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. As you make seeding plans, be sure to consider the herbicides you use in your summer crops. Table 1 highlights some herbicides used in summer crops that may or may not have rotation restrictions for canola. As you consider this information, please remember that the 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

Crop use

Half-life

(days)

Rotation interval

Comments

Aatrex, others

atrazine

Corn, grain sorghum

29

one year
to avoid crop injury

 

Ally, others

metsulfuron

grain sorghum, wheat

13

34 months and at least 28” precipitation

Less if successful bioassay

Amber, others

triasulfuron

wheat

39

 at least 4 months

Also requires bioassay

Balance Flexx, others

isoxaflutole

corn

1.3

18 months

Also requires 15” of precipitation

Beyond, others

Imazamox

Clearfield wheat, soybean

17

26 months

18 months for Clearfield canola

Callisto, others

mesotrione

corn

5

10 months

 

Classic

chlorimuron

soybean

28

9 to 18 months

See label for details

Talinor, Acuron (others)

bicyclopyrone

corn, wheat

213

18 months

 

Dimetric, others

metribuzin

soybean

19

18 months

 

Dual II Magnum, others

metolachlor

corn, grain sorghum, soybean

23

12 months

 

Glean, others

chlorsulfuron

wheat

36

bioassay required

 

Harmony, others

thifensulfuron

wheat

10

45 days

 

Harness, Warrant, others

acetochlor

corn, grain sorghum, soybean

12

Not listed

 

Outlook, others

dimethenamid

corn, grain sorghum, soybean

16

4 to 6 months

Interval increases with increasing rate

Permit, others

halosulfuron

corn, grain sorghum

14

15 months

Bioassay if drought or cool conditions prevail

Python, others

flumetsulam

corn, soybean

45

26 months

Also requires bioassay

Spartan, other

sulfentrazone

soybean

541

24 months

 

Valor, others

flumioxazin

soybean, fallow, burndown

18

6 or 12 months

6 months if tilled

Zidua, others

pyroxasulfone

corn, soybean, wheat

22

12 to 18 months

Interval increases with increasing rate

FirstRate

cloransulam

soybean

10

18 months

 

Pursuit

imazethapyr

soybean

51

40 months

Also requires bioassay

Reflex

fomesafen

soybean

86

18 months

 

 

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:  fire herbicides canola winter canola