Climate Change & Weed Management: Corn

How to use the tables:

First, locate the right table for the herbicide you’re using

Glyphosate (also known as RoundUp®) has its own table, while all other herbicides are in a separate table

For the “Other Herbicides” table, identify the brand/chemical you use based on the name and the group number

Then, see if the table has data for a weed species you’re trying to manage (e.g. Lambsquarters)

You can then see how the performance of the herbicide against the weed will change under different climate conditions.

  • A red “-“ means the herbicide will be less effective as the climate factor increases
  • A green “+” means the herbicide will be more effective as the climate factor increases
  • A blue “=” means there will be no change in efficacy
  • A white “ND” means there was no research data for that interaction
  • S and R refer to susceptible or resistant biotypes (e.g. "-R" means efficacy is reduced against resistant biotypes)

Glyphosate Efficacy in Corn

 

Photosynthetic pathwayCommon name
(Scientific name)
CO2TemperatureDroughtReference Number
C3​Velvetleaf
(Abutilon theophrasti)
ND​ND​16
C3​Common ragweed
(Ambriosia artemisiifolia)
+ (S+R) | – (R)ND​14​, 9, 8
C3​Giant ragweed
(Ambriosia trifida)
ND​+ND​9
C3​Common lambsquarters
(Chenopodium album)
ND​2, 10, 18
C3​Horseweed
(Conyza canadensis)
ND​10
C3​Quackgrass
(Elymus repens)
ND​ND​2, 4, 5
C4​Smooth pigweed
(Amaranthus hybridus)
ND​+ND​12
C4​Redroot pigweed
(Amaranthus retroflexus)
=ND​ND​18
C4​Yellow nutsedge
(Cyperus esculentus)
=ND​ND​7
C4​Purple nutsedge
(Cyperus rotundus)
=ND​ND​7

Other Herbicides Efficacy in Corn

 

Herbicide 
(Trade name)
Herbicide group numberPhotosynthetic pathwayCommon name 
(Scientific name)
CO2TemperatureReference number
2-4, D4C3Wild buckwheat 
(Polygonum convolvulus)
+ND16
Atrazine 
(Aatrex®)
5C3Velvetleaf 
(Abutilon theophrasti)
ND+4
Common ragweed 
(Ambriosia artemisiifolia)
ND+4
Barley 
(Hordeum vulgare)
ND+16
Bentazon 
(Basasgran®)
6C4Smooth pigweed 
(Amaranthus hybridus)
ND+12
Bromoxynil 
(Maestro®)
6C4Kochia 
(Kochia scoparia)
=ND16
Dicamba 
(Clarity®)
4C4Kochia
(Kochia scoparia)
ND4
Glufosinate 
(Liberty®)
10C4Smooth pigweed 
(Amaranthus hybridus)
ND+12
Halosulfuron 
(Permit®)
2C4Yellow nutsedge 
(Cyperus esculentus)
=ND7
Purple nutsedge 
(Cyperus rotundus)
=ND7
Linuron 
(Lorox®)
5C3Wild buckwheat
(Polygonum convolvulus)
ND4
5C4Smooth pigweed 
(Amaranthus hybridus)
ND+12
Mesotrione 
(Callisto®)
27C4Palmer amaranth 
(Amaranthus palmeri)
ND4
Metolachlor 
(Dual Magnum®)
15C4Smooth pigweed 
(Amaranthus hybridus)
ND+11

Management Recommendations

Credit to Vipan Kumar, Associate Professor at Cornell School of Integrative Plant Science Soil and Crop Sciences Section, and Bryan Brown, Senior Extension Associate at NYS Integrated Pest Management, for reviewing the following recommendations:

  • Applying pre-emergent herbicide as a burn down or clean up in fall might be something to consider if you have a large seedbank of horseweed and this method is effective until the next spring. A few good options are Accent® (nicosulfuron, 2) and the premixes Acuron Flexi®,Harness Max®, Kyro®, Resicore®or Resicore XL®.  
  • Rotating in some alternative post applications will reduce the development of herbicide resistance and help with weed control. Some options to consider include: Accent® (nicosulfuron, 2), Aim® (carfentrazon, 14), Armezon Pro® (topramezone, 27), Basis Blend® (rimsulfuron, 2), Stinger® (clopyralid, 4), Warrant® (acetochlor, 14).  
  • Diversifying your weed control options is beneficial to delay herbicide resistance and the potential of decrease of herbicide efficacy as the climate change. Using cultural and/or mechanical practices, such as cover crops, competitive crop rotation, and improving agronomic practices (seed spacing, timing, etc.) will help the crop out-compete the weed population.  
  • Other strategies include mechanical tools such as strategic till, seed destructor, chaff lining, weed zapper, etc. Using precision, spot sprayers, or spray drones.  
  • Horseweed (Conyza canadensis) if exposed to higher temperatures in the early spring will more readily bolt. 

Other Climate Factors

Other Climate Factors 

  • Drought
    • Glyphosate (Roundup®, group 9) was less effective when applied to velvetleaf (Abutilon theophrasti) under drought conditions. Two papers looked at annual sowthistle (Sonchus oleraceus). One of the papers found that efficacy decreased for a resistant biotype, while the other paper found no change in efficacy for resistant biotypes and an increase in efficacy for susceptible biotypes.
  • Decreasing Humidity
    • Glufosinate (Liberty®, group 10) was less effective when applied to wild oat (Avena fatua), Palmer amaranth (Amaranthus palmeri), redroot pigweed (Amaranthus retroflexus), common waterhemp (Amaranthus tuburculatus), and green foxtail (Setaria viridis) under low humidity.
    • Mesotrione (Callisto®, group 27) was less effective when applied to common waterhemp (Amaranthus tuburculatus) under low humidity.

The efficacy of herbicides is expected to either decreaseincrease, or maintain effectiveness depending on the specific chemistryspecies, and climate factor(s) involved. This web page focuses on problematic weeds in corn cropping systems and provides data sourced from the current scientific literature to help build an understanding of how these future shifts might affect weed management. Please note that research to date has mostly focused on glyphosate, which limits information on effective substitutions in weather conditions where glyphosate is less effective. Additionally, only a small group of weed species have been studied, so there are many common weeds with no available information on changing herbicide efficacy. However, given the currently available literature, we conclude that photosynthetic pathway, herbicide resistance, and herbicide chemistries will have the most impact on efficacy and management.  

See our other web pages and fact sheets in this series for information on photosynthetic pathways, herbicide resistance effects, and climate change impacts for additional commodity areas. Growers should refer to the current Cornell Pest Management Guidelines for information on pesticides labeled for use in New York State. Contact an area extension specialist for current information on best practices in weed management and herbicide rotation.

 

Credits

This content was authored by Caroline Marschner, Sharon Bachman, Isabella Colucci, John Pirrung, Sophie Westbrook, and Toni DiTommaso. We would also like to express our gratitude again to Vipan Kumar and Bryan Brown for their invaluable support and expert input on this project and these fact sheets.

Disclaimers

Read the pesticide label prior to use. The label is the law.  The information contained on this page is not a substitute for a pesticide label. Trade names used herein are for convenience only; no endorsement of products is intended, nor is criticism of unnamed products implied.

This work was supported by a joint research and extension program funded by the Cornell University Agricultural Experiment Station (Hatch funds) and Cornell Cooperative Extension (Smith Lever funds) received from the National Institutes for Food and Agriculture (NIFA,) U.S. Department of Agriculture. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.

References