Category Archives: Weed of the Month

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

Weed of the month: Burcucumber

burcucumber

Photo credit: Theodore Webster, USDA Agricultural Research Service, Bugwood.org

  • Common name: Burcucumber
  • Scientific name: Sicyos angulatus
  • Grass or broadleaf: summer annual broadleaf
  • Native to the United States
  • Resembles a cultivated cucumber
  • Burcucumber can be identified by its hairy, heart-shaped leaves and long vines.1
  • Burcucumber has separate male and female flowers (monoecious) that are white to pale yellow in color.2
  • Burcucumber develops forked tendrils, which can wrap around and climb up whatever the weed is able to reach, to attain sunlight.1 Vines can spread up to 25 feet and twine around corn plants. The weight of the vines can lodge corn, making it difficult to harvest.3
  • The fruit on the plant are typically produced in clusters of three to 20 and resemble cucumbers covered with bristles.4
  • The weed is typically found in low-lying areas near creeks and rivers, but it can be found on upland areas.

Fast facts

  • When burcucumber grows in direct competition of soybeans, it can reduce yield up to 48 percent.1
  • Burcucumber plants emerging in June can produce up to 42,000 seeds per plant.2
  • The hard seed coat the weed produces contributes to the prolonged seed dormancy, which means that fields infested with burcucumber will have a lasting seed reservoir in the soil and the potential for a burcucumber problem for many years.4
  • Burcucumber can germinate and emerge from soil depths up to 6 inches.4

Burcucumber control/management tips

David Hillger, Ph.D., Enlist field specialist, says:

  • To control burcucumber, follow a weed management program that includes residual herbicides and timely applications.
  • Farmers should look at their weed spectrum and select products that have the most effectiveness on their troublesome weeds. For burcucumber, if the selected postemergence product can be tank mixed with a residual product, farmers may want to consider this treatment for a final postemergence application.
  • At harvest, farmers should take care not to transport seed from an infested area to other parts of their fields or other locations. Farmers and retailers should initially bypass those areas in the field with the combine, return to them at the end of harvest and then follow with a thorough cleaning of the combine.
  • Use no-till in fields affected with burcucumber seeds. No-till allows burcucumber seeds to remain toward the surface, reducing the amount of time the seeds can germinate.

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:

Identification and Control of Burcucumber, University of Illinois
Why Residual Herbicides are Important Tools in Battling Hard-to-Control Weeds, University of Nebraska-Lincoln
Weed Management ― Burcucumber, Penn State Extension

Sources:

1 University of Missouri. 2014. Weed of the month: Burcucumber (Sicyos angulatus), An Agronomic Pest on the Increase.
https://ipm.missouri.edu/IPCM/2014/9/Burcucumber-An-Agronomic-Pest-on-the-Increase/
2 Purdue University. 2005. Identifying and Controlling Burcucumber.
https://www.btny.purdue.edu/WeedScience/2005/Burcucumber05.pdf
3 Purdue University Extension. 2011. Study to determine best management strategy for burcucumber in corn.
http://www.dairyherd.com/dairy-resources/forage/Study-to-determine-best-management-strategy-for-burcucumber-in-corn-117524034.html
4 Pennsylvania State University. 1997. Managing Burcucumber in Agronomic Crops.
http://extension.psu.edu/pests/weeds/control/managing-burcucumber-in-agronomic-crops/extension_publication_file

®™Trademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow. The Enlist weed control system is owned and developed by Dow AgroSciences LLC. FulTime NXT, Keystone LA NXT and Keystone NXT are federally Restricted Use Pesticides. 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. 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. Always read and follow label directions. ©2017 Dow AgroSciences LLC

Weed of the month: Waterhemp

  • waterhempCommon name: Tall waterhemp, common waterhemp
  • Scientific name: Amaranthus rudis
  • Grass or broadleaf: Annual broadleaf
  • Member of the pigweed family
  • Native to North America, specifically the Midwest, but can range from the western Southwest to East Coast.
  • Even though waterhemp flourishes in wet areas of land, it has become adaptable to other conditions.1
  • Seeds can germinate throughout the growing season and, if not controlled early, the plant can produce anywhere between 300,000 to 500,000 seeds per plant with a possibility of up to a million seeds. Proliferation can result in substantial yield loss.2
  • Plants emerge throughout the growing season, with some not germinating until later in the season. This can make it difficult for farmers to spray and control them as they may arise after first spraying has taken place. However, late-emerging plants produce smaller amounts of seeds that have low impact on yield.3

Waterhemp facts that may surprise you

  • Waterhemp is native to the United States and is now found in 40 states.
  • Waterhemp that grows later in the season is generally waxier, making it harder to kill.4

Fast facts

  • Waterhemp can only grow in shallow seed beds, making it a nightmare for no-till farmers.
  • Waterhemp is a dioecious plant, meaning it has separate male and female plants. This can be a disadvantage for waterhemp as it then must find the counterpart to become reproductive.5
  • Plants can range anywhere from 4 inches to 12 feet, but most are between 4 to 5 feet in agronomic settings.5
  • You can distinguish between the male and female plants by rubbing the mature flowers between your fingers. If you find tiny black seeds, the plant is a female.5
  • Waterhemp and weeds within the pigweed family can be hard to distinguish. Some ways to tell waterhemp apart is by its waxy/shiny appearance of leaves, hairless stem and leaf surfaces, egg-shaped cotyledons and alternate leaves.6
  • During its growing season, waterhemp has the ability to grow 1.5 inches per day.

Waterhemp control/management tips

According to Scott Ditmarsen, field scientist, Dow AgroSciences:

  • Waterhemp is a very prolific seeder and germinates throughout the growing season. It is a competitive weed due primarily to its sheer numbers and fast growth rate.
  • Farmers should implement timely and effective scouting throughout the growing season to identify waterhemp early. This helps farmers plan timely herbicide applications and identify potential problem fields for the following year.
  • Combining aggressive tillage and a program approach to weed control — including soil-applied herbicides followed by postemergence herbicide(s) with multiple, effective modes of action — is the best strategy to control waterhemp.
  • When feasible, physically remove escaped waterhemp plants to reduce competition and seed production.
  • Any cultural practices that improve crop competitiveness will improve the effectiveness of herbicide programs.

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

Soybeans
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:

Waterhemp has emerged; North Dakota State University
Are you ready for weeds?; University of Missouri
Management of ALS-resistant Palmer Amaranth and Waterhemp in the Panhandle; University of Nebraska

Sources:

1North Dakota State University. 2017. Waterhemp has Emerged in 2017. https://www.ag.ndsu.edu/cpr/weeds/waterhemp-has-emerged-in-2017-5-18-17

2University of Missouri Integrated Pest Management. 2015. Are you ready for weeds? https://ipm.missouri.edu/ipcm/2015/9/Are-you-ready-for-the-weeds/

3Lawrence, N. 2017. Management of ALS-Resistant Palmer Amaranth and Waterhemp in the Panhandle.
http://cropwatch.unl.edu/2017/management-als-resistant-palmer-amaranth-and-waterhemp-panhandle

4Gullickson, G. 2014. 22 Sobering Need-to-Know Facts About Herbicide-resistant Weeds. http://www.agriculture.com/crops/tech-tour/22-sobering-needtoknow-facts-about_196-ar42485

5Nordby, D., B. Hartzler, and K. Bradley. 2007. Biology and Management of Waterhemp.
https://www.extension.purdue.edu/extmedia/BP/GWC-13.pdf

6Werle, R., L. Sandell, and G. Kruger. 2013. Postemergence Control of Emerged Waterhemp in Soybeans.
http://cropwatch.unl.edu/postemergence-control-emerged-waterhemp-soybeans

 

®™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. Enlist Duo herbicide is 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. 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. Always read and follow label directions.  ©2017 Dow AgroSciences LLC

Weed of the month: Marestail

  • marestailCommon name: marestail, horseweed, Canadian fleabane, coltstail, butterweed
  • Scientific name: Conyza canadensis
  • Grass or broadleaf: Annual broadleaf
  • Native to North America (circa 1640), marestail is now found throughout the world.
  • A single female marestail plant can produce approximately 200,000 seeds that are transported by wind, providing for effective spread of herbicide-resistant populations.
  • Seeds germinate in the fall and overwinter in the rosette stage before emerging in two stages: late March and early June. Up to 90 percent of seeds that germinate in fall can survive through the winter.1
  • Mature plants grow erect, reaching heights from 6 to 10 feet tall. The main stem appears unbranched near maturity except for the flowering stems near the top. The central stem is covered with long white hairs; leaves alternate around the stem, appearing whorled.
  • Flowers bloom from June through September; yet unlike other winter annual broadleaf weeds, marestail does not mature until late summer, then it sets and disperses seed from August to October. Up to 86 percent of seeds produced can germinate right off the plant.2
  • Marestail is the first annual broadleaf weed documented to develop glyphosate resistance (14 states in 2000).3

Marestail facts that may surprise you

  • Native Americans used a tea steeped from marestail leaves to treat dysentery.
  • Marestail is a diuretic and can make humans sweat.
  • Marestail has also been referred to as fleabane because the leaves used to be put in pets’ beds to help to get rid of fleas.4

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

To correctly identify marestail when scouting, look for the following:

  • Scout for marestail year-round and learn to identify the weed in the small rosette stage.
  • First leaves have a broad, round end and whorled leaf arrangement that forms a rosette.
  • Marestail bolts in the spring. Leaves are alternate, hairy, 1 to 4 inches long, linear in shape and attached directly to stem.
  • Marestail is often misidentified as whitlowgrass, mouseear chickweed or several of the fleabane species, especially annual fleabane.
  • The larger the rosette is prior to winter, the greater the chance of survival into the spring. Spring marestail generally remains a rosette for a relatively short period prior to bolting.

Marestail control/management tips

Ellis says:

  • Timing is critical for marestail control
    • Farmers can find greater success at controlling marestail with more herbicide options when marestail is in the rosette stage of growth.
    • Controlling marestail after it has bolted is more difficult because there are fewer herbicide options.
  • Use glyphosate, 2,4-D, dicamba, ALS-inhibiting herbicides, and/or residual herbicides in fall and early spring burndown in no-till soybeans.
  • For in-crop soybeans, glyphosate tank-mixes with FirstRate® herbicide provide excellent control of bolted marestail. Pending registration, Elevore herbicide will be a new tool for farmers to use in burndown applications. Elevore will control marestail up to 8 inches tall.
  • Combining herbicides with good efficacy on marestail often provides the best control.
  • Use the full herbicide rates, recommended spray adjuvants and adequate spray volumes to optimize herbicide performance.

General tips to manage herbicide-resistant weeds

Take the following steps to manage herbicide resistance issues:

  • Develop an integrated weed management plan that delivers multiple modes of action throughout the season. With resistance increasing, the Enlist™ weed control system allows use of effective modes of action, including Enlist Duo® herbicide — new 2,4-D choline and glyphosate — and glufosinate in soybeans and Enlist Duo and FOPs in corn.
  • Using diverse herbicides or herbicide mixtures with different modes of action will reduce overreliance on any single herbicide and minimize the likelihood of selection pressure for resistance.
  • Use full rates of the herbicides during applications. Do not use partial rates or trim back for any reason, including cost.
  • Spray when weeds are small. Although it can be challenging because of weather and other factors, this is the ideal application timing.
  • 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

Soybeans
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:

Sources:

1Shaffer, G. 2016. Marestail Control. http://igrow.org/agronomy/soybeans/marestail-control/

2Michigan State University. Controlling Horseweed (marestail). http://fieldcrop.msu.edu/uploads/documents/Controlling%20Horseweed%20(Marestail).pdf

3Glyphosate, Weeds, and Crops Group, Purdue Extension Education. 2006. Biology and Management of Horseweed. https://www.extension.purdue.edu/extmedia/gwc/gwc-9-w.pdf

4Deane, G. Horseweed, Mare’s Tail. http://www.eattheweeds.com/conyza-canadensis-herb-fire-food-2/

®™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. Enlist Duo herbicide is 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. 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. Elevore is not yet registered with the U.S. EPA. This presentation is intended to provide technical information only and is not an offer for sale of product. Always read and follow label directions. ©2017 Dow AgroSciences LLC

Weed of the month: Giant ragweed

  • Giant ragweedCommon name: giant ragweed, great ragweed, horseweed, Texas great ragweed, buffalo weed, bitterweed, bloodweed
  • Scientific name: Ambrosia trifida
  • Giant ragweed is a native annual and is prevalent throughout the United States and much of Canada.
  • In soybeans, one giant ragweed plant can produce as many as 5,100 seeds per square yard. In corn, the number of seed produced per square yard can top 3,500.1
  • It emerges as temperatures warm in early spring, continuing to emerge into late July.
  • Because it emerges early in the season and grows very rapidly, giant ragweed competes with corn and soybeans for water, nutrients and light for the entire growing season.
  • Even relatively low populations of this competitive weed can cut soybean yield by 50 percent and can reduce corn yield by 13 percent.1
  • Research has shown the presence of stem-boring or stalk-boring insects in giant ragweed plants may reduce the effectiveness of glyphosate treatments as a control method.1

Fast facts from Jason Bond, Extension weed scientist, Mississippi State University, Dow AgroSciences

To correctly identify giant ragweed when scouting, look for the following plant-distinguishing features:

  • The seedling’s cotyledons are spoon-shaped and are relatively large, reaching up to 1⅝ inch in width and 1¾ inches in length.
  • Leaves generally have three distinct lobes but can have as many as five lobes.
  • Giant ragweed blooms from July to October in most areas of the country.
  • In corn and soybean fields, giant ragweed often grows anywhere from 1 foot to 5 feet taller than the competing crop. 1
  • Giant ragweed can reach up to 17 feet in height, creating a large, dense canopy that can quickly shade out area crops.

Resistance statistics*

  • Herbicide-resistant giant ragweed has been documented throughout much of the U.S. corn and soybean production area.
  • According to TakeActionOnWeeds.com, resistance to glyphosate (Group 9) has been confirmed in 11 Midwestern and Southern states.
  • Since the late 1990s, giant ragweed has shown resistance to ALS inhibitors (Group 2).
  • Resistance to both ALS-inhibitors (Group 2) and glyphosate (Group 9) has been documented in giant ragweed populations in several Midwestern states.

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

Giant ragweed control/management tips:

Bond says:

  • Start the crop year with a weed-free environment by applying a preplant burndown followed by a preemergence herbicide with residual activity to suppress later-emerging populations.
  • Use multiple postemergence herbicides with multiple modes of action, basing the number and frequency of applications on the size of the weeds and the population of giant ragweed present.

General tips to manage herbicide-resistant weeds

Growers in the Midwest and Midsouth face some of the most difficult-to-control weed species. Taking the following steps during the season can help manage weed resistance issues:

  • Develop an integrated weed management plan that delivers multiple modes of action throughout the season. With resistance increasing, the Enlist weed control system allows growers to use multiple postemergence modes of action, including glufosinate, glyphosate and a new 2,4-D in soybeans and FOPs, glyphosate and a new 2,4-D in corn.
  • Use full rates of herbicides during applications. Do not use partial rates or trim back for any reason, including cost.
  • Spray when weeds are small. Although it can be challenging because of weather and other factors, this is the ideal application timing.
  • 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

Soybeans
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 online at:  Management of Herbicide-Resistant Giant Ragweed — Take Action on Weeds

1Glyphosate, Weeds, and Crops Group, Purdue Extension Education. 2007. Biology and Management of Giant Ragweed. http://weedscience.missouri.edu/publications/gwc-12.pdf
2Take Action on Weeds. 2014. Management of Herbicide-Resistant Giant Ragweed. http://takeactiononweeds.com/wp-content/uploads/FactSheet_GiantRagweed.pdf

®™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. Enlist Duo is 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. Duramax, Durango DMA, Enlist Duo, 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. Always read and follow label directions. ©2017 Dow AgroSciences LLC

Weed of the month: Prickly sida

  • wom-prickly-sidaCommon name: Teaweed
  • Scientific name: Sida spinosa
  • Grass or broadleaf: Summer annual broadleaf
  • Native to the eastern two-thirds of the United States and prevalent across the South
  • One of the most troublesome weeds in peanuts, cotton and soybeans in the Southern states1
  • Emerges as temperatures warm in early spring, continuing through September, and can grow to 3 feet in height
  • Can produce approximately 1,000 seeds in a single weed
  • Can reduce yield potential by as much as 10 percent2

A fact that may surprise you

  • The common name of prickly sida is teaweed because the weed’s leaves look a lot like the leaves of a tea plant.

Fast facts from David Hillger, Enlist field specialist, Dow AgroSciences

To correctly identify prickly sida when scouting, look for the following plant-distinguishing features:

  • The seedling’s cotyledons are heart-shaped and covered with small hairs.
  • Leaves are small, ¾ to 2 inches long, oval-shaped with toothed margins and are alternately positioned on branched stems.
  • Prickly sida flowers are pale yellow with five petals.
  • Stems have small, blunt spines at the leaf and branch bases.
  • A member of the mallow family, prickly sida is related to velvetleaf and cotton.

Resistance statistics*

  • According to TakeActionOnWeeds.com, herbicide-resistant prickly sida has been documented in Georgia.
  • Since the early 1990s, prickly sida has shown resistance to ALS inhibitors (Group 2).

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

Prickly sida control/management tips:

Hillger says:

  • Plant soybeans early in narrow rows with high seeding rates.
  • Apply a preplant burndown followed by a soil-applied preemergence herbicide.
  • Use a postemergence herbicide treatment to control prickly sida before they get too large for adequate control.
  • Prickly sida experiences increased germination during high temperatures.

General tips to manage herbicide-resistant weeds

Growers in the Midwest and Midsouth face some of the most difficult-to-control weed species. Taking the following steps during the season can help manage weed resistance issues:

  • Develop an integrated weed management plan that delivers multiple modes of action throughout the season. With resistance increasing, the Enlist weed control system allows growers to use multiple postemergence modes of action, including glufosinate, glyphosate and a new 2,4-D in soybeans and FOPs, glyphosate and a new 2,4-D in corn.
  • Use full rates of herbicides during applications. Do not use partial rates or trim back for any reason, including cost.
  • Spray when weeds are small. Although it can be challenging because of weather and other factors, this is the ideal application timing.
  • 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

Soybeans
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 online at:
Prickly Sida (Teaweed) Management in Soybeans — United Soybean Board

1Virginia Tech Weed Identification Guide. 2016. Prickly Sida or Teaweed: Sida spinosa.
https://oak.ppws.vt.edu/~flessner/weedguide/sidsp.htm

2United Soybean Board. 2016. Prickly Sida (Teaweed) Management in Soybeans.
http://unitedsoybean.org/wp-content/uploads/54403_01-FactSheet_PricklySida_LR.pdf

®™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, 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. Always read and follow label directions. ©2016 Dow AgroSciences LLC

 

Weed of the Month: Palmer amaranth

  • Palmer amaranthCommon name: Palmer pigweed
  • Scientific name: Amaranthus palmeri
  • Grass or broadleaf: Annual broadleaf
  • Is native to the southwestern United States, has become a devastating weed problem in the South and has recently spread to the upper Midwest.
  • Most competitive and aggressive pigweed species. 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
  • Emerges later than many summer-annual broadleaf weeds, continues to emerge throughout the growing season and can grow 2 to 5 inches in three days or less.
  • A single female Palmer amaranth plant can produce approximately 600,000 seeds.
  • Ranked the most troublesome weed in the United States by the Weed Science Society of America (WSSA) for 2016.

A fact that may surprise you …

 The leaves, stems and seeds of Palmer amaranth are edible and highly nutritious; and the plants were once widely cultivated and eaten by Native Americans across North America, both for the abundant seeds and as a cooked or dried green vegetable.

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

To correctly identify Palmer amaranth when scouting, look for the following plant-distinguishing features:

  • The petioles, especially on older leaves, will be as long or longer than the leaf blade itself.
  • Plants sometimes — but not always — have a white V-shaped watermark on leaves. If a watermark is present, this rules out other members of the pigweed family.
  • Leaf shape on Palmer amaranth plants are wider than other pigweed species and ovate to diamond shape.
  • Individual plants are either male or female, which forces outcrossing and genetic diversity. This gives Palmer amaranth the ability to adapt and quickly produce resistance genes to single-mode-of-action herbicides.

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.
  • Since the late 1980s, Palmer amaranth has evolved resistance to six herbicide sites of action: ALS inhibitors (Group 2); microtubule inhibitors (Group 3); Photosystem II inhibitors (Group 5); EPSP synthase inhibitors (Group 9); HPPD inhibitors (Group 27); and, most recently documented in Arkansas and Mississippi, protoporphyrinogen oxidase (PPO) inhibitors (Group 14).

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

Palmer amaranth control/management tips:

Ellis says:

  • In both corn and soybeans, aim to control Palmer amaranth before plants emerge by using a residual herbicide.
  • Tank-mix residual herbicides with postemergence herbicides to prevent Palmer amaranth from emerging later in the season.
  • Palmer amaranth germinates throughout the season, so it is important to “layer” residual herbicides.
  • Growers, especially for soybeans, should always use residual herbicides and avoid having to control Palmer amaranth after emergence because there are very few effective postemergence herbicide control options.

General tips to manage herbicide-resistant weeds

Growers in the Midwest and Midsouth face some of the toughest weed species, including Palmer amaranth, waterhemp, ragweed and marestail. Taking the following steps during the season can help them manage weed resistance issues:

  • Develop an integrated weed management plan that delivers multiple modes of action throughout the season. With resistance increasing, the Enlist weed control system may allow use of effective postemergence modes of action, including glufosinate in soybeans and a new 2,4-D in corn and soybeans.
  • Use full rates of the herbicides during applications. Do not use partial rates or trim back for any reason, including cost.
  • Spray when weeds are small. Although it can be challenging because of weather and other factors, this is the ideal application timing.
  • 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

Soybeans
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:

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

1United Soybean Board. 2013. Palmer Amaranth Management in Soybeans. http://takeactiononweeds.com/wp-content/uploads/2014/01/palmer-amaranth-management-in-soybeans.pdf

®™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, 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. Always read and follow label directions. ©2016 Dow AgroSciences LLC