By Nick Arneson (UW-Madison Weed Science Outreach Specialist), David Wang (UW-Madison Undergraduate Research Scholar) and Rodrigo Werle (UW-Madison Extension Cropping Systems Weed Scientist)
With the growing interest in producing industrial hemp in Wisconsin and beyond, it is important to pay close attention to rotation interval restrictions when planting this crop in conventional production fields where herbicides are adopted. Though no synthetic herbicides are labeled for weed control in industrial hemp in the United States at this time, it’s important to keep in mind that herbicides sprayed in previous crops can have an impact on the industrial hemp crop establishment and development. Moreover, the pesticide label is the law and should be followed accordingly.
Below you will find a comprehensive list of herbicides commonly used in corn-soybean rotations and their respective plant rotation restrictions (in months after application) for industrial hemp planting according to their respective labels. Note that the most restrictive interval for each product is listed below (for some products the rotation restriction may be shorter depending upon rate used, geography, soil pH, annual precipitation, etc.; please double check the label). Since industrial hemp is a new crop and thus not part of current label languages, its rotational restrictions fall under “other crops” when searching for this information in the product labels. See video “Weed Talk: 2019 Industrial Hemp Herbicide Carryover Considerations” for more information.
Rotation Restrictions Before Planting Industrial Hemp (in Months After Application):
- 0 months = Cadet, Cobra, Glyphosate 4 Plus, Glyphosate 5.4, Gramoxone SL 2.0, Roundup PowerMAX
- 1 month = Fusilade DX, Resource, Select Max
- 1.5 months = Harmony SG
- 3 months = 2,4-D (e.g., 2,4-D Amine, Barrage HF, Salvo, Shredder 2,4-D LV4)
- 4 months = Assure II, dicamba (e.g., Clarity, Engenia, Fexapan, Status, XtendiMax)
- 6 months = Liberty 280
- 9 months = Confidence, Harness, Outlook, Sharpen, Verdict, Warrant
- 12 months = Aim, Authority Elite, Boundary, Cinch, Command 3ME, Dual II Magnum, Parallel
- 18 months = Anthem, Anthem Maxx, Armezon, Authority MTZ, Balance Flexx, Basis Blend, Beacon, Callisto, Callisto GT, Corvus, Dimetric DF 75%, FirstRate, Halex GT, Impact, Instigate, Lumax EZ, Prefix, Prequel, Raptor, Require Q, Resolve DF, Resolve Q, Resolve SG, Rowel, Solstice, Spirit, Valor SX, Valor EZ, Vise, Zemax, Zidua, Zidua SC
- 24 months = Prowl H2O
- 26 months = Hornet, SureStart II, TripleFLEX
- 30 months = Authority Assist, Authority First, Canopy, Classic, Enlite, Envive, Rowel FX, Sonic, Synchrony, Trivence, Valor XLT
- 36 months = Authority Maxx, Authority XL, Permit
- 40 months = Extreme, Optill, Optill PRO, Pursuit, Torment
We will soon release an in-detail publication with additional information on how herbicide rates and soil characteristics influence rotational Industrial Hemp crop restrictions. Stay tuned!
Always read, understand and follow the pesticide label.