Recent developments associated with market opportunities for winter canola may lead to increased planting in the fall of 2023 and beyond. As you make seeding plans, be sure to consider the herbicides you use or have used in your fall and summer crops. Table 1 highlights some herbicides used in fall and summer crops that may or may not have rotation restrictions for canola. As you consider this information, please remember that rotation intervals required by the EPA only consider the time that is required to ensure no illegal herbicide residues are found in the second crop. However, in some cases, additional information can be provided by the herbicide registrant regarding the potential for injury. When appropriate, that information will be noted in Table 1.
Table 1. Active ingredients, field half-lives, and crop rotation intervals of some herbicides applied to summer crops that may be of concern for winter canola.
|
Herbicide |
Active ingredient |
Half-life (days) |
Rotation interval |
Comments |
|
Aatrex, others |
atrazine |
29 |
one year |
|
|
Balance Flexx, others |
isoxaflutole |
1.3 |
18 months |
Also requires 15” of precipitation |
|
Beyond * |
imazamox |
30-60 |
18 months |
|
|
Callisto, others |
mesotrione |
5 |
10 months |
|
|
Classic |
chlorimuron |
28 |
9 to 18 months |
See label for details |
|
Component of Acuron (others) |
bicyclopyrone |
213 |
18 months |
|
|
Dimetric, others |
metribuzin |
19 |
18 months |
|
|
Dual II Magnum, others |
S-metolachlor |
23 |
12 months |
|
|
Finesse * |
chlorsulfuron metsulfuron |
14-42 |
|
Field bioassay required |
|
Harmony, others |
thifensulfuron |
10 |
45 days |
|
|
Harness, Warrant, others |
acetochlor |
12 |
Not listed |
|
|
Huskie |
pyrasulfotole |
30 |
9 months |
|
|
Outlook, others |
dimethenamid-P |
16 |
4 to 6 months |
Interval increases with increasing rate |
|
Permit, others |
halosulfuron |
14 |
15 months |
Bioassay if drought or cool conditions prevail |
|
Powerflex HL |
pyroxsulam |
13 |
9 months |
|
|
Python, others |
flumetsulam |
45 |
26 months |
Also requires bioassay |
|
Spartan, other |
sulfentrazone |
541 |
24 months |
|
|
Valor, others |
flumioxazin |
18 |
6 or 12 months |
6 months if tilled |
|
Zidua, others |
pyroxasulfone |
22 |
12 to 18 months |
Interval increases with increasing rate |
|
FirstRate |
cloransulam |
10 |
18 months |
|
|
Pursuit |
imazethapyr |
51 |
40 months |
Also requires bioassay |
|
Reflex |
fomesafen |
86 |
18 months |
|
* To avoid plant back restrictions for canola, consider planting a Clearfield® winter canola after applying Beyond in wheat, and a sulfonylurea herbicide carryover tolerant winter canola after applying Finesse or similar Group 2 herbicides in wheat.
For producers using the CoAXium® wheat system, remember that there is no rotation restriction for canola. However, to protect the efficacy of controlling weeds in both crops, it is recommended to rotate herbicide modes of action.
For more detailed information, see the “2023 Chemical Weed Control for Field Crops, Pastures, and Noncropland” guide available online at https://bookstore.ksre.ksu.edu/pubs/SRP1176.pdf or check with your local K-State Research and Extension office for a paper copy.
For more information on canola planting considerations, see the “Great Plains Canola Production Handbook” available at https://www.bookstore.ksre.ksu.edu/pubs/mf2734.pdf.
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.
Sarah Lancaster, Weed Management Specialist
slancaster@ksu.edu
Mike Stamm, Canola Breeder
mjstamm@ksu.edu