Herbicide carryover considerations when planting after wheat

Growers considering re-cropping wheat fields need to consider the herbicide program that was used in the wheat crop. Many wheat herbicides have fairly long crop rotation restrictions. Selected herbicides and rotation intervals to certain crops are listed in Table 1.

Herbicide break down is affected by many factors such as soil pH so be sure to check herbicide labels for specific information for your fields, particularly for the intervals marked with an asterisk in Table 1. Additionally, some labels allow shorter intervals in the case of catastrophic crop failure, as long as the producer is willing to accept the risk of crop injury. If you are in doubt about your decision, consider conducting a field bioassay to determine if it is safe to plant the crop you are considering. A field bioassay is simply a short strip of crop planted across the direction of the herbicide application. Plants in the strip are monitored for herbicide injury as they emerge. 

 

Table 1. Minimum rotation intervals for key summer crops following application of selected wheat herbicides in Kansas.

 

Minimum rotation interval
(conventional varieties/hybrids)

Herbicide (active ingredient)

Grain sorghum

Corn

Soybean

Sunflower

Agility (dicamba, thifensulfuron, tribenuron, metsulfuron)

4 m*

4-12 m*

4-34 m*

10-22 m*

Ally, others (metsulfuron)

4-10 m*

12 m*

4-34 m*

22 m*

Beyond (imazamox)

9 m

0-8.5 m*

None

0-9 m*

Everest 3.0 (flucarbazone)

9-18 m*

9-18 m*

4-12 m*

4-9 m*

Glean (chlorsulfuron)

4-48 m*

Bioassay

4 m*

Bioassay

Harmony (thifensulfuron)

None

None

None

45 d

Huskie (pyrasulfotole, bromoxynil)

7 d

4 m

4 m

9 m

Outrider (sulfosulfuron)

3 m

3 m

3 m

3 m

Peak (prosulfuron)

1 m*

1 m*

10 m*

22 m*

PowerFlex HL (pyroxsulam)

3-9 m*

9 m

3-5 m*

3-9 m*

Quelex (haluxifen, florasulam)

45 d-3 m*

45 d-3 m*

45 d-3 m*

3 m

Rave (triasulfuron, dicamba)

14-24 m*

14-36 m*

11-36 m*

24 m*

WideMatch (fluroxypyr, clopyralid)

10.5 m

None

10.5 m

10.5 m

Abbreviations: d=day, m=month

*Consult herbicide label for geographic, soil, precipitation, application rate, or other conditions associated with this crop rotation interval.

 

Many of the herbicides listed in Table 1 are ALS-inhibiting herbicides that are associated with resistance in certain varieties or hybrids. Some examples are Clearfield sunflowers, which can be planted following Beyond, or Bolt soybeans which have a shorter rotation interval following sulfonylurea herbicides such as Ally.  

 

 

Sarah Lancaster, Extension Weed Science Specialist
slancaster@ksu.edu

 

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.