Print view

When should Betamix be tank-mixed with glyphosate in RR sugarbeet?

Courtesy Dr. Tom Peters (Extension Sugarbeet Agronomist NDSU and U of MN)

American Crystal Sugar is moving Betamix inventory from storage to farms. The obvious questions are should sugarbeet farmers take Betamix and when should they add Betamix to the tankmix? Betamix will last a lifetime provided it is properly stored to ensure it does not freeze. I recommend farmers take Betamix since I believe it will be useful for control of tough-to-control broadleaf weeds in sugarbeet.

Betamix is a postemergence herbicide for the control of annual broadleaf weeds in sugarbeet including kochia, pigweed species including waterhemp, lambsquarters and common ragweed. Betamix is a contact herbicide that should be applied in spray volumes ranging from 15 to 20 gallons per acre and at a spray pressure to ensure good coverage to small, actively growing weeds. Oil adjuvants (Crop Oil Concentrate and Methylated Seed Oil) greatly enhance oil soluble herbicides like Betamix but antagonize glyphosate. MSO based ‘high surfactant oil concentrate’ adjuvants (HSMOC) contain a higher concentration of surfactant COC and MSO and enhance oil soluble herbicides without decreasing glyphosate activity. Apply oil adjuvants on an area basis (i.e. pt/A) rather than a volume basis (1% v/v).

Sugarbeet injury occasionally occurs from Betamix. Sugarbeet with four true leaves are less susceptible to injury than smaller sugarbeet. Sugarbeet gain additional tolerance as they become larger than the four-leaf stage. Risk of sugarbeet injury is reduced by starting application in late afternoon so cooler temperatures follow application. Risk of injury is increased by factors such as recent flooding, high temperature, and a sudden change from a cool, cloudy environment to a hot, sunny environment. 

Consider addition of Betamix to the tank-mix for control of glyphosate resistant weeds including kochia, waterhemp, and common ragweed. While I am unaware of glyphosate resistant lambsquarters, Betamix applied with glyphosate will improve efficacy, especially under dry conditions. Please consider the following suggestions:

 ¹Betamix at 8-12 fl oz/A on cotyledon, 12-16 fl oz/A on 2-lf, 16-24 fl oz/A on 4-lf and 24-34 fl oz/A on sugarbeet > 6-lf.

²Assumes two glyphosate sprays before V8 sugarbeet. Apply glyphosate at 32 fl oz/A if one application before V8 sugarbeet. Apply glyphosate at 22 fl oz/A after V8 sugarbeet stage. Make repeat application(s) at approximately 14 day intervals.

Addition of ethofumesate at 4 fl oz/A with Betamix plus glyphosate improves control, especially on tough-to-control weeds such as waterhemp and kochia. Use the lower range of the Betamix recommendations as sugarbeet injury maybe greater.