Precautions With Late-Season Herbicide Applications

The adverse environmental conditions common across much of Illinois are challenging the performance of many foliar-applied soybean herbicides.

Weeds that survive an initial herbicide application are often resprayed later in the season. However, according to University of Illinois associate professor of weed science Aaron Hager, the likelihood of controlling larger, moisture-stressed weeds continues to decline.

Moreover, herbicides applied late in the season are more likely to persist long enough to injure sensitive rotational crops. Nearly all herbicide labels (soil-applied or postemergence) specify the interval between herbicide application and planting a rotational crop. Some of these restrictions are based solely on time, while others take into account factors such as soil pH and the amount of precipitation received after herbicide application when determining interval length.

“Soil moisture is often the most critical factor governing the efficacy and persistence of soil-residual herbicides,” Hager said. “Many herbicides are degraded in soil by the activity of soil microorganisms, and populations of these microorganisms can be greatly depressed when soil moisture is limited.”

Dry soils can also enhance herbicide adsorption to soil colloids, thus rendering the herbicide unavailable for plant uptake and degradation by soil microbial populations. Some herbicide rotational intervals are increased if a specified amount of precipitation is not received by a certain calendar date.

The intervals are established to prevent herbicide residues from reaching levels that will adversely affect the rotational crop. Respecting these intervals becomes particularly important with late-season herbicide applications and when soil moisture is limited.

“Please keep in mind that the labels of almost all postemergence soybean herbicides indicate a preharvest interval or a soybean developmental stage beyond which applications cannot be made,” said Hager.

Labels of some products may indicate both a developmental stage (before soybean bloom, for example) and a preharvest interval. Preharvest intervals indicate the amount of time that must elapse between the herbicide application and crop harvest.

Failure to observe the preharvest interval may result in herbicide residue levels in the harvested portion of the crop in excess of established limits. Moreover, labels on many postemergence soybean herbicides specify that foraging of, or grazing livestock on, treated soybean is not allowed.

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 100Southern States Coop Hosting Drone Flight This Friday
August 3, 2015
Southern States Cooperative — No. 9 on the CropLife 100 — is hosting an FAA-approved drone demonstration at Grandview Farms Read More
CropLife 100Aligned Ag Distributors Adds Four New Owners
July 30, 2015
Aligned Ag Distributors LLC has announced the addition of four new customer/owners to Franklin Holding Co. LLC. They are: The Read More
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
Latest News
StewardshipOhio Grower: Why Water Quality Matters To Me
August 3, 2015
Fresh off the first anniversary of last summer’s unfortunate Toledo Water Crisis — which was largely attributed in mainstream media Read More
Young soybean field
Industry NewsH.J. Baker To Build New Facility In Emporia, KS
August 3, 2015
H.J. Baker has announced the expansion of its Animal Health and Nutrition division with the ground breaking of a new Read More
Young corn plants
Crop InputsNufarm Reorganizing Ag, Industrial Vegetation Managemen…
August 3, 2015
Today Nufarm announced a reorganization of its Agriculture and Industrial Vegetation Management sales and marketing organizations effective August 1, 2015. Read More
StewardshipExcellence Through Stewardship Reaches 30 Members
August 3, 2015
Excellence Through Stewardship, a non-profit that promotes the adoption of best practices and stewardship in agricultural technology, reached the milestone Read More
CropLife 100Southern States Coop Hosting Drone Flight This Friday
August 3, 2015
Southern States Cooperative — No. 9 on the CropLife 100 — is hosting an FAA-approved drone demonstration at Grandview Farms Read More
CropLife 100Aligned Ag Distributors Adds Four New Owners
July 30, 2015
Aligned Ag Distributors LLC has announced the addition of four new customer/owners to Franklin Holding Co. LLC. They are: The Read More
FungicidesReport: Sudden Death Syndrome Symptoms Appearing In Soy…
July 30, 2015
Last week, symptoms of sudden death syndrome (SDS) began to appear in April 15-planted soybeans at the University of Illinois’s Read More
Seed/BiotechAdvanta Seeds Adds New Phoenix Corn Hybrids
July 30, 2015
Corn growers in the High Plains and Western states have new options available for the 2016 growing season from Advanta Read More
ManagementTechnology and agriculture: a Futurist’s Perspective
July 30, 2015
Futurist David Zach, speaking at this week’s InfoAg Conference in St. Louis, shared thoughts on the benefits and limitations of Read More
Biofuels Plant in Lousiana
Industry NewsIdle Biofuels Plant In Louisiana To Reopen As Ammonia F…
July 30, 2015
A Lithuania-based company plans to spend $265 million to reopen an idle biofuels refinery in Grant Parish as an ammonia Read More
FFA at Monsanto Booth at the 2015 National Farm Machinery Show
Industry NewsFive Students Receive The 2015 Monty’s Plant Food Compa…
July 29, 2015
This fall, five college-bound students will have financial support through the Monty’s Plant Food Company FFA Scholarship. All five scholarship Read More
GYPSOIL Blendable Pellets
Crop InputsBeneficial Reuse Management Launches Pelletized Gypsum …
July 29, 2015
Beneficial Reuse Management (BRM) announced this week at Ag Media Summit that its GYPSOIL Pelletized Products Division will open a Read More
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