May 30, 2002

Weed Control Tips for Replanted Sugarbeets

Red River Valley sugarbeet growers will replant approximately 60,000 acres because of a severe frost on May 24. Those growers may want to consider some options for postemergence weed control, according to Alan Dexter, North Dakota State University and University of Minnesota sugarbeet weed specialist.

"Replanting fields that were treated with a band of Nortron or Etho SC may present a problem if emerged weeds are present in the field," Dexter says. "Normally the field could be tilled to control the weeds prior to replanting, but the tillage will move and dilute the bands of herbicides so the value of the herbicides will be lost. Nortron and Etho SC provide season-long weed control, so seeding back into the bands is desirable."

An option growers may want to consider is seeding back into the original sugarbeet row without tillage and then use Roundup to control emerged weeds. "Unfortunately, Roundup will kill any emerged sugarbeet plants that survived the replanting," Dexter says. "However, killing the emerged weeds is more important."

Because of recent weather conditions, wild oat, volunteer grain and oats or barley seeded as a cover crop have gotten off to a faster start than sugarbeets this year. Postemergence grass herbicides will control large grass, so control is still possible but should be applied as soon as possible, notes Dexter. Grass growing in the sugarbeet row needs to be treated with herbicide at the three-leaf stage or sooner while grass between the rows needs to be sprayed or cultivated by the 5-leaf stage or sooner to avoid yield loss due to competition between the grass and sugarbeet.

"Everyone wants to save money on herbicide costs so questions have been common about leaving one of the herbicide components out of the micro-rate," Dexter says. "Betanex, Betamix or Progress must be included as well as UpBeet and methylated seed oil. Stinger is needed if the field has wild buckwheat, common lambsquarter, ragweed, cocklebur, maxshelder, smartweed, nightshade or Canada thistle. Adding extra Nortron to the micro-rate helps on weed control but does not substitute for Stinger."

Growers who did not replant but have less than optimum stands should consider Lay-By Outlook to control late emerging weeds, according to Dexter. "Outlook should be applied at 21 fluid ounces per acre when sugarbeet plants are in the early 4-leaf stage."

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Source: Alan Dexter, (701) 231-8131, adexter@ndsuext.nodak.edu
Editor: Rich Mattern, (701) 231-6136, rmattern@ndsuext.nodak.edu