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Dicamba: Time Proven Solutions for Weed Control in Row Crops including Soybean (06/11/20)

The chloroacetamide herbicides (SOA 15) were discovered and commercialized in the 1960s for grass and broadleaf weed control in many crops including soybean.

The chloroacetamide herbicides (SOA 15) were discovered and commercialized in the 1960s for grass and broadleaf weed control in many crops including soybean. Dual Magnum, Harness, Outlook, Warrant and Zidua are commonly used SOA 15 herbicides. These herbicides historically were used preplant or preemergence in row crops. More recently, these herbicides have been used early postemergence following a PRE herbicides in row crops including soybean and sugarbeet where they provided extended residual activity for troublesome weeds including waterhemp. Chloroacetamide herbicides are activated by rainfall totals ranging from 0.25 to 0.75 inch, depending on herbicide and soils and have a reasonably low risk of herbicide resistance since they often are used in a systems approach for weed management with other herbicides.

NDSU research indicates chloroacetamide herbicides timed 21 to 28 days following PRE application or when soybean ranges from the V3 and V5 stage provide good to excellent waterhemp control. In a 2016 experiment, Warrant applied early POST and following Authority MTZ improved season long waterhemp control 27% and 47% compared to Authority MTZ PRE fb PowerMax or Warrant plus PowerMax EPOST in soybean. Similar results have been reported in other low growing crops such as sugarbeet confirming season long waterhemp control when residual herbicides are layered or applied PRE followed by EPOST. Please check product specific label for specific growth stage details. SOA 15 herbicides do not control emerged weeds.

 

Tom Peters

Extension Sugarbeet Agronomist

NDSU & U of MN

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