Winter Pre-Emergence Herbicide Trial is Underway

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It may be somewhat slower for nursery production in the winter months, but rest assured that cool season weeds are in full tilt and will soon be a major headache for growers as they move into the “busier” times of the 2024 spring season. Pre-emergence herbicides can be an essential tool for container and field nursery growers during this critical time of the season, but limited research exists on how effective some of the more popular products are for cool season (winter annual) weeds, which includes longevity of the products. Winter weed management is especially important since herbicides cannot, by law, be applied after overwintering houses have been covered for the season.

The focus of this project is to determine the efficacy and longevity of nine widely available pre-emergence herbicides for winter annual weed control in container nurseries:

  • Snapshot (trifluarlin + isoxaben)
  • Freehand (dimethenamid-p + pendimethalin)
  • Broadstar (flumioxazin)
  • Marengo (indaziflam)
  • Biathlon (oxyflurofen + prodiamine)
  • Pendulum (pendimethalin)
  • Fortress (isoxaben + dithiopyr)
  • Gemini (isoxaben + prodiamine)
  • Ronstar (oxadiazon)

We mimicked a final pre-emergence herbicide application before houses were covered at the end of November and the project will last approximately 5 months, ending sometime in March. The trial will conclude with field day for agents and interested nursery growers. Date for the field day is TBD but will be announced well in advance to ensure plenty of time for planning–if you are interested and would like to be notified in advance, please contact Sam Marshall at (828) 476-8485 (text or call) or at wsmarsh2@ncsu.edu to get added to the notification list! Use “Herbicide Field Day” in the subject line. We plan to replicate this study for field production nurseries at a later date, so please stay tuned.

We would like to extend a special ‘thank you’ to the growers at Stowe’s Nursery in Gastonia, NC for their cooperation and support for the duration of this study. Click here to learn more about the nursery and what they offer.

If you own, operate, and/or work at a container production nursery and are unable to attend this in-person event, results of this study will be shared at a later time.Plants in a greenhouse.