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Postemergence Herbicide Treatments in Sugarbeet (05/21/20)

Plant 2020 will be a dichotomy of growth stages depending on region of the sugarbeet producing area.

Plant 2020 will be a dichotomy of growth stages depending on region of the sugarbeet producing area. In general, sugarbeet growth stage is much more advanced in southern and west central Minnesota and the southern part of the Red River Valley (RRV). Contrast that to areas between Hillsboro, ND and Warren, MN were large tracts of acreage remain to be planted. However, broadleaf weeds are responding to rainfall and increasing air temperatures and will quickly need to be managed.

Soil applied herbicides are highly recommended for fields to be planted, especially in areas where waterhemp is identified as the most important weed control challenge in sugarbeet. Soil applied herbicides should be applied preplant or preemergence depending on the Producers appetite for risk of activation. We know waterhemp has emerged as far north as St. Thomas. Thus, it is highly recommended herbicides be applied preplant unless rainfall is imminent after application. Likewise, kochia is emerging and will continue to do so in response to tillage.

Broadleaf weeds are our most important weed control challenges in sugarbeet. Our five most important weeds are waterhemp, common ragweed, common lambsquarters, giant ragweed, and kochia. In addition, some areas identify biennial wormwood or redroot pigweed as their most important weed control challenges. Glyphosate should be included in every postemergence application since nearly 100% of sugarbeet production uses Roundup Ready sugarbeet seed. Glyphosate can be mixed with Stinger for control of ragweed species and biennial wormwood. Stinger is active on four weed families, composite, legumes, buckwheat, and nightshade family weed species. Stinger has very little activity on pigweed species or common lambsquarters. We recommend producers mix ethofumesate (Nortron, Ethotron, Ethofumesate 4 SC) with glyphosate and Stinger. NDSU / UMN research conducted over multiple environments has reported at least a 15% increase in waterhemp control when 4 to 6 fluid ounces ethofumesate is mixed with glyphosate since ethofumesate has been found to alter cuticular waxes and increasing herbicide absorption.

Glyphosate alone or mixtures should be applied with ammonium sulfate (AMS). AMS enhances glyphosate absorption and translocation and deactivates antagonist hard water salts (Na, Ca, Mg, Fe). As spray droplet water evaporates, sulfate from AMS binds with antagonistic salts and prevents binding with glyphosate. In addition, ammonium from AMS binds with glyphosate resulting in greater absorption and weed control. We also recommend a non-ionic surfactant (NIS) with glyphosate unless prohibited by the label. However, oil-based formulations like Stinger, ethofumesate or Betamix tank-mixed with glyphosate perform better with oil adjuvants (crop oil concentrate or methylated seed oil) than NIS. High surfactant oil concentrate (HSMOC) adjuvants have a higher surfactant concentration than COC or MSO and enhance oil solute herbicides without decreasing glyphosate activity.

 

Tom Peters

Extension Sugarbeet Agronomist

NDSU & U of MN

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