Specialist: Residual Herbicides No Match For Wet Soil

Soil-applied herbicides can knock out a grower’s toughest weeds but the chemical products are no match against soggy fields, says Bill Johnson, Purdue University Extension weed specialist.

A wet early spring has made it difficult for crop producers to apply soil-applied, or residual, herbicides to their fields ahead of planting. Producers should not push the envelope on herbicide treatments while fields are holding too much water, Johnson says.

“If it’s dry enough to plant, it’s dry enough to spray,” Johnson says. “We don’t plant our crops when soil conditions are such that we’re dropping the seed into mud, so we don’t want to apply our herbicides onto muddy ground, either.

“We run into challenges when we apply to fields that are too wet. One, we’re going to leave ruts in the field. Two, all herbicides are labeled such that they cannot be applied to standing water anyway. If we want to get the most out of our soil-applied herbicides, we need to put them on in conditions similar to those in which we would plant the crops.”

As their name suggests, soil-applied herbicides are sprayed on the soil before, during or just after crops are planted. While too much water nullifies their effectiveness, most residual herbicides need some soil moisture in order to work properly.

The herbicides are activated by moisture within the soil and are then absorbed by weed seedlings. Weed growth stops or is stunted, leading to plant death shortly after it emerges.

“A residual herbicide will have activity in the soil anywhere from about one to six weeks after application, depending on the product that you use,” Johnson says. “So what you essentially get, then, is herbicide activity that you don’t really see, because you have fewer weeds coming up. The weeds that do emerge from that residual system are going to be a little bit easier to control with your post-emerge herbicides.”

Excessive wetness isn’t the only challenge to using soil-applied herbicides. Johnson say growers should be careful to:

  • Choose the right residual product. “You have to know which weeds you’re going after,” Johnson says. “The most effective residual herbicides are going to be matched to the weed species that are in that field. For instance, if you have a giant foxtail weed problem, using a broadleaf herbicide is not going to be of much value in that field. You want to use a herbicide that’s active against grass weeds.”
  • Apply at the proper carrier volume. Johnson says glyphosate is one of the few foliar herbicides that works well at carrier volumes of 15 gallons per acre or less, which is why it is often tank mixed with residual herbicides. Contact herbicides, such as paraquat or Gramoxone, require 15-20 gallons per acre, he said.
  • Avoid applying in windy conditions, to prevent spray drift.
  • Rotate between products and weed control practices, to minimize the development of herbicide resistance.

“More than 90 percent of our soybeans and 70 percent of our corn are glyphosate- or Roundup-tolerant crops, so it’s going to be important for us to treat that technology as an investment,” Johnson said. “We want to keep that technology around for as long as possible, and the way we do that is to minimize selection pressure for glyphosate-resistant weeds.

“Using the appropriate residual herbicide on your worst weed problems and then saving glyphosate for the post-emerge cleanup treatment, is going to be the best way to protect crop yields and slow the development of glyphosate-resistant weeds.”

For more information on weed control in agricultural crops, visit the Purdue Weed Science Web page.

(Source: Purdue University)

Leave a Reply

Herbicides Stories
HerbicidesScouting Key To Next Season’s Soybean Herbicide Program
August 12, 2014
When growing soybeans, growers need to think ahead to stay one step ahead of weeds. That means examining weed threats and evaluating which herbicides work best. Read More
Winter Wheat
HerbicidesArysta Touts Burndown Herbicide For Brome Management In Wheat
June 4, 2014
Arysta LifeScience North America recommends PRE-PARE Burndown Herbicide for effective brome management in winter wheat. Read More
HerbicidesFall Herbicide Applications More Effectively Manage Resistant Italian Ryegrass
May 14, 2014
Field studies show that a fall application of certain herbicides before weed emergence, leads to more successful crop planting and weed control in spring. Read More
Waterhemp in soybean stubble
HerbicidesThe Weed Resistance Problem: A Matter Of Billions
April 1, 2014
Not only is the amount of money being spent to control these yield robbers high, but the toll it has taken on the human population is growing lager by the day. Read More
Top 100 Articles
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
CropLife 100Wilbur-Ellis Acquires South Dakota Retailer
April 2, 2015
Wilbur-Ellis Co.’s Agribusiness Division, a recognized leader in precision agriculture technology and the distribution and marketing of plant protection, seed Read More
CropLife 100The McGregor Co. Closes Smith-Kem Acquisition
April 2, 2015
The McGregor Co. — ranked No. 16 on the CropLife 100 list of largest U.S. ag retailers — has completed Read More
CropLife 100BRANDT Commemorates National Ag Day
March 20, 2015
The Illinois agriculture community gathered at BRANDT global headquarters on March 18 to celebrate National Ag Day behind this year's theme Sustaining Future Generations. Read More
Latest News
Cornfield near Sioux City Iowa
HerbicidesU.S. Regulators May Start Testing Food For Glyphosate R…
April 21, 2015
U.S. regulators may start testing food products for residues of the world’s most widely used herbicide, EPA told Reuters’ Carey Read More
FungicidesBRANDT Adds Zonix Biofungicide To Portfolio
April 21, 2015
BRANDT has added Zonix biofungicide to its rapidly expanding line of organic and sustainable products. Zonix is a contact fungicide that Read More
ManagementMissouri Experts: Spring Planting Slow Start Won’…
April 20, 2015
In the first of the agronomy teleconferences with Extension specialists, University of Missouri Extension climatologist Pat Guinan said the slow Read More
Carl Casale of CHS
Industry NewsCooperative CHS Reports Net Income Of $471.5 Million Fo…
April 20, 2015
CHS Inc., the nation’s leading farmer-owned cooperative and a global energy, grains and foods company, has announced company net income Read More
Industry NewsCHS Insurance Names New Director Of Sales
April 17, 2015
Bryan Lewis has been named director of sales for CHS Insurance, the nation’s largest agribusiness insurance broker and full-service insurance Read More
Mature Waterhemp in Corn
HerbicidesGenetic Literacy Project: There’s No Such Thing A…
April 17, 2015
Read the latest “analysis” on GMOs from Consumer Reports and you’ll “learn” that glyphosate, the chemical developed by Monsanto (its Read More
HerbicidesNew Resistance To 2,4-D Discovered In Australia
April 17, 2015
In a world-first case of herbicide resistance, researchers have confirmed that sowthistle weed in the south east of South Australia Read More
ManagementNews From RTP Company Visits and Growers Buying Older S…
April 16, 2015
Paul Schrimpf and Eric Sfiligoj discuss recent trips to the Research Triangle Park area and market seed sales trends. Read More
soybean field
StewardshipNew ASABE Standard Establishes Framework For Sustainabl…
April 16, 2015
The American Society of Agricultural and Biological Engineers (ASABE) has initiated a project to develop a new standard to establish Read More
MicronutrientsSouthern States: An Inside Look At Our Tissue Sampling …
April 15, 2015
Remember learning about the food pyramid in school? The nutritional diagram recommends the proper amount of nutrients you need on Read More
Industry NewsArysta Adds New U.S. Fungicides Marketing Manager
April 15, 2015
Arysta LifeScience North America recently hired Deneen Sebastian as its Marketing Manager for U.S. Row Crops, Fungicides. Most recently, Sebastian Read More
FungicidesVerdesian Launches Phosphite-Based Cereal Fungicide
April 14, 2015
A new, phosphite-based fungicide designed for improved suppression of deoxynivalenol (DON) in wheat and barley infected by Fusarium head blight Read More
Mature Waterhemp in Corn
HerbicidesSURVEY: Close To 90% Of Growers Battle Weed Resistance
April 14, 2015
Herbicide resistance management continues to be a priority for corn and soybean growers, and they’re working together more effectively to 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
StewardshipFMC Corp. Joins Sustainable Agriculture Alliance
April 14, 2015
FMC Corp. has joined Field to Market: The Alliance for Sustainable Agriculture, a multi-stakeholder initiative working to define, measure and Read More
Industry NewsArysta Adds Two To Goëmar Sales Team
April 14, 2015
Arysta LifeScience North America recently announced two new additions to the Goëmar sales team: Steve Kelly, Technical Service Manager – Read More
Valley Variable Rate Irrigation
Precision AgVariable Rate Irrigation Gains Followers
April 14, 2015
Irrigation systems have had the ability to apply different amounts of water throughout a field for decades, using timers that Read More
CropLife 100CHS, Aurora Cooperative Complete Fertilizer Storage, Gr…
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