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

Crop InputsFields of the Future: WinField Doubles Down with Agri-Education Center Investment (w/Photo Gallery)
June 16, 2016
Land O’Lakes, Inc., joined by Agriculture Secretary Tom Vilsack, today will host Fields of the Future, a live broadcast about Read More
Bayer sign
Crop InputsMonsanto Turns Back Bayer Again
June 14, 2016
Bayer AG’s bid to buy Monsanto Co. for more than $60 billion has hit an impasse that could pose a Read More
Young Corn Field
Crop NutritionNext Generation Of Nitrogen Efficiency Technology Converts Nitrogen To Bushels
June 13, 2016
Commodity price projections indicate farmers will continue to face tight margins again this year. Delivering higher yields and more bushels Read More
Aspire with Boron
Crop InputsStudy: Aspire with Boron Ups Alfalfa Yields
June 8, 2016
Alfalfa growers are successfully improving yields through the cutting season by applying an important micronutrient. In a recent study, The Read More
Trending Articles
Food IT
Industry NewsCalifornia Event Will Mix Ag And Tech Professionals To Explore IT Solutions
June 20, 2016
Silicon Valley is hot on agriculture, and an upcoming event in California will bring together the food and tech industries Read More
Monsanto Luling Plant
Eric SfiligojWhat’s Next For Monsanto?
May 31, 2016
For the folks at Monsanto’s headquarters in St. Louis, MO, it has been an eventful few weeks. Back on May Read More
Soybean Plant closeup
Industry NewsMonsanto Rejects Bayer Bid; Open To More Talks
May 25, 2016
Monsanto Co, the world’s largest seed company, turned down Bayer AG’s $62 billion acquisition bid as “incomplete and financially inadequate” Read More
Eric SfiligojPity The Monsanto Haters
May 23, 2016
An old saying goes thus: “Be careful what you wish for. You just might get it.” Given current events, there Read More
Monsanto Luling Plant
Crop InputsReport: Bayer Eyeing Monsanto For Possible Mega-Merger
May 16, 2016
Bayer AG is exploring a potential bid for U.S. competitor Monsanto Co. in a deal that would create the world’s Read More
Aerial Drone
Precision AgA Deeper Dive Into The Future Of Precision Ag
May 9, 2016
For about two decades now, through the good and the bad times, the ups and the downs inherent in agriculture, Read More
Latest News
Allen Summers Asmark Institute PSM Training
EmployeesAsmark Institute Sponsors 25 ResponsibleAg Auditor Trai…
June 21, 2016
The Asmark Institute has announced plans to provide 25 scholarships through their affiliated State fertilizer and agrichemical associations to help encourage Read More
Kennebec Elevator
CropLife 100Wheat Growers Celebrates Kennebec Elevator Grand Openin…
June 21, 2016
Over 250 patrons and guests were on hand to celebrate Wheat Growers’ Kennebec Elevator grand opening. South Dakota Secretary of Read More
Land O Lakes
Industry NewsLand O’Lakes To Acquire Ceres
June 20, 2016
Land O’ Lakes, Inc. and Ceres, Inc. have announced that they have signed a definitive merger agreement under which Land O’Lakes Read More
Food IT
Industry NewsCalifornia Event Will Mix Ag And Tech Professionals To …
June 20, 2016
Silicon Valley is hot on agriculture, and an upcoming event in California will bring together the food and tech industries Read More
LegislationVilsack Christens WinField Crop Adventure, Talks Monsan…
June 17, 2016
The WinField Crop Adventure grand opening ceremonies at Fair Oaks Farms (near Winemac, IN) welcomed USDA Secretary of Agriculture Tom Read More
Crop InputsFields of the Future: WinField Doubles Down with Agri-E…
June 16, 2016
Land O’Lakes, Inc., joined by Agriculture Secretary Tom Vilsack, today will host Fields of the Future, a live broadcast about Read More
Bayer sign
Crop InputsMonsanto Turns Back Bayer Again
June 14, 2016
Bayer AG’s bid to buy Monsanto Co. for more than $60 billion has hit an impasse that could pose a Read More
Young Corn Field
Crop NutritionNext Generation Of Nitrogen Efficiency Technology Conve…
June 13, 2016
Commodity price projections indicate farmers will continue to face tight margins again this year. Delivering higher yields and more bushels Read More
Industry NewsLa Crosse Seed Acquires Cover Crop Solutions Brand
June 10, 2016
La Crosse Seed announces that it is the new and exclusive owner of the entire family of brands of Cover Read More
ManagementTravel Plans and EU Rejection of Glyphosate, Biotech Cr…
June 9, 2016
Editors Paul Schrimpf and Eric Sfiligoj talk about upcoming trips and the latest in the European Union’s moves against glyphosate Read More
Aspire with Boron
Crop InputsStudy: Aspire with Boron Ups Alfalfa Yields
June 8, 2016
Alfalfa growers are successfully improving yields through the cutting season by applying an important micronutrient. In a recent study, The Read More
Industry NewsAGCO Announces Tragic Death of Longtime Employee
June 8, 2016
It is with deepest regret that we announce the passing of our dear friend, colleague and customer advocate-in-chief Kevin W. Read More
Wheat Field North Dakota
Industry NewsBASF Inks Northern Seed for Clearfield Wheat R&D Li…
June 6, 2016
BASF has licensed Northern Seed LLC to perform research and development of BASF’s proprietary and patented Clearfield technology in wheat. Read More
ManagementBayer/Monsanto, EU/Glyphosate, Corn/Soybeans
June 2, 2016
Editors Paul Schrimpf and Eric Sfiligoj discuss the latest regarding industry mergers, the glyphosate debate in Europe, and an update Read More
Growers looking at soybeans
Industry NewsKoch Licenses 2 Marrone Products For North American Dis…
June 2, 2016
Koch Agronomic Services (Koch), with support from its affiliate, Koch Biological Solutions, has secured exclusive rights to sell REGALIA Rx Read More
Gypsum
Industry NewsBeneficial Reuse Management Launches GYPSOIL BLENDABLE
June 2, 2016
Beneficial Reuse Management (BRM) has introduced GYPSOIL BLENDABLE, a new high-quality pelleted gypsum fertilizer that supplies 17% sulfate sulfur and Read More
StewardshipAgrible Joins Field To Market To Pursue Sustainable Sou…
June 1, 2016
Agrible, Inc. has joined Field to Market: The Alliance for Sustainable Agriculture as an associate member. As a leading multi-stakeholder Read More