Key Factors Impacting Herbicide Injury To Corn

During the past week, the number of observations and inquiries related to corn injury from herbicides increased, said University of Illinois associate professor of weed science Aaron Hager.

Instances of corn injury appear to be fairly widespread across the state. Direct application of postemergence herbicides and persistence of herbicides applied last season appear to be responsible for much of the injury.

“Many postemergence corn herbicides routinely cause some corn injury,” said Hager. “Some growers, however, have the impression that this year there is a bit more injury than usual.”

Hager said that several factors can affect the sensitivity of corn to injury from postemergence herbicides, including:

  • Hybrid: Hybrids have varying sensitivity to herbicides labeled for use in corn. For example, some corn hybrids are sensitive to specific ALS-inhibiting herbicides and tend to exhibit considerable injury following herbicide application. Many corn herbicide labels (especially labels of postemergence corn herbicides) carry warnings that certain corn hybrids could be sensitive to the active ingredient.
  • Environmental conditions: High air temperatures and relative humidity levels favor rapid absorption of foliar-applied herbicides, but some environmental conditions can induce crop stress, slowing the rate at which the crops metabolize the herbicide and leading to increased herbicide-related injury. For example, cool air temperatures and wet soil can induce crop stress.
  • Spray additives: Crop response may be enhanced when spray additives are applied with a postemergence herbicide or tankmix combination because of the increased rate of herbicide absorption into the plant. Be sure to read all label suggestions and precautions related to spray additives that should be either included or avoided when applying herbicides postemergence.
  • Contamination: Herbicide residues from prior applications may be applied inadvertently with the postemergence corn herbicide. These residues, either alone or in combination with the postemergence corn herbicide, may enhance the amount of corn injury. The type of contaminant and the dose at which it is applied affect the severity of the corn response to spray contamination.

Soil residues of herbicides applied during the previous growing season (carryover) appear to be another source of corn injury. Herbicide persistence in the soil, and the rate of chemical or microbial degradation, are influenced by many factors, including the specific chemistry of the herbicide and edaphic factors.

The soil pH is a critical factor affecting the persistence and degradation of many herbicides, including sulfonylurea and triazine herbicides, because it affects the rate of chemical degradation via hydrolysis. High soil pH (7.0 or more) may slow the dissipation of certain herbicides by reducing the hydrolysis rate. Even when soil moisture is adequate, triazine and sulfonylurea herbicides degrade more slowly in soils with high pH.

Soil moisture also influences the efficacy and persistence of soil-residual herbicides. Populations and activity of soil microorganisms that are responsible for microbial degradation of herbicides are greatly reduced when soil moisture is limited. Moreover, more herbicide is adsorbed to soil colloids in dry soils, making it unavailable for plant uptake and degradation by soil microbial populations.

“The very dry soil conditions encountered during parts of the 2011 growing season likely slowed the degradation of some soil-residual herbicides, particularly those degraded by soil microorganisms,” said Hager. Dry soil conditions early in 2012 allowed for unusually early corn planting, which in some instances occurred before the end of the rotational interval of the herbicide used in 2011.

Hager said there have been several reports of corn injury that appear to be caused by fomesafen carryover. Veinal chlorosis or necrosis, which causes a striping effect on the leaves, is the most common of these symptoms.

“In some instances, the leaf veins almost appear clear or transparent, but the root system of affected plants usually shows no symptoms unless the foliar symptoms are extremely severe,” he explained.

Because of the fomesafen’s soil persistence and corn’s sensitivity to fomesafen residues, the labels of most products that contain it, including Flexstar, Flextar GT and Prefix, indicate a 10-month rotational interval for corn.

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 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
Wheat Growers, North Central Farmers Elevator Pursue Merger
CropLife 100Wheat Growers, North Central Farmers Elevator Pursue Merger
March 3, 2015
Two CropLife 100 retailers — South Dakota Wheat Growers (ranked No. 11) and North Central Farmers Elevator (No. 19) — have entered into a Letter of Intent to unify the two companies into a newly named cooperative. Read More
Growmark Group
CropLife 100GROWMARK In 2015: Back, To The Future
March 2, 2015
The nation’s third largest ag retail organization is simultaneously moving forward while remembering its past. Read More
CropLife 100Pinnacle Expands Sanders Brand In The South
February 27, 2015
Pinnacle has acquired Hopkins Seed and Chemical in Qulin, MO, which expands the company's Sanders brand to nine Southern states. Read More
CropLife 100Pinnacle Launches New Providence Agriculture Location In Indiana
February 27, 2015
Pinnacle Agriculture Holdings — ranked No. 6 on the CropLife 100 — has established a new retail location in New Castle, IN, which will operate as part of Pinnacle's Providence Agriculture brand. Read More
Carl Casale of CHS
CropLife 100Cooperative CHS Returns $518 Million To Owners
February 23, 2015
The 2015 cash return to owners is based on CHS net income of $1.1 billion, the company's second highest on record. Read More
Latest News
FungicidesSyngenta Suing Willowood Over Azoxystrobin Fungicide
March 27, 2015
Syngenta announced today that it has sued agrochemical maker Willowood, LLC., for patent and copyright infringement, as well as unfair Read More
ManagementRetail Week: The Future Of Mycogen Seeds; The 4Rs At Na…
March 27, 2015
Editors Eric Sfiligoj and Matt Hopkins discuss recent trips, including a look at the future of Mycogen Seeds at Dow Read More
Eric SfiligojMonsanto Hears The WHO
March 27, 2015
Another challenge to the safety of glyphosate, and the responses from supporters and opponents, calls to mind a classic Dr. Seuss story. Read More
Industry NewsMonty’s Plant Food Expands Sales Team
March 27, 2015
Monty’s Plant Food Company, a leader in natural soil enhancement and  plant fertility products, has hired Andrew Bullock as a Read More
Crop InputsSyngenta Louisiana Plant Poised For 2015 Production
March 26, 2015
As the 2015 planting season gets underway, growers across the country will need crop protection products to combat pests and Read More
Lake Erie Nutrient Stewardship
LegislationOhio Lawmakers Finalize Phosphorus Restrictions
March 25, 2015
State lawmakers on Wednesday finalized new rules designed to curb toxic algal blooms on Lake Erie, calling the regulations a major step forward in addressing the problem. Read More
Spreaders17 Fertilizer Spreaders For 2015
March 25, 2015
Manufacturers shoot for versatility and accuracy in this year's crop of fertilizer spreaders. Read More
Industry NewsMonty’s Hires Mid-South Product Consultant
March 25, 2015
Monty's Plant Food Co. has hired Matt Woodring as a Product Consultant for portions of Central Kentucky and Tennessee.    Read More
StewardshipMapShots Integrates With DriftWatch
March 23, 2015
Growers and agricultural providers using AgStudio FARM and AgStudio PRO can now view vital information about specialty crops and apiaries through a recent integration with the DriftWatch Specialty Crop Site Registry from FieldWatch, Inc. Read More
Crop InputsWorld Health Organization Report Contradicts Scientific…
March 23, 2015
A new report from the World Health Organization has classified glyphosate with a “2A” rating as a probable carcinogen, a Read More
Eric SfiligojSeed Treatment Stays Necessary
March 20, 2015
Grower-customers looking to scale back spending in 2015 won’t consider seed treatment, say experts. Read More
HerbicidesMARCH MADNESS: Industry Rallies Around Glyphosate Safet…
March 20, 2015
A newly published report from the International Agency for Research on Cancer (IARC) classifies the herbicide glyphosate as a "2A-rated possible carcinogen" and the ag industry responds by circling the wagons. Read More
ManagementRetail Week: Precision survey, a technology acquisition…
March 20, 2015
Editors Paul Schrimpf and Eric Sflilgoj discuss recent travel, the upcoming precision adoption survey, and an unusual sighting at a 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
Crop InputsBioSafe Launching TerraGrow Soil Inoculant
March 20, 2015
TerraGrow is a blend of beneficial bacterial and fungal spores and nutrients carefully designed to promote healthier soil and crops. Read More
Winter Wheat
AdjuvantsMax Systems Debuts New Adjuvant NanoRevolution 2.0
March 18, 2015
Added to a tank mix of glyphosate at the conservative rate of two to four ounces per acre, NanoRevolution 2.0 has proven effective in killing resistant weed species that had already had up to two applications of the leading glyphosate product. Read More
Photo credit: United Soybean Board/the Soybean Checkoff
Seed/BiotechAgnition Launches Microbial Catalyst Seed Treatment
March 18, 2015
Agnition it has launched Commence for Soybeans, a microbial catalyst seed treatment for soybeans that stimulates microbial activity for healthier soil and a superior growth environment. Read More
4R Certified, Nutrient Stewardship Council,
StewardshipTyler Grain & Fertilizer Now 4R Certified
March 18, 2015
The 4R Nutrient Stewardship Certification Program has announced Tyler Grain & Fertilizer Co. in Smithville, OH, has been added to Read More