Soybean Injury From Soil-Applied Herbicides

Integrated weed management programs offer the greatest potential for long-term, sustainable solutions to weed populations demonstrating resistance to herbicides from multiple families. Soil-residual herbicides are important components of integrated weed management programs and provide several benefits, including reducing the intensity of selection for resistance to foliar-applied herbicides. Recent survey data indicate the percentage of Illinois soybean acres treated with soil-residual herbicides has increased during the past few years, according to weed scientist Aaron Hager, University of Illinois.

In the vast majority of instances, soil-applied herbicides control target weed species with little to no adverse effect on the crop. However, soybean plants sometimes are injured by these herbicides. Questions about soybean injury caused by soil-applied herbicides recently have been posed, so this article will review some of the factors that can contribute to herbicide-induced soybean injury.

Herbicides vary in their inherent potential to cause soybean injury. Many university-generated herbicide effectiveness rating tables also provide estimates of soybean injury potential. Some herbicide active ingredients, such as cloransulam and clomazone, are often rated as having very low potential to cause soybean injury, whereas other active ingredients are rated as having a greater inherent potential to cause injury. The rate at which the herbicide is applied can influence the potential for soybean injury by increasing or decreasing the amount of herbicide in a given volume of soil.

Most many cultivars are not overly sensitive to any particular herbicide, but other soybean cultivars can vary in their sensitivity to certain herbicides. Data in the scientific literature and company-generated variety trials demonstrate cultivar sensitivity differences to various soil-residual herbicides. Some cultivars demonstrate sensitivity to one active ingredient, whereas other cultivars can be sensitive to more than one active ingredient.

The environment has a large influence on the severity of soybean injury caused by soil-applied herbicides. Environment-induced crop stress, often caused by cool, wet soil conditions, can enhance soybean injury from soil-applied herbicides. In most cases, herbicide selectivity arises from the soybean plant’s ability to rapidly metabolize the herbicide to a nonphytotoxic form before it causes much visible injury. Soybean plants growing under favorable conditions are able to adequately metabolize the herbicide before any injury symptoms are expressed. However, when the soybean plant is under stress, its ability to metabolize the herbicide can be sufficiently reduced to the point at which injury symptoms develop.

Soil physical properties can increase or decrease the potential for soybean injury by impacting how much herbicide is available for plant uptake. Soils with higher amounts of clay and organic matter have a greater ability to adsorb more herbicide onto these soil colloids. Herbicide bound to soil colloids is not available for plant uptake. In contrast, coarse-textured soils have less adsorptive capacity so more herbicide remains available for plant uptake. Labels of soil-applied herbicides often contain precautionary language about the increased potential for soybean injury when the product is applied to sandy soils or soils low in organic matter.

The application timing of soil-residual herbicides also can impact the potential for soybean injury. Applications made immediately before or after soybean planting result in a high concentration of herbicide near the emerging soybean plants. In contrast, a herbicide is often more widely distributed within the soil profile by the time of soybean emergence when applications are made several days or weeks prior to planting.

The soil-applied PPO-inhibiting herbicides, including saflufenacil, flumioxazin and sulfentrazone, are very effective for control of Amaranthus species. These herbicides (and many others) also can cause soybean injury.

“Our first experience with soybean injury from soil-applied PPO inhibitors occurred in 1996 while evaluating sulfentrazone for control of herbicide-resistant waterhemp,” Hager said. “Soybean injury symptoms caused by these soil-applied herbicides can vary depending on the soybean developmental stage when exposure occurred.”

The most commonly encountered injury symptoms occur on the hypocotyl and cotyledons, often indicating the plants were exposed to a high concentration of herbicide as they were emerging.

 

Injury symptoms caused by soil-applied herbicides evident on emerging soybean plant. Photo credit: Aaron Hager, University of Illinois
Injury symptoms caused by soil-applied herbicides evident on emerging soybean plant. Photo credit: Aaron Hager, University of Illinois

Symptoms include necrotic lesions on the soybean hypocotyl near the soil surface and reddish-colored spots or lesions on the hypocotyl and/or cotyledons. Lesions on the hypocotyl may not always kill the young soybean plants, but can create an area of weakened tissue that may lead to stems breaking during rain or high wind. In severe cases, plants may actually die following emergence of the cotyledons.

Other symptoms can occur after soybean emergence if treated soil is splashed into the soybean meristem by heavy precipitation.

“There likely is no solitary reason for the recent instances of soybean injury from soil-applied PPO-inhibiting herbicides,” Hager said. “As previously mentioned, our first experience with this type of soybean injury occurred almost 20 years ago and we have continued to observe this type of injury intermittently ever since.”

These herbicides have become very popular choices for the management of herbicide-resistant Amaranthus populations, and widespread application of these herbicides increases the probability of encountering soybean cultivars that inherently are more sensitive to one or more of these herbicides.

In many instances of soybean injury, the herbicide was applied after soybean fields were planted and a precipitation event occurred within a few days of soybean emergence. Cool air and soil temperatures during the same interval can further increase injury potential by slowing the rate of herbicide metabolism. A crusted soil surface can slow soybean emergence, increasing the time the hypocotyl and cotyledons remain in the zone of high herbicide concentration. Once the herbicide is moved deeper into the soil profile, the potential to cause additional injury is greatly reduced.

Topics:

Leave a Reply

Crop Inputs Stories

Soybean Field
FungicidesSyngenta Launches Interactive Tools For Vibrance Seed Treatment Fungicide
August 30, 2016
As part of the ongoing commitment to provide growers and retailers with the most current crop protection products and agronomic Read More
Crop InputsDuPont Pioneer: Corn Belt P and K Levels Lagging
August 24, 2016
A new DuPont Pioneer study conducted across 12 Corn Belt states demonstrates that growers may be leaving profit potential in Read More
Monsanto sign
Crop InputsCould a Monsanto-Bayer Union Be 2 Weeks from Fruition?
August 24, 2016
Via STLToday.com (The St. Louis Post-Dispatch): Merger talks between Monsanto Co. and Bayer AG are advancing after a series of Read More
Syngenta Sign
Crop InputsChemChina, Syngenta Receive Clearance From CFIUS
August 22, 2016
China National Chemical Corp. (ChemChina) and Syngenta have announced that the companies have received clearance on their proposed transaction from the Read More
Trending Articles
ASMARK 2016 Retailers Live! Tour - CPS
CropLife 100CPS Acquires Texas Retail Operation
August 23, 2016
Crop Production Services (CPS) has acquired the assets of Larry’s Chemical and Spray, Inc., for an undisclosed amount in an Read More
Key Cooperative Marcus Construction Steel Building
Retail FacilitiesMarcus Construction Builds High-Speed Agronomy Center For Key Cooperative
July 7, 2016
Key Cooperative in Grinnell, IA, wanted a state-of-the-art Agronomy Center to better serve its customers. Marcus Construction delivered exactly that. Read More
Heritage Cooperative
Retail FacilitiesKahler Automation Designs State-Of-The-Art Facility For Heritage Cooperative
July 4, 2016
Heritage Cooperative in Marysville, OH, needed an efficient liquid, dry and grain facility to serve the many needs of their Read More
The Andersons Waterloo
ManagementFirst Indiana Facility Certified Under 4R Nutrient Stewardship Certification Program
June 27, 2016
The 4R Nutrient Stewardship Certification Program has announced that The Andersons, Inc.’s Waterloo, IN, facility has been added to its Read More
Food IT
Industry NewsCalifornia Event Will Mix Ag And Tech Professionals To Explore IT Solutions
June 20, 2016
Silicon Valley is hot on agriculture, and an upcoming event in California will bring together the food and tech industries Read More
Monsanto Luling Plant
Eric SfiligojWhat’s Next For Monsanto?
May 31, 2016
For the folks at Monsanto’s headquarters in St. Louis, MO, it has been an eventful few weeks. Back on May Read More
Latest News
Soybean Field
FungicidesSyngenta Launches Interactive Tools For Vibrance Seed T…
August 30, 2016
As part of the ongoing commitment to provide growers and retailers with the most current crop protection products and agronomic Read More
EquipmentAGCO Celebrates Manufacturing In Minnesota
August 30, 2016
AGCO Corp. welcomed the I Make America campaign to its Jackson, MN, factory last Friday to celebrate the contributions of manufacturing Read More
MAGIE 2015 Overview
Eric SfiligojThe Read From MAGIE
August 29, 2016
As I write this column, I’ve just returned from the annual Midwest AG Industries Exposition (MAGIE) in Bloomington, IL. Being Read More
EquipmentAGCO Opens Nominations For 11th Annual Operator Of The …
August 29, 2016
AGCO Corp. is now accepting nominations for 2016 Operator of the Year, which recognizes hard-working applicators across the country. These Read More
CHS St. Paul, MN fertilizer terminal
CropLife 100CHS Completes $10 Million Renovation Of St. Paul Agrono…
August 29, 2016
CHS Inc., North America’s leading farmer-owned cooperative and a global energy, grains and foods company, has completed a $10 million Read More
2016 ShowStopper | Case IH Patriot 4440 Sprayer
Equipment5 Show-stopping Products On Display At 2016 MAGIE
August 26, 2016
For 10 years now, visitors to the yearly Midwest AG Industries Exposition (MAGIE) show have been tasked with voting for Read More
Crop InputsDuPont Pioneer: Corn Belt P and K Levels Lagging
August 24, 2016
A new DuPont Pioneer study conducted across 12 Corn Belt states demonstrates that growers may be leaving profit potential in Read More
Monsanto sign
Crop InputsCould a Monsanto-Bayer Union Be 2 Weeks from Fruition?
August 24, 2016
Via STLToday.com (The St. Louis Post-Dispatch): Merger talks between Monsanto Co. and Bayer AG are advancing after a series of Read More
EquipmentCase IH Debuts Nutri-Tiller 955 Strip-Till Applicator
August 24, 2016
With strip-till continuing to expand across new acres, Case IH designed the new Nutri-Tiller 955 strip-till applicator to help producers Read More
EquipmentCase Launches Aim Command FLEX, 25th Anniversary Patrio…
August 24, 2016
Case IH announces new AIM Command FLEX advanced spray technology for greater application accuracy, as well as special 25th Anniversary Read More
ASMARK 2016 Retailers Live! Tour - CPS
CropLife 100CPS Acquires Texas Retail Operation
August 23, 2016
Crop Production Services (CPS) has acquired the assets of Larry’s Chemical and Spray, Inc., for an undisclosed amount in an Read More
PrecisionAg Video Conference
Precision AgVideo: PrecisionAg Vision Conference
August 22, 2016
A Strategic Conference Focused on the Future of Farm Digitization and Precision Agriculture Visit precisionagvision.com and register today! Read More
Young Corn Plants
Industry NewsOABA Welcomes Nicole Wallace As Communication & Adm…
August 22, 2016
The Ohio AgriBusiness Association has hired Nicole Wallace as its communication and administrative coordinator. Wallace will help provide comprehensive communication Read More
Syngenta Sign
Crop InputsChemChina, Syngenta Receive Clearance From CFIUS
August 22, 2016
China National Chemical Corp. (ChemChina) and Syngenta have announced that the companies have received clearance on their proposed transaction from the Read More
ManagementAg Industry Shows and Rumors
August 18, 2016
Editors Paul Schrimpf and Eric Sfiligoj talk about the upcoming trade show schedule, crop protection merger updates, and content for Read More
MAGIE 2015
EquipmentMAGIE Takes The Pulse Of The Ag Retail Industry
August 18, 2016
Every year, one of the major highlights of my career as an ag journalist is attending the Midwest AG Industries Read More
MAGIE 2015 Overview
EquipmentPride In Professionalism On Display At MAGIE
August 18, 2016
The Illinois Fertilizer & Chemical Association (IFCA) is proud to partner with CropLife IRON and continue the tradition of bringing Read More
SprayersJenner Ag To Debut 25th Anniversary Edition Case IH Pat…
August 18, 2016
Visitors at the 2016 Midwest Ag Industries Exhibition (MAGIE) in Bloomington, IL, will have a unique photo opportunity, as Jenner Read More