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

Crop InputsBASF: In Arkansas Drift Cases, Buffer Zones Mostly Not Followed
July 24, 2017
BASF on Thursday addressed questions about spreading dicamba drift issues on a media briefing call. In Arkansas – which is Read More
Tim Hassinger Dow AgroSciences President and CEO
Crop InputsDow’s Tim Hassinger Named President, CEO of Lindsay Corp.
July 24, 2017
Lindsay Corp. has  announced the appointment of Timothy Hassinger as president and CEO and a member of its board of Read More
Soil soybean closeup
FertilizerThe 4Rs and Potassium
July 17, 2017
Are we meeting crop K needs? Using the 4R nutrient stewardship approach of selecting the right source at the right Read More
Soybean Field Sunset
Crop InputsWhich is Better for Soybeans: Fall or Spring Applications?
July 17, 2017
There have been many questions about fall versus spring applications of phosphorus (P) and potassium (K) to soybeans, writes Dr. T. Read More
Trending Articles
Stewardship‘Gonna Fly Now’ with Environmental Respect
July 20, 2017
One of the most memorable moments in movie history occurred in the Academy Award-winning 1976 film “Rocky.” Haven gotten his Read More
StewardshipEnvironmental Respect 2017 Kicks Off Enjoying an American Pastime
July 18, 2017
Following months of planning and scheduling, the 2017 Environmental Respect Awards (ERA) celebration kicked off in fine fashion as more Read More
Soybean Closeup
Crop InputsMissouri Lifts Dicamba Ban, Issues Stricter Application Parameters
July 14, 2017
The Missouri Department of Agriculture has lifted its barely week-old ban on new dicamba technologies, which have been at the Read More
Crop InputsMonsanto Responds to Arkansas, Missouri Dicamba Bans
July 10, 2017
Monsanto, provider of the dicamba-tolerant Roundup Ready Xtend crop system for soybeans and cotton, issued the following statement on Friday, Read More
Retail FacilitiesPCS-Hammond Meets Fertilizer Storage Needs with New Dome Facility
July 8, 2017
The new barrel dome facility at the PCS-Hammond Regional Distribution Center in Hammond, IN, can hold more than 100,000 tons Read More
PrecisionAg Vision Conference
Precision AgPrecisionAg® Vision Conference: Focused on the Future
June 13, 2017
PrecisionAg® is pleased to announce the return of its PrecisionAg Vision Conference, October 10-12, 2017. Based on overwhelmingly positive response Read More
Latest News
Crop InputsBASF: In Arkansas Drift Cases, Buffer Zones Mostly Not …
July 24, 2017
BASF on Thursday addressed questions about spreading dicamba drift issues on a media briefing call. In Arkansas – which is Read More
Tim Hassinger Dow AgroSciences President and CEO
Crop InputsDow’s Tim Hassinger Named President, CEO of Linds…
July 24, 2017
Lindsay Corp. has  announced the appointment of Timothy Hassinger as president and CEO and a member of its board of Read More
Eric SfiligojThe 2017 Ambassadors of Respect Come from Around the Gl…
July 24, 2017
After a week of fun, enjoying food, sights, and company information, DuPont Crop Protection representatives and their Environmental Respect guests Read More
ManagementCropLife Retail Week: Dicamba Update and InfoAg Preview
July 21, 2017
Editors Eric Sfiligoj and Paul Schrimpf discuss reports from the field and comments from Monsanto about dicamba drift this season, Read More
Stewardship‘Gonna Fly Now’ with Environmental Respect
July 20, 2017
One of the most memorable moments in movie history occurred in the Academy Award-winning 1976 film “Rocky.” Haven gotten his Read More
StewardshipEnvironmental Respect: Grand Grounds, Posters Parade
July 19, 2017
To celebrate their accomplishments in the area of environmental stewardship, award recipients at the 2017 Environmental Respect week spent much Read More
StewardshipHarden’s Message to ERA Winners: Do Tell Your Good Stor…
July 19, 2017
As the daughter of a peanut farmer, Krysta Harden, Chief Sustainability Officer for DuPont Crop Protection, understands the importance the Read More
StewardshipFarming Smarter Hinges on 4R Best Management Practices
July 18, 2017
Preserving water quality while feeding another 2 billion people by 2050 is the challenge facing North America’s farmers and its Read More
StewardshipEnvironmental Respect 2017 Kicks Off Enjoying an Americ…
July 18, 2017
Following months of planning and scheduling, the 2017 Environmental Respect Awards (ERA) celebration kicked off in fine fashion as more Read More
Soybean Field Sunset
OpinionPicking Partners in the Crop Protection Market
July 17, 2017
Agriculture is a market awash in highs, lows, and everything in between. This is certainly true in the world of Read More
TMX-2050-In-Cab-Display-Launch-Run-Screen
EquipmentGPS Auto Steer: Innovating in a Mature Market
July 17, 2017
In the world of Big IRON, GPS auto steer has closely mirrored the evolutionary path of consumer GPS Navigation systems Read More
MFA-Centralia-MO
Eric SfiligojThe Resilience of Ag Retailers
July 17, 2017
After covering the ag retail market for 17 years, I think one of the most impressive character traits I’ve seen Read More
SERA-meeting
Stewardship4R Event Explores How to Minimize Phosphorus Losses
July 17, 2017
This year the Southern Extension and Research Activity (SERA) – 17; will be meeting in Oregon, OH, from August 14-17. Read More
Students Soybean Field
StewardshipCCA 4R Study Guide Available
July 17, 2017
In June the International Plant Nutrition Institute (IPNI) released the Certified Crop Advisor (CCA) 4R Nutrient Management Specialist (4R NMS) Read More
Soil soybean closeup
FertilizerThe 4Rs and Potassium
July 17, 2017
Are we meeting crop K needs? Using the 4R nutrient stewardship approach of selecting the right source at the right Read More
Soil Young Corn
StewardshipTop 10 Themes from the 2017 4R Nutrient Stewardship Sum…
July 17, 2017
Preserving water quality while feeding another 2 billion people by 2050 is the challenge facing North America’s farmers and its Read More
Soybean Field Sunset
Crop InputsWhich is Better for Soybeans: Fall or Spring Applicatio…
July 17, 2017
There have been many questions about fall versus spring applications of phosphorus (P) and potassium (K) to soybeans, writes Dr. T. Read More
corn-potassium-deficiency-University-of-Minnesota-Extension
Crop InputsRecognizing Potassium Deficiency Symptoms in Crops
July 17, 2017
Some crops exhibit characteristic deficiency symptoms when adequate amounts of K are not available for growth and development, according to Read More