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Most Common Sugarbeet Weed Control Question, Week of May 10 (05/20/21)

Question. Why is there so much common ragweed and how can I control common ragweed in sugarbeet?

Question. Why is there so much common ragweed and how can I control common ragweed in sugarbeet?

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Common ragweed germinates and emerges deeper than small seeded broadleaf weeds like common lambsquarters, redroot pigweed, and waterhemp. Dr. Joe Ikley, NDSU Extension Weed Control Specialist, indicates common ragweed is germinating from approximately a 2-inch depth in the soil. This is much deeper than where lambsquarters and pigweed germinate, and the ragweed is probably germinating in moisture. Common ragweed emerges in the spring after kochia and lambsquarters but before pigweed species.

Common ragweed has become more widespread with the increase in soybean and dry bean in Minnesota and North Dakota. Common ragweed is not controlled by group 15 herbicides (chloroacetamides), and fields with ALS (group 2) and glyphosate (group 9) resistant common ragweed biotypes are frequent. There were few POST options for common ragweed control before the advent of group 4 and group 10 tolerant soybean traits. Common ragweed remains viable in the seed bank longer than pigweed species.

In sugarbeet, Stinger or Stinger HL (clopyralid, group 4) are our most affective herbicides for controlling common ragweed. Stinger should be applied at 3 fl oz/A or Stinger HL should be applied at 1.8 fl oz/A when common ragweed is less than 2-inch tall. Be prepared for a repeat application 14 days after the first application.

 

Tom Peters

Extension Sugarbeet Agronomist

NDSU & U of MN

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