Planting winter canola? Be aware of rotation restrictions with herbicides

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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
to avoid crop injury

 

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


Tags:  label requirements herbicides canola winter canola