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

Giant Ragweed
HerbicidesStudy: Focusing On Weed Seedbank Can Help Manage Herbicide-Resistant Giant Ragweed
January 18, 2017
Researchers writing in the latest issue of the journal Weed Science provide important insights on the control of herbicide-resistant giant Read More
HerbicidesEPA Expands Enlist Duo Herbicide Registration To 34 States
January 13, 2017
The U.S. EPA has expanded the geography for application of Enlist Duo herbicide from 15 to 34 states. This means Read More
HerbicidesHow Does Herbicide Resistance Evolve?
January 6, 2017
Herbicide-resistant weeds have evolved in response to repeated use of herbicides with the same site of action (SOA), according to Read More
Kochia
Herbicides9 Recommendations For Reducing The Risks Of Herbicide Resistance
January 5, 2017
To address the increasing urgent problem of herbicide resistance, the Weed Science Society of America makes the following recommendations: Reduce the Read More
Trending Articles
AgriSync
Matt Hopkins17 Agriculture Apps That Will Help You Farm Smarter In 2017
December 9, 2016
Ag professionals are working smarter, not harder, than ever before. Smart farming technologies have enabled them to reduce costs, maximize Read More
R4023 Sprayer, John Deere
CropLife 100Ag Retail Equipment Report: The Green Party Continues
December 7, 2016
In the annual race for sales in the ag retail equipment marketplace, the color schemes for participants are a little Read More
Mike Stern
Precision AgClimate Corp. CEO Talks Retailer Support For Digital Ag
December 1, 2016
CropLife Magazine’s sister publication, AgriBusiness Global, recently sat down with Mike Stern, CEO of The Climate Corp., following the Monsanto subsidiary’s Read More
Precision AgTrimble Debuts End-to-End FMIS Platform
November 28, 2016
October’s inaugural PrecisionAg Vision Conference left this author with many thoughts and things to ponder in the coming months. Probably Read More
CHS Primeland
CropLife 100The 2016 CropLife 100 Report: Reviewing The Many Bulls And Bears Impacting This Year’s Marketplace
November 28, 2016
For virtually all of 2016, the nation was wholly focused on the big Presidential election. Some folks aligned themselves with Read More
Monsanto sign
Crop InputsMissouri Governor Meets With Bayer CEO To Discuss Monsanto Merger
November 21, 2016
Missouri Gov. Jay Nixon visited Bayer AG global headquarters in Leverkusen, Germany, on November 18 to discuss the proposed Bayer-Monsanto Read More
Latest News
ManagementPresident Trump, Wisconsin Review, and a Dow-DuPont Upd…
January 18, 2017
Editors Paul Schrimpf and Eric Sfiligoj reflect on a new administration, a recent winter show, and crop protection company mergers. Read More
Industry NewsBayer, MS Technologies Get China Approval For Balance G…
January 18, 2017
MS Technologies and Bayer have received import approval from China for Balance GT soybeans. The new Balance GT Soybean Performance Read More
Werner Baumann, Bayer AG, and Hugh Grant, Monsanto
Industry NewsReport: Monsanto, Bayer CEOs Among Latest to Make Trump…
January 18, 2017
The chief executive officers of German chemical giant Bayer AG and U.S. seed behemoth Monsanto, Werner Baumann and Hugh Grant, Read More
Giant Ragweed
HerbicidesStudy: Focusing On Weed Seedbank Can Help Manage Herbic…
January 18, 2017
Researchers writing in the latest issue of the journal Weed Science provide important insights on the control of herbicide-resistant giant Read More
Management3 Financial Trends To Watch In Agriculture
January 17, 2017
I recently had the opportunity to attend a meeting of credit managers for Midwest ag supply and input companies, in part Read More
Andersons Retail Store
CropLife 100The Andersons To Close All Retail Stores; Shutdown Does…
January 16, 2017
In a stunning announcement to the Toledo area, The Andersons Inc. said on Sunday that it would close its two Read More
Trimble TMX-2050 In-Cab Display
Eric SfiligojPrecision To Lead Agriculture In 2017?
January 16, 2017
Another new year is upon us! And I’m certain I speak for many in the agricultural world when I say Read More
Corn
Eric SfiligojThe Mood From Madison? In A Holding Pattern
January 16, 2017
Last week, I had the chance to attend the annual Wisconsin AgriBusiness Classic show in Madison, WI. It’s been a Read More
Syngenta Sign
Crop InputsAccenture Helps Syngenta Transform Its Global Logistics
January 13, 2017
Syngenta, a leading agriculture company, has collaborated with Accenture to design and implement a new digital logistics operating model across Read More
Fall Creek Seth Harden The Nature Conservancy
StewardshipLocal Farmers’ Watershed Initiative: Continuous Improve…
January 13, 2017
The goal in the Big Pine Watershed Project is to more intentionally do what local farmers and responsible ag retailers Read More
HerbicidesEPA Expands Enlist Duo Herbicide Registration To 34 Sta…
January 13, 2017
The U.S. EPA has expanded the geography for application of Enlist Duo herbicide from 15 to 34 states. This means Read More
Olson Ag Enterprise
CropLife 100Wilbur-Ellis Acquires Nebraska Seed Retailer
January 13, 2017
Wilbur-Ellis’ Agribusiness, a recognized leader in precision agriculture technology and the distribution and marketing of plant protection, seed and nutritional Read More
ManagementDeere-Precision Planting Update and the Ag Secretary Wa…
January 12, 2017
Editors Paul Schrimpf and Eric Sfiligoj provide the latest on the court date for John Deere/Precision Planting and the quest Read More
Monsanto sign
Seed/BiotechMonsanto, NRGene Form Agreement For Big Data Genomic An…
January 12, 2017
Monsanto Co. and NRGene have announced that the companies have reached a non-exclusive, multi-year global licensing agreement on NRGene’s genome-analysis Read More
AGCO Custom applicator
SprayersAGCO, Asmark Institute To Offer Training For Beginning …
January 11, 2017
AGCO Corp. and the Asmark Institute are collaborating to offer a new training program dedicated to educating and developing custom Read More
ManagementAg Land Values In Limbo In 2017
January 10, 2017
Several factors will come into play in 2017 that will determine the direction of land values. Randy Dickhut, senior vice Read More
Industry NewsPattison Agriculture Positioned To Be Leading Canadian …
January 10, 2017
Pattison Agriculture Limited (Pattison Agriculture), a division of The Jim Pattison Group (the Pattison Group), has announced the merger of Read More
Fertilizer Tender close-up
MicronutrientsHow Micronutrients Fit Into 2017 Fertility Plans
January 10, 2017
Where do micronutrients stand going forward in fertility plans? For one thing, Tim Mundorf, Field Representative with Midwest Laboratories, says Read More