Got Weeds in Your Flowers?

15 Jul Got Weeds in Your Flowers?

Growers should scout fields now to evaluate pre-emerge sunflower weed control performance and identify weed species and populations. Post-emergent applications are most effective when weeds are small.

Control weeds post emergent in your Sunflower Crop.

• Post planting weed control especially for broadleaf weeds in Sunflower production has long been an issue growers have struggled to get done well. While a pre-emergent program keeps a clean field early in the season escapes and late emerging weeds do happen.    If post emergent weeds are not controlled several species can result in significant yield loss.   The charts below represent yield losses from just a few grass and broadleaf weeds per foot of row.

*Sunflower Production – NDSU Extension Service, ND Ag.Exp.Sta,  September 2007

• Growers have had excellent post emergent herbicide options for controlling grasses in broadleaf crops (including Sunflower) for many years. The ACCase Inhibitor family of herbicides provides excellent control of most grass problems including volunteer corn in Sunflower.   They are applied after the sunflowers have emerged and while grasses are less than 6 inches tall.
  • ACCase herbicides available include Poast, Assure, and Select

• Fortunately, the introduction of herbicide tolerant hybrids over the past 10 years has given growers the tools to better control broadleaf weeds helping to make Sunflower growing easier and more successful.
  • Clearfield and Clearfield Plus are tolerant to the Imidazoline family of herbicides.  
    • Imi-tolerant hybrids have been on the market since 2005. Many current hybrids are top of the line high yielding choices for growers.
    • Clearfield Plus genetics offer growers a bit more flexibility with herbicide rates and timing.
    • Beyond ® is the registered post-emergent herbicide for use with these hybrids.
    • These hybrids are not Genetically Modified so will fit markets demanding non-GMO products.
    • Beyond ® controls a wide range of broadleaf and grass weeds. (see chart below)
  • Express Sun hybrids are tolerant to the ALS family of herbicides.
    • Sulfonyl-urea tolerant hybrids became available to growers two years following Clearfield. Like Clearfield there are high yielding excellent hybrids available.
    • Express ® is the registered herbicide for post-emergent use with these hybrids.
    • Similar to Clearfield – Express Sun hybrids are non-GMO
    • Express ® controls a similar range of weeds as Beyond ®. (see chart below)

If field scouting identifies weed problems in your Sunflowers you can successfully manage them, prevent yield loss, and protect your profit potential.   The chart below shows the relative effectiveness of the registered herbicides for control of several weed species.   Keep in mind that Kochia, Pigweed, and Waterhemp have developed resistance to ACCase and ALS chemistries and if those biotypes are present Beyond ® and Express ® will not control them.

*Sunflower Production – NDSU Extension Service, ND Ag.Exp.Sta,  Figure 12 December 2020

https://www.ag.ndsu.edu/publications/crops/sunflower-production-guide#section-19