Category Archives: Weed & Disease of the Month

Weed of the Month: Kochia

kochiaKochia is a summer annual weed that is showing resistance to different herbicides in several states. The plant thrives in hot weather. So, a program approach featuring residual herbicides and several modes of action is key to controlling the weed throughout the growing season.

  • Common names: Kochia, Mexican fireweed, mirabel, mock cypress
  • Scientific name: Bassia scoparia
  • Cotyledons: Linear to narrowly lance-shaped
  • Leaf shape: Flat, linear to lance-shaped
  • Reproduction: Seed
  • Flowers: Clusters of green flowers with spiked heads

Fast facts

  • Kochia plants can resemble the shape of a Christmas tree.
  • The somewhat bushy weed can grow upward of 7 feet tall, with an extensive root system.
  • Young kochia plants may be confused with lambsquarters seedlings. Kochia has highly branched growth patterns with hairs occurring along leaf margins.
  • The weed germinates in the summer months, annually.
  • Kochia seed production is moderate to high. Seeds disperse via a “tumbleweed” mechanism, meaning a mature stem will detach from its base and then be blown about by wind.
  • Seeds are short-lived in the soil, but they possess a high initial germination rate.

Control tips

  • Corn and soybean growers should start spring with tillage or a burndown herbicide application. Experts advise applying the burndown shortly after the first flush of kochia has emerged.
    • Do not apply the burndown and preemergence herbicide in the same application. Kochia can grow larger and farmers may not achieve effective control.
  • With kochia showing resistance to ALS, glyphosate and triazine herbicides, it’s imperative to use a program approach to control the weed. Layer residual herbicides with multiple modes of action.
    • For example, to control kochia in a soybean field, you could apply Elevore® herbicide as a burndown, then Sonic® herbicide as a preemergent and DuPont EverpreX® herbicide as a postemergent.
  • Kochia thrives in hot weather, so it’s imperative to have residual control throughout the growing season.

States With Resistant Kochia by Crop*

States With Resistant Kochia by Crop

States With Kochia Resistant to Glyphosate*

States With Kochia Resistant to Glyphosate*

Corteva Agriscience offers the following weed control solutions:

Corn Herbicides

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 Herbicides
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
DuPontAfforia® herbicide
DuPontEnlite® herbicide
DuPont™ FeXapan® herbicide Plus VaporGrip® Technology
DuPont Trivence® herbicide


Source:
International Herbicide-Resistant Weed Database. 2020. Bassia scoparia. Kochia.
http://www.weedscience.org/Home.aspx

™®Afforia, Cinch, DMA, DuPont, Durango, Elevore, Enlist, Enlist Duo, Enlist One, Enlite, EverpreX, FeXapan, FirstRate, FulTime, Keystone, Realm, Resicore, Sonic, SureStart, Surveil and Trivence are trademarks of Dow AgroSciences, DuPont or Pioneer, and their affiliated companies or their respective owners. VaporGrip Technology is a registered trademark of Monsanto Technology LLC used under license. Cinch ATZ, FulTime NXT, Keystone LA NXT and Keystone NXT are Restricted Use Pesticides. FeXapan herbicide Plus VaporGrip Technology is a Restricted Use Pesticide. For retail sale to and use only by Certified Applicators and only for those uses covered by the Certified Applicator’s certification. Afforia, Cinch ATZ, Durango DMA, Elevore, Enlite, EverpreX, FeXapan herbicide Plus VaporGrip Technology, FulTime NXT, Keystone LA NXT, Realm Q, Resicore, Sonic, SureStart II, Surveil and Trivence are not registered for sale or use in all states. Keystone NXT is not available for sale, distribution 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 with Enlist crops. Consult Enlist herbicide labels for weed species controlled. Always read and follow label directions. © 2020 Corteva.

Disease of the Month: Northern Corn Leaf Blight

Northern Corn Leaf BlightThe disease of the month is northern corn leaf blight. Caused by the fungus Exserohilum turcicum, it’s an infection commonly found in corn. The disease is prevalent in the Midwest region of the United States and is more destructive when it gets a hold early in the growing season.

Symptoms — Elliptical, gray to tan lesions on leaves. Lesions can be anywhere from 1 to 6 inches long. Symptoms tend to start on lower leaves.
Geography — Midwest region of the United States, specifically Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota and Wisconsin.
Timing — June through September.
Conditions for development — Heavy dew, frequent rains, high humidity and moderate temperatures ranging from 65 F to 80 F.
Scouting tips — Plants are most susceptible post-pollination, but disease can take hold any time in development. Scout often and check lower leaves first.
Effect on yield — Early season infection can have a serious impact on yield, with losses up to 30%.
Management tips — Choose resistant corn varieties with your retailer, rotate crops, till fields to encourage decomposition of infected residue, and apply a fungicide preventively or, if necessary, curatively. DuPont Aproach® Prima fungicide is very effective at controlling stripe rust with preventive and curative modes of action. Visit AproachPrima.Corteva.us to learn use rates of the fungicide in corn.

Suggested Tweet to Your Customers: Learn how to control northern corn leaf blight at AproachPrima.Corteva.us.

™®Trademarks of Dow AgroSciences, DuPont or Pioneer, and their affiliated companies or their respective owners. Aproach Prima may not be registered for sale or use in all states. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. Contact your local Corteva Agriscience sales representative for details and availability. Always refer to the product labels for complete details and directions for use. © 2020 Corteva.

Weed of the Month: Waterhemp

waterhempThe battle against herbicide resistance continues as waterhemp persistently challenges growers and forces them to rethink their weed control programs. In the past 25 years, waterhemp has grown resistant to six classes of herbicides and threatens to resist various modes of action.

  • Common name: Tall waterhemp
  • Scientific name: Amaranthus tuberculatus1
  • Cotyldons: egg-shaped2
  • Leaf shape: long and narrow, smooth stems and leaves2
  • Reproduction: dioecious (separate male and female plants)2
  • Flowers: structure near top of plant and tips of branches2

Fast facts

  • History: Herbicide-resistant waterhemp was first discovered in 1993 in Iowa and it has spread across the Midwestern states within the past 20 years.3
  • Origin: Waterhemp is native to North America; however, waterhemp was not a weed found in crop fields like other pigweed species. Researchers believe waterhemp may have taken traits from a different Amaranthus species and moved from marshes to fields.1
  • Variations: There are two variations of waterhemp. One variation (Amaranthus tuberculatus var. rudis) is found west of the Mississippi River; the other variation (Amaranthus tuberculatus var. tuberculatus) is found east of the Mississippi.1
  • Fast-growing: Waterhemp grows quickly. A plant can grow 1-1¼ inches in one day.4
  • Many seeds: Waterhemp can produce about 250,000 seeds per plant and up to 1 million seeds without competition.4
  • Long-lasting seeds: Waterhemp seeds can germinate many years after they are produced. Some research shows that 12% of waterhemp seeds could germinate after four years.4

Control tips

  • Scout early — and often. Waterhemp looks very similar to Palmer amaranth early in its growth; however, there are differences. Look for longer, more lance-shaped leaves than pigweed species.5
  • Use multiple modes of action through various herbicide options. Layer residual herbicides to target different areas of the plant.5
  • Change row spacing. Narrower rows help crops get to canopy and overpower weeds before they grow too large to actively control.5
  • Use tillage, if appropriate. Waterhemp seeds cannot germinate unless they are in the top layer of soil. However, growers must be cautious of erosion.5
  • Utilize crop rotation. It can allow growers to change up herbicides and modes of action to help fight weed resistance.5

States with Herbicide-Resistant Waterhemp by Crop3

States with Waterhemp Resistant to Glyphosate3

Corteva Agriscience offers the following weed control solutions:

Corn Herbicides

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 Herbicides
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
DuPontAfforia® herbicide
DuPontEnlite® herbicide
DuPont™ FeXapan™ herbicide Plus VaporGrip® Technology
DuPont Trivence® herbicide


Sources:

1Iowa State University, Extension and Outreach. 2019. Waterhemp. a ‘friendly’ native evolves into the Cornbelt’s worst weed problem. https://crops.extension.iastate.edu/blog/bob-hartzler/waterhemp-friendly-native-evolves-cornbelts-worst-weed-problem
2University of Minnesota Extension. Annual broadleaf weeds. https://extension.umn.edu/weed-identification/annual-broadleaf-weeds#amaranth-family-id-waterhemp-palmer-amaranth-and-redroot-pigweed-838061
3International Survey of Herbicide Resistant Weeds. Herbicide resistant tall waterhemp globally. http://weedscience.org/Summary/Species.aspx
4United Soybean Board. 2018. Waterhemp management in soybeans. https://iwilltakeaction.com/uploads/files/54403-01-ta-factsheet-waterhemp-update-lr_1.pdf
5AGDAILY. 2018. Corteva Agriscience: five tips for fighting off waterhemp. https://www.agdaily.com/crops/corteva-agriscience-five-tips-waterhemp/

™®Afforia, Cinch, DMA, DuPont, Durango, Elevore, Enlist, Enlist Duo, Enlist One, Enlite, EverpreX, FeXapan, FirstRate, FulTime, Keystone, Realm, Resicore, Sonic, SureStart, Surveil and Trivence are trademarks of Dow AgroSciences, DuPont or Pioneer, and their affiliated companies or their respective owners. VaporGrip® is a registered trademark of and used under license from Monsanto Technology LLC. Cinch ATZ, FulTime NXT, Keystone LA NXT and Keystone NXT are Restricted Use Pesticides. FeXapan herbicide Plus VaporGrip Technology is a Restricted Use Pesticide. For retail sale to and use only by Certified Applicators and only for those uses covered by the Certified Applicator’s certification. Cinch ATZ, Durango DMA, Elevore, FeXapan herbicide Plus VaporGrip Technology, FulTime NXT, Keystone LA NXT, Realm Q, Resicore, Sonic, SureStart II and Surveil are not registered for sale or use in all states. Keystone NXT is not available for sale, distribution 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. EverpreX is not registered in all states. See your Corteva Agriscience retailer or representative for availability 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. Consult Enlist herbicide labels for weed species controlled. Always read and follow label directions. © 2020 Corteva.

Disease of the Month: Stripe Rust

The disease of the month is stripe rust, also known as yellow rust. Caused by a fungus called Puccinia striiformis, it is a disease commonly found in wheat. This disease can be found across much of the country, with appearances as early as January in Missouri and other states in the Midsouth.

stripe rust

Symptoms — Early symptoms include small, yellow flecks or spots appearing/arranged in linear rows (yellow streaks) on leaves. As the disease progresses, those flecks develop into elongated lesions/streaks (similar to stripes) of bright, yellow-orange spores.
Geography — Stripe rust can be found across the globe, including on wheat acres in the Midwest and Midsouth.
Timing — Late winter to midspring
Conditions for development — Cool, wet and humid weather. Temperatures between 45 to 54 F favor pathogen infection with peak disease development occurring between 50 and 65 F.
Scouting tips — Fungus spores can survive in wheat plants over winter and tend to clump during humid winter weather. Wind will spread those clumps relatively short distances to other plants. Look for early signs and scout often when weather conditions are right. You can also track when rust develops in states to the south to time when it could move into your area.
Effect on yield — It’s possible for stripe rust to cause 100% crop loss when there is cool, wet weather early in the season and disease progresses to the spikes.
Management tips — Choose seed treatments and resistant varieties. Good weed control can also help prevent disease. Apply a fungicide preventively and, if necessary, curatively. DuPont Aproach® Prima fungicide is very effective at controlling stripe rust with preventive and curative modes of action. Visit AproachPrima.Corteva.US to learn use rates of the fungicide in wheat.

Suggested Tweet: Learn how to control wheat stripe rust at https://www.corteva.us/products-and-solutions/crop-protection/aproach-prima.html.

™®Trademarks of Dow AgroSciences, DuPont or Pioneer, and their affiliated companies or their respective owners. Aproach Prima may not be registered for sale or use in all states. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. Contact your local Corteva Agriscience sales representative for details and availability. Always refer to the product labels for complete details and directions for use. © 2020 Corteva.

Weed of the Month: Velvetleaf

Originally from Asia and used as a fiber crop, velvetleaf was found in the United States around 1700. Today, velvetleaf can be found in fields as a weed and controlled by a variety of methods.

  • Common name: Velvetleaf
  • Scientific name: Abutilon theophrasti Medicus1
  • Annual or perennial: Summer annual1
  • Root system: Fibrous and taproot system2
  • Leaf arrangement: Alternate2
  • Leaf shape: Heart-shaped3
  • Flowers: Yellow with five petals3

Fast facts

  • Extreme heights: If left untouched, a velvetleaf plant can grow up to 7 feet tall.2
  • Seeds: Velvetleaf produces approximately 2,000 to 9,000 seeds per plant in capsules that contain 35 to 45 seeds.1
  • Competitiveness: If velvetleaf is left untouched, it can reduce corn yield by 20% to 34% if there are three plants per square foot.1
  • Soil Types: Velvetleaf thrives in compacted soils rich with nitrogen and with a high pH.1
  • Emergence: Velvetleaf emergences from the top 2 inches of soil. It will not survive germination if it remains on the soil surface.1

Identify differences between seedling velvetleaf, seedling prickly sida and seedling spurred anoda

  • Velvetleaf has one heart-shaped cotyledon and one round cotyledon; prickly sida has two heart-shaped cotyledons.2
  • Velvetleaf cotyledons are thicker than pricky sida cotyledons.2
  • Velvetleaf and spurred anoda both have similarly shaped cotyledons; but as the plant grows, spurred anoda’s first leaves are more triangular.2

Control tips

  • Flaming is an effective method for controlling velvetleaf.1
  • Hoeing can control velvetleaf if the plant is less than ¼ inch tall.1
  • A no-till situation can help control velvetleaf because the seed cannot survive on the surface.1
  • There are also herbicide options for velvetleaf control.1

Where Herbicide-resistant Velvetleaf Lives (according to WeedScience.org)

Corteva Agriscience offers the following weed control solutions:

Corn Herbicides

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 Herbicides
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
DuPontEnlite® herbicide
DuPontAfforia® herbicide
DuPont™ FeXapan™ herbicide Plus VaporGrip® Technology


Sources:

1Michigan State University, Department of Plant, Soil and Microbial Sciences. Velvetleaf. https://www.canr.msu.edu/weeds/extension/velvetleaf
2Steckel, L. Velvetleaf. https://extension.tennessee.edu/publications/Documents/W167.pdf
3University of Massachusetts Extension. Abutilon theophrasti. https://extension.umass.edu/landscape/weeds/abutilon-theophrasti

™®Afforia, Cinch, DMA, DuPont, Durango, Elevore, Enlist, Enlist Duo, Enlist One, Enlite, EverpreX, FeXapan, FirstRate, FulTime, Keystone, Realm, Resicore, Sonic, SureStart, Surveil and Trivence are trademarks of Dow AgroSciences, DuPont or Pioneer, and their affiliated companies or their respective owners. VaporGrip® is a registered trademark of the Bayer Group. Cinch ATZ, FeXapan herbicide Plus VaporGrip Technology, FulTime NXT, Keystone LA NXT and Keystone NXT are Restricted Use Pesticides. Cinch ATZ, Durango DMA, Elevore, FeXapan herbicide Plus VaporGrip Technology, FulTime NXT, Keystone LA NXT, Realm Q, Resicore, Sonic, SureStart II and Surveil are not registered for sale or use in all states. Keystone NXT is not available for sale, distribution 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. EverpreX is not registered in all states. See your Corteva Agriscience retailer or representative for availability 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. Consult Enlist herbicide labels for weed species controlled. Always read and follow label directions. © 2019 Corteva.

Weed of the Month: Purple Deadnettle

You may spy the color purple in the field and wonder what weed it is. While purple deadnettle looks similar to its relative henbit, they have various distinctive characteristics. Read below to learn how to identify and control purple deadnettle.

  • Common name: Purple deadnettle
  • Scientific name: Lamium purpureum1
  • Annual or perennial: winter annual2
  • Leaf arrangement: opposite2
  • Leaf venation: palmate2
  • Leaf width: ½ to 1 inch2
  • Leaf shape: triangular to heart-shaped3
  • Root type: fibrous2

Fast facts

  • Life cycle: Since purple deadnettle is a winter annual, it will grow best in the spring. It dies during the warmer summer months and will germinate again the fall. The weed remains dormant through the winter and grows well if warm weather is present.2
  • Reproduction: Purple deadnettle produces flowers in the spring that are blue and/or purple in color.2
  • Seeds: Approximately 27,000 seeds are produced per plant in areas without competition. The seeds then germinate in the early fall.1
  • Soil types: Purple deadnettle thrives in nutrient-rich soils. For example, you could find it in humic, loamy or sandy-loamy soils.1

Spot the differences between purple deadnettle and henbit

  • Purple deadnettle can reach heights of 16 to 18 inches tall; henbit can grow up to 15 inches tall.3
  • Both species have oval-shaped cotyledons; however, in henbit, the hypocotyl is green and turns purple as it grows.3
  • Henbit has hairs on the top of leaves, while purple deadnettle does not.3
  • The upper leaves of purple deadnettle are purple/red in color, while the lower leaves are a deep green. All leaves on henbit are green.3
  • Henbit has a square-shaped stem, while purple deadnettle does not.3

Control tips

  • Control is most effective in the fall, when the plants are germinating and young.1
  • Tillage is an easy way to control deadnettle when done in the spring.1
  • Many herbicides are effective when applied in the fall or early spring.1
  • If you are planting small grains, alfalfa or crops in a no-tillage system, deadnettle may compete for resources. Plant these crops at high rates to suppress its growth.1

Corteva Agriscience offers the following weed control solutions:

Corn Herbicides

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 Herbicides
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
DuPontEnlite® herbicide
DuPontAfforia® herbicide
DuPont™ FeXapan™ herbicide Plus VaporGrip® Technology


Sources:

1Michigan State University, Department of Plant, Soil and Microbial Sciences. Purple deadnettle. https://www.canr.msu.edu/weeds/extension/purple-dead­nettle
2Peacock, C. Purple Deadnettle. https://www.turffiles.ncsu.edu/weeds-in-turf/purple-deadnettle/
3Steckel, L. Purple Deadnettle and Henbit. https://extension.tennessee.edu/publications/Documents/W165.pdf

Additional Resource:

University of Missouri, Division of Plant Sciences. 2018. Purple Deadnettle. https://weedid.missouri.edu/weedinfo.cfm?weed_id=153

Afforia, Cinch, DMA, DuPont, Durango, Elevore, Enlist, Enlist Duo, Enlist One, Enlite, EverpreX, FeXapan, FirstRate, FulTime, Keystone, Realm, Resicore, Sonic, SureStart, Surveil and Trivence are trademarks of Dow AgroSciences, DuPont or Pioneer, and their affiliated companies or their respective owners. VaporGrip® is a registered trademark of the Bayer Group. Cinch ATZ, FeXapan herbicide Plus VaporGrip Technology, FulTime NXT, Keystone LA NXT and Keystone NXT are Restricted Use Pesticides. Cinch ATZ, Durango DMA, Elevore, FeXapan herbicide Plus VaporGrip Technology, FulTime NXT, Keystone LA NXT, Realm Q, Resicore, Sonic, SureStart II and Surveil are not registered for sale or use in all states. Keystone NXT is not available for sale, distribution 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. EverpreX is not registered in all states. See your Corteva Agriscience retailer or representative for availability 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. Consult Enlist herbicide labels for weed species controlled. Always read and follow label directions. © 2019 Corteva.

FeXapan® herbicide Plus VaporGrip® Technology is a Restricted Use Pesticide. For retail sale to and use only by Certified Applicators and only for those uses covered by the Certified Applicator’s certification. FeXapan herbicide Plus VaporGrip Technology is not registered for sale or use in all states. 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. VaporGrip Technology is a registered trademarks of Monsanto Technology LLC used under license.

Weed of the Month: Palmer Amaranth

Palmer amaranth of the pigweed group is becoming more invasive to the Midwest and causing agronomic issues. With its resistance to glyphosate and other ALS herbicides, this weed has an adaptable nature that continues to challenge farmers across the country.

Palmer Amaranth

  • Common name: Palmer Amaranth
  • Scientific name: Amaranthus palmeri1
  • Have a small hair in leaf tip notch1
  • Long petioles connect the leaf to the main stem1

Fast facts

  • Genetic diversity: Palmer amaranth is a dioecious species, which means that there are separate male and female plants. Dioecious species can increase genetic diversity, making it difficult to control.1
  • Many seeds: Each Palmer amaranth plant can produce at least 100,000 seeds in crop fields and up to a half-million seeds in undisturbed land.1
  • Undisturbed soil: Palmer amaranth thrives in no-till or minimum-till fields because it can emerge from the top few inches of soil.1
  • Extended emergence period: Palmer amaranth must be managed throughout the entire growing season due to its ability to emerge from early May to mid-September.1

Resistance statistics*

  • According to WeedScience.org, herbicide-resistant Palmer amaranth has been discovered in 28 states:* Alabama, Arizona, Arkansas, California, Delaware, Florida, Georgia, Illinois, Indiana, Kansas, Kentucky, Louisiana, Maryland, Michigan, Mississippi, Missouri, Nebraska, New Jersey, New Mexico, North Carolina, Ohio, Oklahoma, Pennsylvania, South Carolina, Tennessee, Texas, Virginia and Wisconsin.
  • Palmer amaranth has developed resistance against numerous herbicide modes of action, including the following: ALS inhibitors (Group 2), dinitroanilines (Group 3), triazines (Group 5), HPPD inhibitors (Group 27), PPO inhibitors (Group 14), long chain fatty acid inhibitors (Group 15), and glyphosate (Group 9).1

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

Identify the differences between common waterhemp and Palmer amaranth

  • Cotyledons of Palmer amaranth are long and narrow, while the cotyledons of waterhemp are not as elongated.2
  • True leaves (the leaves that follow cotyledon leaves) have a small notch, sometimes with a hair, in the tip.2
  • Early identification can allow for early herbicide usage to best control these weeds.2

Corteva Agriscience offers the following weed control solutions:

Corn Herbicides

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 Herbicides
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
DuPontEnlite® herbicide
DuPontAfforia® herbicide
DuPont™ FeXapan™ herbicide Plus VaporGrip® Technology


Sources:

1Legleiter, T., and B. Johnson. 2013. Palmer Amaranth Biology, Identification, and Management. https://www.extension.purdue.edu/extmedia/WS/WS-51-W.pdf
2Jhala, A., 2017. How to Differentiate Common Waterhemp and Palmer Amaranth Seedlings. https://cropwatch.unl.edu/2017/how-differentiate-common-waterhemp-and-palmer-amaranth-seedlings

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