Weeds In Waiting

Giant ragweed

This winter, dealers and growers may be trying to decide if dry weather, herbicide resistance, or poor application timing caused unacceptable weed control last year. No matter the cause, more weeds in the seed bank will mean more plants in 2008, says Jeff Stachler, Extension program specialist with The Ohio State University.

Bill Johnson, weed specialist with Purdue University, says a dry spring in Indiana in 2007 led to erratic and sometimes poor performance of soil-applied herbicides, as they weren’t activated by rainfall. “And it was so hot and dry later that weeds that are a problem to control anyway — including common lambsquarters, giant ragweed, and morningglory — weren’t controlled because they were hardened off by the drought.”

Ohio saw a similar weather and control scenario, reports Stachler. Giant ragweed hit corn hard, while soybean fields also saw common ragweed, common lambsquarters, velvetleaf, and common pokeweed.

Could resistance be playing a role? “I think glyphosate resistance is confusing to growers compared to ALS resistance,” says Johnson. “Glyphosate resistance is difficult to diagnose because we are dealing with low levels of resistance. This means that weeds will be injured by glyphosate, and whereas ALS resistance is clear-cut, weeds show very little injury by a glyphosate herbicide. Growers often think their herbicide failure is weather-related, or a result of a misapplication, and they may be surprised at how much resistance is out there.” Fourteen counties in Indiana now have confirmed glyphosate resistance in giant ragweed, and the problem will only continue to expand if growers do not manage this weed more aggressively, he says.

In addition, it appears that increasing percentages of Indiana’s growers planting glyphosate-tolerant corn were not using residual herbicides or lower rates of residual herbicides.

“I have a great deal of concern about the minor yield losses that are occurring because of early-season weed competition before glyphosate is applied in corn, and the growers may be thrilled with 200 bushels per acre corn when they could have had 210 to 220 with a more aggressive approach to weed management,” he says.

Johnson hopes that because corn prices were high, growers can invest some of that income on these products “to get 10 to 15 more bushels per acre this year.”

Johnson is encouraged that residual herbicide use is, in general, higher in corn than in soybeans. “The problem with corn is that there is such a narrow window to put on postemerge products, because the crops outgrow sprayers or labels,” he says. Plus, weed infestations can be difficult to see from the road.

For 2008, “we’ve had plenty of precipitation, our groundwater has been recharged, and we’re going into spring with normal soil moisture.” That’s good news for soil-applied herbicides.

Ragweed and Volunteer Problems

“Giant ragweed has the greatest potential to be a problem in Ohio because of how much went to seed in corn and soybeans due to improper application timing and herbicide resistance,” says Stachler. He also anticipates a ragweed problem as growers switch back to normal soybean acreage in 2008. “The giant ragweed that went to seed last year in corn will cause more problems in soybeans because some will be resistant,” he explains. In fact, he’s seen more stacked resistance: ALS/glyphosate-resistant giant ragweed, common ragweed, and marestail.

Officially, glyphosate resistance has not been documented in Iowa, but there are plenty of stories throughout the state “that strongly support the supposition that resistant weed populations exist in Iowa,” says Michael Owen, Extension weed management specialist, Iowa State University. Suspects for resistance include giant ragweed, marestail, and common lambsquarters, but recent control problems with common waterhemp should also concern growers.

Use of glyphosate has also caused volunteer crop management issues, Owen says. Spring conditions in Iowa in 2007 were not ideal, calling for replanting in many corn acres. Growers had to make sure to destroy stands that possessed herbicide resistance traits.

“I view volunteer Roundup Ready (RR) corn as a huge problem,” says Kevin Bradley, Extension weed specialist at the University of Missouri. And Dawn Refsell, University of Illinois Extension specialist, says her growers may see more volunteer RR corn in both corn and soybeans.

Waterhemp Woes

The “comer” weed for 2007 in both Illinois and Missouri seemed to be waterhemp. “Our newest problem is glyphosate-resistant waterhemp,” says Refsell. “This weed is going to change how we currently manage our soybean acres. We’ll no longer be able to rely on total postemergence glyphosate applications — growers are going to need the addition of preemergence chemicals and tank mixes.”

Velvetleaf may be showing some ALs resistance, causing trouble for soybean growers.elvetleaf may be showing some ALs resistance, causing trouble for soybean growers.
Velvetleaf may be showing some ALs resistance, causing trouble
for soybean growers.elvetleaf may be showing some
ALs resistance, causing trouble for soybean growers.

Illinois also faces combination resistances in waterhemp in the ALS, triazine, and PPO chemical classes; “our options for controlling waterhemp in soybean are getting limited to preemergence products only,” he explains.

“It would only help our situation if in fact we have less soybean planted next year,” says Missouri’s Bradley. “I’m not sure that’s going to happen. We’re a heavy soybean state, and we had a slight drop in soybean acreage last year but not as much as expected.”

In 2008, growers in Illinois should also be on the lookout for common lambsquarters, giant ragweed, morningglory, and marestail. Bryan Young, professor of weed science at Southern Illinois University, reports these weeds, as well as waterhemp, saw inconsistent foliar control with glyphosate products. He says: “I’m afraid we may have widespread problems in 2008.”

Cotton Concerns

In North Carolina, glyphosate-resistant Palmer amaranth has been identified in at least 11 counties, says Alan York, Extension specialist, North Carolina State University. “Unfortunately, ALS inhibitors in cotton have always been marginal on Palmer, and ALS-resistant Palmer is widespread in the Southeast. That exacerbates glyphosate resistance concerns,” he says.

But York is encouraged that growers did better with the weed in 2007 than 2006, and believes better control came from “a greater awareness of the problem and greater use of other herbicides within Roundup Ready systems – plus rotating out of some bad fields.”

Indeed, North Carolina cotton acreage was cut roughly in half in 2007 as more growers planted corn. York says the switch may have helped, as good control options are available in corn. Cotton acreage will likely drop again for 2008, with wheat being planted in highway medians and “everywhere else this winter,” says York — followed by double-cropped soybeans, also a crop with some good Palmer control choices. “The good — or bad — thing about weeds,” he notes, “is that they will handle whatever weather we have pretty well. That gives guys like me job security.”

Leave a Reply

Herbicides Stories

HerbicidesExpert: IARC Herbicide Classifications Leading To Confusion, Misinformation
July 24, 2015
Few people in the crop protection industry had heard of the International Agency for Research on Cancer (IARC) before this Read More
Palmer pigweed seedhead in cotton
HerbicidesUSDA Deregulates Dow AgroSciences’ Enlist Cotton Trait
July 23, 2015
The USDA today issued its decision deregulating Dow AgroSciences’ Enlist cotton trait in the U.S. The USDA has now completed its Read More
HerbicidesNufarm Releases New Panther SC Herbicide
July 23, 2015
Nufarm has announced the availability of new Panther SC herbicide. Panther SC is the first liquid formulation of flumioxazin available Read More
HerbicidesCould The South’s Most Troublesome Weed Represent A Threat To The Midwest Farm Belt?
July 22, 2015
Palmer amaranth is undoubtedly the most troublesome weed in the southern United States, taking a devastating toll on both cotton Read More
Top 100 Articles
CropLife 100Pinnacle Purchases California-Based Specialty Crops Retailer
July 20, 2015
Pinnacle Agriculture Holdings has successfully acquired California-based NH3 Service Co.  Operating as part of Pinnacle’s Performance Agriculture brand, the new locations Read More
Asmus Farm Supply liquid fertilizer facility features 20,000 square feet
CropLife 100Slideshow: Asmus Farm Supply Shows Off Its New Liquid Fertilizer Facility
July 15, 2015
Asmus Farm Supply, Rake, IA, recently added a new liquid fertilizer facility to its company operations. The new liquid fertilizer Read More
CropLife 100Wilbur-Ellis Feed Division Facilities Receive Safe Feed/Safe Food Certification
July 13, 2015
Wilbur-Ellis Co.’s Feed Division, a marketer and distributor of value-added feed ingredients for the aquaculture, livestock and pet food industries Read More
CropLife 100BRANDT Expands To Brazil With Acquisition
July 8, 2015
BRANDT has acquired a majority interest in Target Brasil Fertilizantes Ltda. through its Brazilian subsidiary. Target Brasil manufactures, distributes and Read More
Milan Kucerak, president/CEO, West Central
CropLife 100West Central Cooperative And Its New President Are A Match Made In Deviation
June 29, 2015
To appreciate just how unique West Central Cooperative is in the world of ag retail, an observer need only consider Read More
Winter Wheat
CropLife 100South Dakota Co-op Member Owners Vote No On Unification
June 26, 2015
The Boards of Directors for North Central Farmers Elevator (NCFE) and Wheat Growers (WG) have announced that member-owners have voted Read More
Latest News
StewardshipOhio Water Quality Project To Determine How Much Phosph…
July 27, 2015
Researchers with the College of Food, Agricultural, and Environmental Sciences at The Ohio State University are looking for farmers in Read More
FertilizerKoch Agronomic Services Launches N-TEGRATION Technology
July 27, 2015
Koch Agronomic Services, LLC (KAS) has launched  N-TEGRATION Technology, a process technology platform designed to enable production of enhanced efficiency fertilizers at Read More
HerbicidesExpert: IARC Herbicide Classifications Leading To Confu…
July 24, 2015
Few people in the crop protection industry had heard of the International Agency for Research on Cancer (IARC) before this Read More
ManagementFCI Trade Summit Update & Precision Tank Turns 50
July 23, 2015
Editors Dave Frabotta and Eric Sfiligoj discuss the upcoming FCI Trade Summit in Las Vegas, NV, and how Precision Tank Read More
Palmer pigweed seedhead in cotton
HerbicidesUSDA Deregulates Dow AgroSciences’ Enlist Cotton Trait
July 23, 2015
The USDA today issued its decision deregulating Dow AgroSciences’ Enlist cotton trait in the U.S. The USDA has now completed its Read More
Industry NewsVerdesian Life Sciences Showcases Versatile Product Por…
July 23, 2015
Technology has revolutionized agriculture by bringing farmers, retailers and distributors to the forefront of the digital age. To meet the Read More
FertilizerWSJ: Cf Industries Exploring Merger With Dutch Chemical…
July 23, 2015
U.S. fertilizer maker CF Industries is in advanced merger talks with Amsterdam-listed chemical company OCI NV, the Wall Street Journal Read More
HerbicidesNufarm Releases New Panther SC Herbicide
July 23, 2015
Nufarm has announced the availability of new Panther SC herbicide. Panther SC is the first liquid formulation of flumioxazin available Read More
EquipmentFarmLink Launches Farm Equipment Sharing Program
July 23, 2015
FarmLink has introduced a new online farm equipment sharing community – MachineryLink Sharing – leveraging this new economy business model Read More
HerbicidesCould The South’s Most Troublesome Weed Represent A Thr…
July 22, 2015
Palmer amaranth is undoubtedly the most troublesome weed in the southern United States, taking a devastating toll on both cotton Read More
Industry NewsH.J. Baker Hires New Director Of International Sales
July 22, 2015
Global Agriculture firm H.J. Baker announced today that Steve Langley has joined the company’s Crop Performance Division and Animal Health Read More
InsecticidesSyngenta Recommends Soybean Scouting To Prevent Economi…
July 22, 2015
Proper soybean insect pest control begins with scouting. As the warm weather continues, Syngenta encourages growers to implement a scouting Read More
Crop InputsH.J. Baker Launches Fall Sulphur Campaign
July 22, 2015
H.J. Baker has launched their “Keep Your Future Green – Use Tiger This Fall and Win Big” campaign. The campaign Read More
Central Valley Ag Randolph, NE
Retail FacilitiesStueve Construction Builds Fifth Facility For Central V…
July 21, 2015
Central Valley Ag partnered with Stueve Construction Co. to successfully design and build its Monroe, Oakland, Wakefield and Royal hub facilities Read More
FertilizerNew Research Could Lead To Less Reliance On Nitrogen, E…
July 21, 2015
Farmers often are required to apply nitrogen fertilizers to their crops to maintain quality and improve yields. Worldwide, farmers used Read More
Seed/BiotechMonsanto Targets Farmers, AFBF In Syngenta Takeover
July 21, 2015
As Monsanto Co. struggles to convince rival Syngenta AG to discuss a potential merger, the seed and agrochemical giant is Read More
CHS Building exterior
Retail FacilitiesSackett Helps CHS Expand Blending Facility, Improve Acc…
July 21, 2015
CHS needed a blend plant that could vastly expand their capabilities in St. Charles, MN. The A.J. Sackett & Sons Read More
Industry NewsH.J. Baker Adds To HR Team
July 21, 2015
H.J. Baker announced today that Barbara Sullivan has joined the company’s executive team as Vice President of Human Resources. Prior Read More