Palmer Amaranth Recommendations For 2014 Growing Season

Palmer amaranth is a weed species that must be thoughtfully and carefully managed. Simply attempting to control Palmer amaranth often leads to ineffective herbicide applications, substantial crop yield loss, and increased weed infestations, said University of Illinois weed sciences researcher Aaron Hager.

“If ignored or otherwise not effectively managed, Palmer amaranth can reduce corn and soybean yield to nearly zero,” Hager said. “The threat of Palmer amaranth during the 2014 growing season is very real across a large portion of Illinois.”

The University of Illinois weed science program has developed recommendations for management of Palmer amaranth in agronomic crops. These recommendations were developed in accordance with the unique growth characteristics of this weed species. The goals of the recommendations are two-fold: to reduce the potential for Palmer amaranth to negatively impact crop yield, and to reduce Palmer amaranth seed production, which ultimately augments the soil seed bank and perpetuates the species.

Three general principles of Palmer amaranth management include:

• Prevention is preferable to eradication. Prevention refers to utilizing tactics that prevent weed seed introduction and weed seed production.

“Palmer amaranth is not native to Illinois so any population discovered in the state originated from seed that somehow was moved into the state,” Hager said. “The myriad of ways in which Palmer amaranth seeds can be transported, however, makes preventing seed introduction extremely challenging. Once Palmer amaranth populations become established, utilizing any and all tactics to prevent seed production becomes of paramount importance.”

• It is not uncommon for annual herbicide costs to at least double once Palmer amaranth becomes established. There are simply no soil- or foliar-applied herbicides that will provide sufficient control of Palmer amaranth throughout the entire growing season.

• Control of Palmer amaranth should not be less than 100%.

“In other words, the threshold for this invasive and extremely competitive species is zero,” the researcher said. “Female Palmer amaranth plants produce tremendous amounts of seed, and in less than five years a few surviving plants can produce enough seed to completely shift the weed spectrum in any particular field.”

Recommendations based on Palmer amaranth germination and emergence characteristics include:

• Be certain to control all emerged Palmer amaranth plants before planting corn or soybean. Burn-down herbicides or thorough tillage are effective tactics to control emerged Palmer amaranth plants before planting. Keep in mind, however, that glyphosate will not control glyphosate-resistant Palmer amaranth and that growth regulator herbicides (such as 2,4-D or dicamba) are most effective on Palmer amaranth plants less than 4 inches tall. If pre-plant scouting (which is especially important prior to planting soybean) reveals Palmer amaranth plants taller than 4 inches, consider using tillage instead of herbicides to control the plants.

• Apply a full rate (based on label recommendations for soil texture and organic matter content) of an effective soil residual herbicide no sooner than seven days prior to planting and no more than three days after planting. Many soil residual herbicides that are effective for controlling waterhemp are also effective for controlling Palmer amaranth. In soybeans, products containing sulfentrazone (Authority) or flumioxazin (Valor) have provided effective control of Palmer amaranth. Application rates of products containing these active ingredients should provide a minimum of 0.25 lb ai/acre sulfentrazone or 0.063-0.095 lb ai/acre flumioxazin.

Hager said growers should not rely solely on glyphosate to control Palmer amaranth. “Molecular assays have indicated that resistance to glyphosate appears to be relatively common among recently identified Palmer amaranth populations in Illinois,” he explained.

Recommendations based on Palmer amaranth growth rate include:

• Begin scouting fields within 14 to 21 days after crop emergence. “We recommend this interval even for fields previously treated with a soil residual herbicide applied close to planting,” he explained.

• Foliar-applied herbicides must be applied before Palmer amaranth plants exceed 4 inches in height. The effectiveness of most foliar-applied herbicides dramatically decreases when Palmer amaranth plants are taller than 4 inches. Postemergence herbicides that demonstrate control or suppression of Palmer amaranth include synthetic auxin herbicides (dicamba, 2,4-D), diphenylethers (acifluorfen, lactofen, fomesafen), glufosinate, glyphosate, and HPPD inhibitors (mesotrione, tembotrione, topramezone).

• Consider including a soil residual herbicide during the application of the foliar-applied herbicide. A soil residual herbicide applied with the foliar-applied herbicide can help control additional Palmer amaranth emergence and allow the crop to gain a competitive advantage over later-emerging weeds.

• Fields should be scouted 7 to 14 days after application of the foliar-applied herbicide to determine herbicide effectiveness; if the soil residual herbicide included with the post application is providing effective control; and if additional Palmer amaranth plants have emerged.

“If scouting reveals additional Palmer amaranth plants have emerged, make a second application of a foliar-applied herbicide before Palmer amaranth plants are 4 inches tall,” Hager said.

In regard to Palmer amaranth seed production, Hager said research has demonstrated that female Palmer amaranth plants are capable of producing numbers of seed comparable to that of waterhemp (several hundred thousand to over one million). “Physically remove any remaining Palmer amaranth plants before the plants reach the reproductive growth stage. Plants should be severed at or below the soil surface and carried out of the field. Severed plants can root at the stem if left on the soil surface, and plants can regenerate from stems severed above the soil surface,” he said.

Source: Illinois Ag Connection

Topics:

Leave a Reply

Crop Inputs Stories

Syngenta Seedcare Institute
Seed/BiotechSyngenta Opens New North America Seedcare Institute In Stanton, MN
September 23, 2016
Syngenta unveiled its new Seedcare Institute in Stanton, MN, during a recent grand opening celebration. More than 150 industry leaders, Read More
Crop InputsJim Loar Promoted To President And CEO Of Cool Planet
September 22, 2016
In a move that reflects and reinforces the company’s commitment to the agricultural market, the Cool Planet board of directors Read More
Crop InputsMonsanto, Bayer Officials Defend Proposed $66 Billion Merger
September 21, 2016
Top officials for Monsanto and Bayer defended their proposed $66 billion merger before skeptical senators on Tuesday, insisting that the Read More
Corn
Crop InputsEPA Settles With Syngenta For Alleged Multi-Regional Pesticide Violations
September 19, 2016
The U.S. EPA has announced a multi-region settlement with Syngenta Crop Protection, LLC (Syngenta) in Greensboro, NC, for alleged violations of Read More
Trending Articles
Bayer Monsanto
Crop InputsBayer-Monsanto Mega-Merger: 6 Things You Need To Know
September 14, 2016
Mega mergers have become almost routine in the agricultural industry. Right on the heels of Monday’s news that fertilizer giants Potash Read More
Potash Corp Agrium
Crop InputsAgrium, Potash Corp To Merge To Create $36 Billion Company
September 12, 2016
Canada’s Agrium Inc. and Potash Corp of Saskatchewan Inc. have agreed to combine in a deal that would create a Read More
Osage Co-op Elevator Osage, IA Finished Building
OpinionAre We Crazy?
September 8, 2016
At some point in the first few months of my employment here at CropLife® magazine, I started getting curious about Read More
ManagementMAGIE 2016 Highlights and Deere Anti-Trust
September 1, 2016
CropLife Editor Eric Sfiligoj discusses the recent Midwest AG Industries Exposition and the Department of Justice’s objection to John Deere Read More
ASMARK 2016 Retailers Live! Tour - CPS
CropLife 100CPS Acquires Texas Retail Operation
August 23, 2016
Crop Production Services (CPS) has acquired the assets of Larry’s Chemical and Spray, Inc., for an undisclosed amount in an Read More
Key Cooperative Marcus Construction Steel Building
Retail FacilitiesMarcus Construction Builds High-Speed Agronomy Center For Key Cooperative
July 7, 2016
Key Cooperative in Grinnell, IA, wanted a state-of-the-art Agronomy Center to better serve its customers. Marcus Construction delivered exactly that. Read More
Latest News
Corn Field
Eric SfiligojFacing Ag Industry Challenges
September 26, 2016
At the 2016 annual Mid America CropLife Association (MACA) meeting in September, a pair of crop protection company representatives discussed Read More
Syngenta Seedcare Institute
Seed/BiotechSyngenta Opens New North America Seedcare Institute In …
September 23, 2016
Syngenta unveiled its new Seedcare Institute in Stanton, MN, during a recent grand opening celebration. More than 150 industry leaders, Read More
StewardshipMonsanto Invests $1.6 Million In System To Quantify Gre…
September 23, 2016
The USDA – Natural Resources Conservation Service (USDA-NRCS) recently awarded the National Corn Growers Association (NCGA) and its Soil Health Read More
Pipe rack
LegislationCourt Sides With Ag Retailers On PSM
September 23, 2016
The D.C. Court of Appeals has ruled the Occupational Safety and Health Administration violated the Occupational Safety and Health Act when Read More
ManagementPacific Coast Fertilizer Announces Interest In Longview…
September 22, 2016
Pacific Coast Fertilizer LP (PCF) announced at the Cowlitz Economic Development Council board of directors meeting its interest in developing Read More
Young corn plants in soil
UncategorizedCool Planet Raises Additional $9 Million To Commerciali…
September 22, 2016
Cool Planet has announced the first close of a new financing round to commercialize the company’s Cool Terra Engineered Biocarbon Read More
Crop InputsJim Loar Promoted To President And CEO Of Cool Planet
September 22, 2016
In a move that reflects and reinforces the company’s commitment to the agricultural market, the Cool Planet board of directors Read More
BlendersNorth Dakota Coop Debuts Dry Fertilizer Plant
September 22, 2016
North Central Grain Cooperative has begun operations at a new dry fertilizer plant at its Rolla, ND, site. It is Read More
Crop InputsMonsanto, Bayer Officials Defend Proposed $66 Billion M…
September 21, 2016
Top officials for Monsanto and Bayer defended their proposed $66 billion merger before skeptical senators on Tuesday, insisting that the Read More
ManagementUpcoming Shows & Recent Events
September 19, 2016
Editors Paul Schrimpf and Eric Sfiligoj talk about upcoming trade shows and events and review the Mid America CropLife Association Read More
Industry NewsVerdesian Life Sciences Appoints New CEO
September 19, 2016
Verdesian Life Sciences, a plant health and nutrition company, today announced that its board of directors has named Kenneth M. Avery Read More
Corn
Crop InputsEPA Settles With Syngenta For Alleged Multi-Regional Pe…
September 19, 2016
The U.S. EPA has announced a multi-region settlement with Syngenta Crop Protection, LLC (Syngenta) in Greensboro, NC, for alleged violations of Read More
ManagementMerger Mania
September 16, 2016
Editors Paul Schrimpf and Eric Sfiligoj discuss this week’s mega-ag mergers of Bayer and Monsanto and Potash and Agrium. Read More
Monsanto sign
Crop InputsMonsanto Ends Up Being A Bargain For Bayer
September 16, 2016
History will say Bayer got a bargain in its $66 billion purchase of Monsanto, writes David Nicklaus, St. Louis Post-Dispatch. The Read More
Greg Musson, Gar Tootelian
CropLife 100California Ag Retailer Steps Up To Feed Families Affect…
September 16, 2016
GAR Tootelian, Inc. (GAR) in Reedley, CA, is challenging the Central Valley to help raise enough money and provide 525,000 meals Read More
Crop InputsBayer, Monsanto CEOs Discuss Merger
September 15, 2016
Werner Baumann, Bayer CEO, and Hugh Grant, Monsanto CEO, discuss why they decided to merge their companies. Read More
Corn close up
Crop InputsNY Times: Bayer-Monsanto a Bad Deal for Farmers
September 15, 2016
Via NY Times: Don Halcomb, a 63-year-old farmer in Adairville, KY, is expecting his profit to vanish this year, largely Read More
Werner Baumann, Bayer AG, and Hugh Grant, Monsanto
Crop InputsBayer-Monsanto Merger Creates New Global Ag Giant
September 14, 2016
During the whole of 2016, many of the companies that do business in the agricultural industry have concluded the best Read More