enlist One herbicide, as part of the Enlist weed control system

Soybean
Sonic® herbicide
Surveil® herbicide
Durango® DMA® herbicide
Duramax® herbicide
Enlist Duo® herbicide, as part of the Enlist weed control system
Enlist One herbicide, as part of the Enlist weed control system

Additional information:

Find more information using these weed science resources:
Palmer Amaranth In Minnesota — Minnesota Department of Agriculture
Palmer Amaranth Biology, Identification and Management — Purdue University Extension
Guidelines for the Identification and Management of Palmer Amaranth in Illinois Agronomic Crops — University of Illinois Department of Crop Science
Palmer Amaranth Identified in Nine Iowa Counties — Iowa State University Extension and Outreach/Integrated Crop Management

Sources:

1 Minnesota Department of Agriculture. 2017. Palmer Amaranth In Minnesota.
https://www.mda.state.mn.us/plants/pestmanagement/weedcontrol/noxiouslist/palmeramaranth/palmeramaranthfs.aspx

®™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, FulTime NXT, Keystone LA NXT, Keystone NXT, Resicore, Sonic, SureStart II, Surpass NXT and Surveil are not registered for sale or use in all states. FulTime NXT, Keystone LA NXT, Keystone NXT, Resicore, 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. Enlist Duo and Enlist One herbicides are not registered for sale or use in all states or counties. Enlist Duo and Enlist One herbicides are the only 2,4-D products authorized for use in Enlist crops. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your area. Always read and follow label directions. ©2017 Dow AgroSciences LLC