Be Aware Of Potential For Herbicide Carryover

The effectiveness of soil-residual herbicides at controlling weeds has been reduced due to the dry soil conditions in most of Illinois during the 2012 growing season. Associate professor of weed science Aaron Hager warned that these conditions also slow the rate of herbicide degradation, increasing the likelihood that herbicide carryover could damage rotational crops.

“Once a herbicide is applied, there is little that can be done to shorten the time it remains active in the soil environment,” Hager said. “Herbicide persistence depends on the interaction of the herbicide’s characteristics, the soil, and climatic conditions.”

Characteristics of the herbicide molecules affect its persistence in the soil. Some herbicides, such as thifensulfuron, have very little soil persistence whereas others, such as picloram, can persist for several months.

“Soil persistence can also vary among herbicides within a particular chemical family,” Hager noted. “For example, within the imidazolinone herbicide family, soil persistence of imazamox is much shorter than that of imazethapyr.”

Chemical, physical, and microbial soil properties also influence herbicide persistence. For some herbicides, soil pH is important because it impacts how much herbicide is available for plant uptake and how quickly it is degraded by hydrolysis.

“For example, atrazine is more available for plant uptake when the soil pH is approximately 7.0 or higher,” Hager explained. “It also persists longer because the rate of hydrolysis slows at higher soil pH values. The degradation rate of many sulfonylurea herbicides slows with high soil pH values. Imidazolinone herbicides persist longer in soils with low pH values.”

Physical properties of soils, such as sand, silt, clay, and organic matter content, affect herbicide persistence. Soils with high clay and organic matter content adsorb more herbicide onto soil colloids than coarse-textured soils or soils with less organic matter.

“Herbicide bound to soil colloids cannot be taken up by plants, move downward through the soil profile, or be degraded by microbes,” said Hager. “Rotational crops can be injured when water molecules displace these bound residues late in the season or in the following spring.”

Soil microorganisms degrade many herbicides; the speed of degradation depends on the levels, species and activity of microorganisms. They work most efficiently when there is adequate soil moisture. Under extremely dry conditions, microbial degradation can slow enough to allow the herbicide to persist into the next growing season.

What can be done to minimize the risk of injury to rotational crops from herbicides applied this season?

“Apart from a return to normal or above normal precipitation amounts, there is little that can be done to accelerate herbicide degradation at this point,” said Hager. “Degradation requires time and moisture.”

Shallow tillage can help distribute herbicide more evenly across a field, but it will do little to accelerate herbicide degradation in extremely dry soil. If planting is early next season, the likelihood of crop injury from herbicide carryover could increase.

Planting the same crop that was planted in 2012 in the following season would eliminate the potential for crop injury from herbicide residues. This option may not be feasible for every situation where herbicide carryover is possible, but it warrants some consideration. If crop rotation must occur where there is a risk of herbicide carryover, delaying planting as long as possible could allow time for additional herbicide degradation.

“Several producers have asked about the feasibility of planting a cover crop, fall forage crop, or small-grain crop after the 2012 corn crop is harvested or destroyed,” Hager said. Most herbicide labels indicate the amount of time that must elapse between application and planting the rotational crop. Labels of most corn herbicides also indicate an interval that must elapse between application and harvest for grain, silage, or grazing.

“In many instances, the interval between application and winter wheat planting will not be long enough this year,” Hager warned. “Small-grain crops can be sensitive to even small amounts of residue herbicides, such as atrazine, that remain in the soil.”

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