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