Late-Season Herbicide Applications in Corn
In many parts of Kansas, rainfall over the last month has presented challenges for corn producers. In terms of weed management, pre-emergence herbicides that were applied at planting are likely no longer active, and post-emergence herbicide applications may have been delayed. This scenario may require late-season weed control to protect yield, prevent harvest difficulties, and reduce additions to the weed seed bank.
Table 1 lists products that can be applied to corn over 12 inches tall to control emerged weeds. Atrazine is not labeled for application to corn 12 inches tall or taller, so any herbicides containing atrazine are not listed. If a group 27 herbicide, such as topramezone (Impact, others) or tembotrione (Laudis, others), is applied, pyridate (Tough) can be included instead of atrazine to increase the effectiveness of the group 27 herbicide. Also, note that some of these products recommend or require the use of drop nozzles to reduce crop injury and improve spray coverage on weeds shorter than the crop.
Table 1. Herbicides labeled for corn over 12 inches tall to control emerged weeds.
|
Herbicide (Group) |
Example Product |
Maximum Corn Height or Stage |
Comments |
|
Glufosinate (10) |
Liberty, others |
V6 |
|
|
Tolpyralate (27) |
Shieldex |
V6 or 20 inches |
Can mix with Tough to enhance control |
|
Clopyralid (4) |
Stinger, others |
24 inches |
Fair to good pigweed control |
|
Topramezone (27) |
Armezon, Impact |
V8 |
Can mix with Tough to enhance control |
|
Pyridate (6) |
Tough |
V8 |
Can be used to enhance Group 27 herbicides |
|
Mesotrione (27) |
Callisto, others |
V8 or 30 inches |
Can mix with Tough to enhance control |
|
Glyphosate (9) |
Many |
V8 or 30 inches |
RR2 hybrids use drop nozzles 30 to 48 inches |
|
Nicosulfuron (2) |
Accent |
36 inches |
Use drop nozzles >20 inches |
|
Tembotrione (27) |
Laudis |
V9 |
Can mix with Tough to enhance control |
|
Carfentrazone (14) |
Aim |
14 leaves |
Use drop nozzles > 8 leaves |
|
Bromoxynil (6) |
Moxy, others |
tasseling |
Fair pigweed control |
|
Dicamba (4) |
Clarity others |
tasseling |
Fair to good crop safety |
|
DiFlexx |
V10 |
Good crop safety |
|
|
Status |
V8 or 30 inches |
Good to excellent crop safety |
|
|
2,4-D (4) |
Amine or ester |
tasseling |
Use drop nozzles if corn >8” |
|
Enlist One |
V8 or 30 inches |
Enlist corn hybrids only |
For more detailed information, see the “2026 Chemical Weed Control for Field Crops, Pastures, and Noncropland” guide available online at https://www.bookstore.ksre.ksu.edu/pubs/CHEMWEEDGUIDE.pdf or check with your local K-State Research and Extension office for a paper copy.
The use of trade names is for clarity to readers and does not imply endorsement of a particular product, nor does exclusion imply non-approval. Always consult the herbicide label for the most current use requirements. Users should read and follow all label directions.
Sarah Ganske, Weed Science Extension Specialist
slancaster@ksu.edu
Patrick Geier, Weed Scientist - Southwest Research & Extension Center, Garden City
pgeier@ksu.edu
Jeremie Kouame, Weed Scientist – Agricultural Research Center, Hays
jkouame@ksu.edu