Skip to Main Content
 

Herbicide Carryover Risk Following Dry Conditions

Categories: PLANTING, CORN, SOYBEANS
Share:
  • Herbicide carryover injury is not a large concern in most years, but it does have the potential to impact a field’s next crop following certain environmental conditions.

  • Potential risk is variable from field to field and even within each field.

  • Nutrient deficiencies can sometimes be mistaken for herbicide carryover.

What is Herbicide Carryover?

Herbicide carryover occurs when an active ingredient or metabolites of a herbicide applied the previous crop year remain in the soil at high enough concentrations to cause damage to sensitive crops the following season. Under typical conditions, herbicide rotational planting intervals defined on pesticide labels provide a reasonable amount of time to reduce potential injury, if followed accordingly.

Herbicide carryover matches spray boom width from previous year.
Figure 1. Herbicide carryover matching spray boom width from prior year where boom was charged

Herbicide labels often specify certain geographies, rates, application timing and soil type restrictions. Recommendations can change if specific restrictions are present at time of application. Under extreme conditions, some herbicides may be at risk of showing some crop response (Figure 1). Several factors can contribute to the risk of herbicide carryover:

  • Herbicide rate

  • Persistence of the herbicide

  • Soil characteristics

  • Annual precipitation and temperature

  • Interval time between herbicide application and planting the next crop

  • Susceptibility of the crop to the herbicide

  • Early-season crop growth rate1

Fate of Herbicides in Soil

Understanding what happens to a herbicide after reaching the soil is important in determining if it will persist and potentially carry over into the next crop. 1 of 3 things typically happen after herbicides are applied:

  1. Herbicides are removed from the soil.
    Herbicides can be carried away with surface water or leached through the soil profile. A portion of some herbicides may volatilize from the soil surface if not incorporated. Lastly, a portion of herbicides applied will be taken up and metabolized by plant leaves and roots.

  2. Herbicides adsorb to the soil.
    Herbicides can also bind to the surface of soil colloids (small particles) and organic matter.

  3. Herbicides degrade.
    Soil microbes, sunlight and chemical reactions will often begin to break herbicides down into an inactive form within the soil.

Types of Herbicide Degradation

Microbial degradation

Soil organisms known as microbes are largely responsible for naturally degrading herbicides in the soil over time. Specific forms of fungi, bacteria and algae commonly use herbicides as a source of food. Environmental conditions that promote microbial development are less likely to experience herbicide carryover. Higher microbial activity often observed in high organic matter soils also helps promote faster breakdown of herbicides. Microbial activity tends to decrease with extended periods of dry conditions, making droughty soils more prone to herbicide carryover. Microbe activity also tends to decrease with colder soil conditions which can be a factor in herbicide degradation in cooler environments.

Chemical degradation

A process in which some very specific herbicides react with soil water in a process called hydrolysis. This form of degradation needs water present to occur. Dry soil conditions reduce degradation activity in general.2 Chemical degradation can decrease in high pH and cooler soils.

Photodecomposition

This can occur with a very limited number of herbicides, such as Treflan™, when not incorporated into the soil. Sunlight will break down the molecules of these specific herbicides and make them inactive if left exposed on the soil surface for periods of time.

Considerations for Carryover Risk

Several factors act together to influence carryover risk. Potential risk can even vary within fields.

  1. Herbicide characteristics influence persistence:

    • Herbicide interactions in the soil are complex. Characteristics of herbicide active ingredients along with how they interact with the soil and environment determine how much is left at the time of the next crop planting.

    • The chemical structure of the herbicide impacts water solubility, vulnerability to degradation (microbial and chemical), soil binding and vapor pressure.

  2. Application factors:

    • Timing: Applying herbicides late in the season decreases the amount of time available for herbicide degradation.3 Rotational restrictions may not be met if applications are made late in the season.

    • Rate: Higher rates than what is on the label for soil characteristics or the geographical area may lead to injury of rotational crops the following year.

    • Application uniformity: Sprayer overlap can lead to areas receiving 2 times the herbicide rate, common on turn point rows or at the end of a sprayer pass. Sprayer malfunctions can also lead to application rates exceeding safe levels.

  3. Weather conditions:

    • Temperature impacts chemical processes and microbial activity. Warm temperatures favor herbicide degradation by both mechanisms.

    • Rainfall and moist soil conditions favor microbial activity, which increases degradation. Extended dry periods following application greatly reduce degradation, increasing persistence and risk of carryover.

  4. Soil characteristics:

    • Soil pH plays a role in the persistence of herbicides in the soil since it can influence microbial activity, chemical degradation and herbicide solubility.

    • Soil texture has an influence on herbicide persistence based on binding potential of the soil colloids. For example, clay and high organic matter soils bind herbicide molecules tightly to the surface, reducing the availability of the molecules to degradation.

  5. Crop rotation:

    • Crops differ in sensitivity to different herbicides, making some more sensitive to specific herbicides if there is any risk of carryover.

Reducing Risk of Herbicide Carryover

When planning for the next crop season, there are several things that can be done to reduce potential crop injury.

  1. Review records and labels: Understand which herbicides were applied the previous year and check each product’s labels for any restrictions and rotational intervals to other crops. Labels may list specific conditions, such as seasonal precipitation totals, which may limit some crops from being planted.

    • Herbicide carryover is rarely seen when pesticide labels are reviewed and followed.

  2. Avoid early planting: Herbicides taken up by plants in periods of cold stress can often cause higher levels of injury due to a reduced ability to metabolize herbicides. Delaying planting until warmer conditions promotes rapid growth, helping better tolerate herbicide applications.

  3. Switch crops: Rotating to a less sensitive crop may need to be considered based on risk of carryover.

  4. Consider tillage: Tillage can distribute herbicides evenly throughout the soil often helping dilute herbicide concentrations and helping encourage microbial activity.

  5. Soil testing: Soil testing can be done to measure residue, but it is generally quite expensive and requires a very representative soil sample to have any true value.

Symptoms Confused with Herbicide Carryover

Leaf striping in this plant occurs from sulfur deficiency, which can mimic herbicide carryover injury.
Figure 2. Leaf striping from sulfur deficiency that appears similar to herbicide carryover injury

Herbicide carryover injury is generally difficult to diagnose. Often, carryover injury appears in uniform patterns where herbicide application overlap occurred. Soil type, high or low spots and weather conditions after herbicide application are key factors in potential crop injury symptoms.

Symptoms such as abnormal leaf or growing point development and chlorosis or necrosis of leaves can result from causes other than herbicide carryover injury. Many symptoms, such as disease, nutrient imbalance, frost, excessive moisture, heat stress or drought, can mimic herbicide carryover symptoms (Figure 2). Symptoms observed in early vegetative stages can often disappear quickly with new growth and have little, if any, effect on overall yield potential. A detailed analysis of all cropping information, as well as careful examination of the above- and below-ground symptoms, should be considered when determining the cause of an unhealthy crop.

There is little that can be done to change the amount of herbicide present in the soil at planting, but several options may help reduce injury risk. When herbicides are applied properly under typical growing conditions, there will be little concern of herbicide carryover risk. However, use caution following herbicide applications when conditions are conducive for herbicide persistence, such as a long-term drought.

References

Hartzler, B. 2020. Herbicide carryover concerns for 2020. Iowa State University Extension and Outreach.
https://crops.extension.iastate.edu/blog/bob-hartzler/herbicide-carryover-concerns-2020
Ikley, J. and B. Johnson. 2018. Factors affecting herbicide carryover in 2018. Purdue University. Extension Entomology. Pest & Crop Newsletter.
https://extension.entm.purdue.edu/newsletters/pestandcrop/article/factors-affecting-herbicide-carryover-in-2018/
3 Sprague, C. 2012. Dry conditions will likely impact herbicide carryover to rotational crops. Michigan State University Extension.
https://www.canr.msu.edu/news/dry_conditions_will_likely_impact_herbicide_carryover_to_rotational_crops

All photos are either the property of Syngenta or used with permission

Syngenta hereby disclaims any liability for Third Party websites referenced herein.

Performance assessments are based upon results or analysis of public information, field observations and/or internal Syngenta evaluations.

Product performance assumes disease presence.

© 2022 Syngenta. Important: Always read and follow label instructions. Some products may not be registered for sale or use in all states or counties. Please check with your local extension service to ensure registration status. AAtrex 4L, AAtrex Nine-O, Acuron, Agri-Flex, Agri-Mek 0.15EC, Agri-Mek SC, Avicta 500FS, Avicta Complete Beans 500, Avicta Complete Corn 250, Avicta Duo Corn, Avicta Duo 250 Corn, Avicta Duo COT202, Avicta Duo Cotton, Besiege, Bicep II Magnum, Bicep II Magnum FC, Bicep Lite II Magnum, Callisto Xtra, Cyclone SL 2.0, Denim, Endigo ZC, Endigo ZCX, Epi-Mek 0.15EC, Expert, Force, Force 3G, Force CS, Force 6.5G, Force Evo, Gramoxone SL, Gramoxone SL 2.0, Gramoxone SL 3.0, Karate, Karate with Zeon Technology, Lamcap, Lamcap II, Lamdec, Lexar EZ, Lumax EZ, Medal II ATZ, Minecto Pro, Proclaim, Tavium Plus VaporGrip Technology, Voliam Xpress and Warrior II with Zeon Technology are Restricted Use Pesticides.

Some seed treatment offers are separately registered products applied to the seed as a combined slurry. Always read individual product labels and treater instructions before combining and applying component products.

Orondis Gold may be sold as a formulated premix or as a combination of separately registered products: Orondis Gold 200 and Orondis Gold.

Important: Always read and follow label and bag tag instructions; only those labeled as tolerant to glufosinate may be sprayed with glufosinate ammonium-based herbicides. LibertyLink®, Liberty® and the Water Droplet logo are registered trademarks of BASF. HERCULEX® and the HERCULEX Shield are trademarks of Corteva Agriscience LLC. HERCULEX Insect Protection technology by Corteva Agriscience LLC. Under federal and local laws, only dicamba-containing herbicides registered for use on dicamba-tolerant varieties may be applied. See product labels for details and tank mix partners. Golden Harvest® and NK® soybean varieties are protected under granted or pending U.S. variety patents and other intellectual property rights, regardless of the trait(s) within the seed. The Enlist E3® soybean, LibertyLink®, LibertyLink® GT27®, Roundup Ready 2 Xtend®, Roundup Ready 2 Yield® and XtendFlex® soybean traits may be protected under numerous United States patents. It is unlawful to save soybeans containing these traits for planting or transfer to others for use as a planting seed. Only dicamba formulations that employ VaporGrip® Technology are approved for use with Roundup Ready 2 Xtend® and XtendFlex® soybeans. Only 2,4-D choline formulations with Colex-D® Technology are approved for use with Enlist E3® soybeans. The trademarks or service marks displayed or otherwise used herein are the property of a Syngenta Group Company. ENLIST E3® soybean technology is jointly developed with Corteva Agriscience LLC and M.S. Technologies, L.L.C. The ENLIST trait and ENLIST Weed Control System are technologies owned and developed by Corteva Agriscience LLC. ENLIST® and ENLIST E3® are trademarks of Corteva Agriscience LLC. GT27® is a trademark of M.S. Technologies, L.L.C. and BASF. Roundup Ready 2 Xtend®, Roundup Ready 2 Yield®, XtendFlex®, VaporGrip® and YieldGard VT Pro® are registered trademarks used under license from the Bayer Group.

All other trademarks are the property of their respective owners. More information about Agrisure Duracade® is available at http://www.biotradestatus.com/.


Contact a local seed advisor

X

You are viewing from

Thank you for visiting the Golden Harvest website. We understand how important it is for you to find agronomic and product information pertinent to your local area. Please enter your zip code or select your area below to ensure you are seeing the information that matters most to you.
Learn more about regions >

CHANGE BY ZIP CODE OR SELECT YOUR REGION

OR
We’re sorry. Golden Harvest is not available in this area. Please try another zip code or contact a Golden Harvest Seed Advisor for more information.

Is this page helpful to you?

How can we improve
this page? (optional)

Can you tell us your
role in agriculture? (optional)

Thanks for the feedback.

We appreciate your participation