Precautions With Late-Season Herbicide Applications

The adverse environmental conditions common across much of Illinois are challenging the performance of many foliar-applied soybean herbicides.

Weeds that survive an initial herbicide application are often resprayed later in the season. However, according to University of Illinois associate professor of weed science Aaron Hager, the likelihood of controlling larger, moisture-stressed weeds continues to decline.

Moreover, herbicides applied late in the season are more likely to persist long enough to injure sensitive rotational crops. Nearly all herbicide labels (soil-applied or postemergence) specify the interval between herbicide application and planting a rotational crop. Some of these restrictions are based solely on time, while others take into account factors such as soil pH and the amount of precipitation received after herbicide application when determining interval length.

“Soil moisture is often the most critical factor governing the efficacy and persistence of soil-residual herbicides,” Hager said. “Many herbicides are degraded in soil by the activity of soil microorganisms, and populations of these microorganisms can be greatly depressed when soil moisture is limited.”

Dry soils can also enhance herbicide adsorption to soil colloids, thus rendering the herbicide unavailable for plant uptake and degradation by soil microbial populations. Some herbicide rotational intervals are increased if a specified amount of precipitation is not received by a certain calendar date.

The intervals are established to prevent herbicide residues from reaching levels that will adversely affect the rotational crop. Respecting these intervals becomes particularly important with late-season herbicide applications and when soil moisture is limited.

“Please keep in mind that the labels of almost all postemergence soybean herbicides indicate a preharvest interval or a soybean developmental stage beyond which applications cannot be made,” said Hager.

Labels of some products may indicate both a developmental stage (before soybean bloom, for example) and a preharvest interval. Preharvest intervals indicate the amount of time that must elapse between the herbicide application and crop harvest.

Failure to observe the preharvest interval may result in herbicide residue levels in the harvested portion of the crop in excess of established limits. Moreover, labels on many postemergence soybean herbicides specify that foraging of, or grazing livestock on, treated soybean is not allowed.

Leave a Reply

Herbicides Stories

glyphosate
Crop InputsWHO: Glyphosate ‘Unlikely’ To Cause Cancer
May 16, 2016
Via Reuters.com reporter Kate Kelland: The weed-killing pesticide glyphosate, made by Monsanto and widely used in agriculture and by gardeners, Read More
dicamba, Roundup Ready 2 Xtend
Crop InputsASA: No Dicamba On Roundup Ready 2 Xtend In 2016
May 16, 2016
While Roundup Ready 2 Xtend (RR2X) are tolerant to dicamba and glyphosate herbicides, no dicamba herbicides will be approved for Read More
CPP, glyphosate, dicamba, atrazine,
Crop InputsReport: Congress Pressing EPA On Glyphosate Review Handling
May 16, 2016
Via Reuters.com reporter P.J. Huffstutter: U.S. lawmakers have asked EPA to explain why it published – and then withdrew – Read More
Palmer amaranth in soybean stubble
HerbicidesWSSA: Billions In Potential Economic Losses From Uncontrolled Weeds
May 4, 2016
What losses would corn and soybean growers experience if they were forced to eliminate herbicides and other control techniques from Read More
Trending Articles
Monsanto Luling Plant
Crop InputsReport: Bayer Eyeing Monsanto For Possible Mega-Merger
May 16, 2016
Bayer AG is exploring a potential bid for U.S. competitor Monsanto Co. in a deal that would create the world’s Read More
Aerial Drone
Precision AgA Deeper Dive Into The Future Of Precision Ag
May 9, 2016
For about two decades now, through the good and the bad times, the ups and the downs inherent in agriculture, Read More
Palmer amaranth in soybean stubble
HerbicidesWSSA: Billions In Potential Economic Losses From Uncontrolled Weeds
May 4, 2016
What losses would corn and soybean growers experience if they were forced to eliminate herbicides and other control techniques from Read More
Eric SfiligojReasons For Hope In Commodity Prices
May 2, 2016
For many months now, the doomsayers have ruled the day in agriculture. Too much supply with too little demand would Read More
Eric SfiligojMissing The Family Ties In Agriculture
April 25, 2016
By its nature, the agriculture market is cyclical. Up and down cycles come and go with a regular pattern. For Read More
HerbicidesHerbicide Resistance In Waterhemp Continues To Grow
April 22, 2016
Twenty-five years ago, waterhemp was virtually unknown to Illinois farmers. Today, the broadleaf weed blankets corn and soybean fields across Read More
Latest News
Southern States Cooperative
Corn Field
Industry NewsTiger-Sul Names Veteran Account Manager To Lead Central…
May 23, 2016
With the continuing growth of the sulphur bentonite and precision crop nutrient industry, global agriculture firm H.J. Baker has announced that Read More
Bayer sign
Industry NewsReuters: Bayer Defies Critics With $62 Billion Monsanto…
May 23, 2016
German drugs and crop chemicals group Bayer has offered to buy U.S. seeds company Monsanto for $62 billion in cash, Read More
Eric SfiligojPity The Monsanto Haters
May 23, 2016
An old saying goes thus: “Be careful what you wish for. You just might get it.” Given current events, there Read More
Industry NewsCompass Minerals Hires Industry Veteran To Lead Plant N…
May 19, 2016
Compass Minerals has hired plant nutrition industry veteran Vatren Jurin to steer the company’s portfolio expansion into specialty liquid micronutrient Read More
ASMARK Retailers LIVE! Tour 2016 Group shot The Andersons
CropLife 100The Andersons Rejects Unsolicited Proposal From HC2
May 19, 2016
The Andersons, Inc. has announced that its Board of Directors has rejected two non-binding, highly conditional, unsolicited proposals from HC2 Read More
glyphosate
Crop InputsWHO: Glyphosate ‘Unlikely’ To Cause Cancer
May 16, 2016
Via Reuters.com reporter Kate Kelland: The weed-killing pesticide glyphosate, made by Monsanto and widely used in agriculture and by gardeners, Read More
dicamba, Roundup Ready 2 Xtend
Crop InputsASA: No Dicamba On Roundup Ready 2 Xtend In 2016
May 16, 2016
While Roundup Ready 2 Xtend (RR2X) are tolerant to dicamba and glyphosate herbicides, no dicamba herbicides will be approved for Read More
CPP, glyphosate, dicamba, atrazine,
Crop InputsReport: Congress Pressing EPA On Glyphosate Review Hand…
May 16, 2016
Via Reuters.com reporter P.J. Huffstutter: U.S. lawmakers have asked EPA to explain why it published – and then withdrew – Read More
Monsanto Luling Plant
Crop InputsReport: Bayer Eyeing Monsanto For Possible Mega-Merger
May 16, 2016
Bayer AG is exploring a potential bid for U.S. competitor Monsanto Co. in a deal that would create the world’s Read More
ManagementAsmark Institute Tour Observations
May 12, 2016
Special Guest CropLife Field Editor Matthew Grassi discusses his week-long visit with 45 ag retailers as part of the Asmark Read More
MicronutrientsCompass Minerals Expands Trial Work For Wolf Trax Innov…
May 12, 2016
Fertilizer manufacturer Compass Minerals continues to expand the evaluation program for its Wolf Trax micronutrient fertilizer products, according to a Read More
Young Corn Closeup
Industry NewsArysta Adds To Marketing Team
May 12, 2016
Arysta LifeScience North America recently announced the addition of David Davies to its marketing team. As marketing manager, Davies will Read More
Photo credit: The United Soybean Board/The Soybean Checkoff.
Crop InputsSyngenta Launches New Biological Seed Treatment
May 12, 2016
Syngenta has announced the launch of the EPIVIO brand family, a range of new biostimulants which address abiotic stresses through seed Read More
Crop Inputs2013 West Texas Tragedy Ruled A ‘Criminal ActR…
May 11, 2016
A 2013 fertilizer plant blast in West, TX, that killed 15 people and injured 160 others was caused by a Read More
Crop InputsLariat Partners Invests In Willowood USA
May 11, 2016
Lariat Partners, a Denver-based private equity firm, has made a significant investment in Willowood USA, a leading manufacturer of generic Read More
Anhydrous Ammonia tanks
LegislationARA: OSHA Announces PSM Formal Rulemaking Intentions
May 11, 2016
In separate communications earlier this week, the Occupational Safety and Health Administration (OSHA) announced plans to conduct formal rulemaking to Read More
The Andersons Fostoria
StewardshipThe Andersons Facilities In Fostoria And Gibsonburg, OH…
May 11, 2016
The 4R Nutrient Stewardship Certification Program has announced that The Andersons, Inc.’s facilities in Fostoria and Gibsonburg, OH, have been added to its Read More