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Emerged Weeds in Sugarbeet (05/20/21)

Our 2021 sugarbeet crop is planted and stands are spotty in many regions. Kochia, common lambsquarters, common ragweed, and pigweed are emerging but generally have been spotty despite lack of rainfall to incorporate preemergence herbicides.

Our 2021 sugarbeet crop is planted and stands are spotty in many regions. Kochia, common lambsquarters, common ragweed, and pigweed are emerging but generally have been spotty despite lack of rainfall to incorporate preemergence herbicides. I am writing with my best recommendations for managing waterhemp escapes in sugarbeet. But most important, producers need a sense of urgency against weed escapes, especially waterhemp since small waterhemp become large waterhemp in a matter of days and weeks. I recommend two options for postemergence waterhemp control in sugarbeet.

Apply glyphosate with Stinger and ethofumesate at 4 to 6 fl oz/A plus ammonium sulfate and high surfactant methylated oil concentrate (HSMOC) at 1 pt/A. We have observed approximately 75% control of 1-inch glyphosate resistant waterhemp. Some of you might be surprised by this level of control. Two reasons: a) first our fields are a mixture of glyphosate susceptible and resistant populations; and b) according to Dr. Todd Gains, Molecular Weed Science and Associate Professor, Colorado State University, glyphosate resistance is quantitative and not qualitative meaning glyphosate may control 1-to 2-inch waterhemp with resistant alleles but misses 2- to 4-inch waterhemp.

Clopyralid (Stinger) does not control waterhemp. However, Stinger with Roundup PowerMax and ethofumesate improved control of waterhemp up to 1-inch 20% and 27%, 12 and 25 DAT, respectively, compared to Roundup PowerMax with ethofumesate alone in a greenhouse experiment (Figure 1). However, the waterhemp control advantage from Stinger with PowerMax and ethofumesate was less once waterhemp grew to 2-inch.

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Some producers have access to Betamix. Betamix is effective on pigweed species such as waterhemp but becomes less reliable once watehemp are greater than 2-inch tall. Betamix rate is dependent on waterhemp size and sugarbeet growth stage. Apply Betamix in at least 15 gpa water carrier and nozzles delivering good coverage. Betamix can be applied in mixtures but be careful of complex mixtures that may increase sugarbeet injury.

 

 

Tom Peters

Extension Sugarbeet Agronomist

NDSU & U of MN

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