Weeds: The Fearsome Five

Although there are currently dozens of weeds that show some kind of resistance to herbicides, these five are the most troublesome.

Palmer amaranthPALMER AMARANTH | Amaranthus palmeri
• One of 865 members of the pigweed family. Grows faster and is more competitive than any other of the pigweed family.
• Has male and female plants, allowing for greater genetic variability and adaptability.
• Each plant can produce up to 1 million seeds.

WaterhempCOMMON/TALL WATERHEMP | Common Waterhemp (Maranthus rudis); Tall Waterhemp (Amaranthus tuberculatus)
• Members of the pigweed family.
• Tall waterhemp has smooth, erect stem that can grow more than 8 feet tall. Male and female flowers found on separate plants.
• Germinates over relatively long time period and grows rapidly.
• Waxy, narrow leaves slows herbicide uptake.
• Prolific seed producer (more than 250,000 seeds per plant). Seed can be dispersed over long distances, also is readily transported when equipment is moved from field to field.

MarestailHORSEWEED/MARESTAIL | Conyza canadensis
• One of the most common weeds in eastern and central parts of U.S.
• Well-adapted to no till-crop production; can quickly spread to many habitats along field edges and roadsides.
• Produces up to 200,000 tiny seeds per plant that are wind-dispersed over great distances. Up to 80% of seeds can germinate immediately
after dispersal.

Giant RagweedGIANT RAGWEED | Ambrosia trifida
• One of largest annuals, averages 5 feet in height, but can grow as large as 10 feet.
• Can produce over 11,000 seeds per plant without competition.
• In Midwest, can reduce corn yield up to 37%, soybean yield up to 52%.

Common LambsquartersCOMMON LAMBSQUARTERS | Chenopodium album
• Grows to more than 5 feet tall.
• Can produce 150,000 seeds per plant. Seeds can germinate in soil for a number of seasons.
• Highly competitive to plants. Just over 75 lambsquarters per square yard can reduce soybean yield by 50%.
• Difficult to control with postemergence herbicides. Wax on leaf surface slows herbicide movement into leaf and can affect subsequent control.

Topics:

Leave a Reply

Weed Resistance Stories
Weed ResistanceWeeds: The Fearsome Five
October 1, 2013
Although there are currently dozens of weeds that show some kind of resistance to herbicides, these five are the most troublesome. Read More
Weed ResistanceWeed Management Program Profiles
October 1, 2013
Here’s quick look at weed control strategies and their cost. Read More
Weed ResistanceRecognizing Resistance
October 1, 2013
Recognizing the presence of herbicide-resistant weeds and formulating a total management plan is becoming more important than ever. Read More
Mature Waterhemp in Corn
Weed ResistanceWhen Weed Control Goes Wrong
October 1, 2013
Beyond the possibility of resistance developing, ineffective control exacts cost to growers in lost yield. Read More
Top 100 Articles
CropLife 100The Andersons Acquires South Dakota Plant Nutrient Manufacturer Kay-Flo
May 20, 2015
The Andersons, Inc., ranked No. 22 on the CropLife 100, has purchased Kay Flo Industries of North Sioux City, SD. “This Read More
CropLife 100North Central Farmers Elevator, Wheat Growers Unification Approved By Board, Still Awaits Member Approval
May 13, 2015
The Boards of Directors for North Central Farmers Elevator (NCFE) and Wheat Growers (WG) have voted to approve the Unification Read More
CropLife 100AgGateway’s Barcoding Initiative Progressing Nicely
May 8, 2015
According to legend (or Wikipedia), the first step towards modern bar codes came back in 1948, when Bernard Silver, a Read More
CropLife 100Pinnacle Agriculture Acquires Minnesota Retailer
April 14, 2015
Pinnacle Agriculture Holdings, LLC, ranked No. 6 on the CropLife 100,  has successfully acquired Liebl Ag, LLC in Ada, MN.  Read More
CropLife 100CHS, Aurora Cooperative Complete Fertilizer Storage, Grain Shuttle Loading Facility
April 13, 2015
CHS Inc., the nation’s leading cooperative and ranked No. 5 on the CropLife 100, and Aurora Cooperative (ranked No. 21) Read More
CropLife 100GROWMARK Acquires Missouri Refined Fuels Terminal
April 2, 2015
Bloomington, IL-based GROWMARK and Magellan Pipeline Co. have entered into an agreement in which GROWMARK will acquire the refined fuels Read More
Latest News
ManagementA New Sprayer Company & UAV Research In The Spotlig…
May 21, 2015
CropLife’s Paul Schrimpf and Eric Sfiligoj talk about a Dutch sprayer manufacturer entering the U.S. with a super-sized entry and Read More
HerbicidesFirst U.S. Sale Of Enlist Duo Herbicide Made By Dow Agr…
May 21, 2015
Dow AgroSciences has recorded the first U.S. sale of Enlist Duo herbicide with Colex-D Technology. This marks the first commercial Read More
CropLife 100The Andersons Acquires South Dakota Plant Nutrient Manu…
May 20, 2015
The Andersons, Inc., ranked No. 22 on the CropLife 100, has purchased Kay Flo Industries of North Sioux City, SD. “This Read More
EquipmentNORAC Options Coming To TerraGator
May 19, 2015
Utilizing NORAC’s Standard Control technology, boom height control is now available for TerraGators with Airmax Precision 2 and Benson Booms. This Read More
Crop InputsHelena Introduces New Soil Health Product
May 19, 2015
Helena Chemical Co. is helping agricultural producers maximize yields and efficiency with the introduction of Liquid Chisel, a new product Read More
Stewardship4R Nutrient Management Planning Certification Now Avail…
May 19, 2015
The American Society of Agronomy (ASA) and the International Certified Crop Adviser (ICCA) program announce a new specialty certification in Read More
Environmental Defense Fund logo
Paul SchrimpfEnvironmental Defense Fund: Appreciating Partners
May 19, 2015
I WAS deep in the throes of preparation for the Commodity Classic meeting that took place this past February, trying Read More
WebinarsUpcoming Webinars
May 19, 2015
Register for one of our upcoming Webinars or access our archive of past Webinars to view recordings of presentations that may be of interest to you. Read More
Syngenta Sign
Seed/BiotechSyngenta Responds To Lawyer’s Victory Claim In Vi…
May 18, 2015
A plaintiff’s lawyer has issued a public statement claiming that damages have been awarded in the Agrisure Viptera corn lawsuits Read More
StewardshipCould Australian Water Trading Approach Fit In Californ…
May 18, 2015
Ten years of drought isn’t a good thing. It doesn’t help the bottom line of farmers or the health of Read More
SpreadersDutch Sprayer Manufacturer To Enter U.S. Market
May 18, 2015
Dutch self-propelled sprayer manufacturer Agrifac Machinery has announced intentions to enter the U.S. market with two models of sprayers available Read More
FertilizerTFI Weighs In On Fertilizer Rail Transport Bill
May 14, 2015
With today’s House Committee on Transportation and Infrastructure as a backdrop, The Fertilizer Institute (TFI) registered its support for policies Read More
ManagementA Visit To The 2015 Environmental Respect Spirit Award …
May 14, 2015
CropLife’s Paul Schrimpf and Eric Sfiligoj talk about a recent visit to the CPS Spirit winner in St. Stephen’s Church, Read More
StewardshipBayer Entomologist Issues Statement On Annual Honeybee …
May 13, 2015
Richard (Dick) Rogers, Principal Scientist / Entomologist, Bayer Bee Care Center for Bayer CropScience LP, today issued the following statement Read More
Crop InputsKansas State Researchers Announce Resistant Kochia Brea…
May 13, 2015
Kansas State University researchers say new research helps explain why an invasive weed is developing resistance to a well-known herbicide, Read More
RR2X soybeans surround untreated check (center)
HerbicidesUSDA Study: Glyphosate Application More Prevalent In So…
May 13, 2015
Glyphosate—known by many trade names, including Roundup—has been the most widely used pesticide in the United States since 2001. It Read More
AdjuvantsHelena Chemical Introduces New Drift Control Adjuvant J…
May 13, 2015
Helena Chemical Co. introduces Justified, an innovative drift control agent designed to improve the performance and precision of spray applications Read More
CropLife 100North Central Farmers Elevator, Wheat Growers Unificati…
May 13, 2015
The Boards of Directors for North Central Farmers Elevator (NCFE) and Wheat Growers (WG) have voted to approve the Unification Read More