April 17, 2003

 

Dual Magnum Receives Registration For Sugarbeet

Dual Magnum recently received EPA registration for use on sugarbeet. Dual Magnum can be fall-applied, incorporated prior to seeding, applied preemergence after seeding or as a lay-by treatment, says Alan Dexter, North Dakota State University and University of Minnesota sugarbeet weed specialist.

"Optimum Dual Magnum rates vary with soil organic matter content and application timing so the label should be consulted for rate selection," Dexter says. "Lay-by treatments of Dual Magnum alone may be applied as soon as the sugarbeet reach the two-true-leaf stage. Lay-by Dual Magnum in combination with other herbicides should be applied after the sugarbeet has four true leaves to reduce the risk of sugarbeet injury."

Preplant incorporated Dual Magnum has provided more consistent weed control than preemergence Dual Magnum because the rainfall necessary to activate preemergence Dual Magnum may not occur for several days. Dual Magnum is degraded by sunlight and half of the applied active ingredient can disappear if the herbicide lies on the soil surface for eight to 10 days without rain or incorporation, Dexter notes. Dual Magnum will provide weed control for six to eight weeks after application.

Incorporation of Dual Magnum does not need to be deep but uniform incorporation is important. The incorporating tool can be run through a strip of lime or flour to evaluate uniformity of distribution in the soil. Incorporation methods that leave streaks should be avoided. Two passes with the incorporating tool may be needed to achieve uniform distribution.

"Dual Magnum may cause occasional injury to sugarbeet. In past experiments in North Dakota and Minnesota, 0 to 17 percent injury was observed at eight of nine locations. That is not a worrisome level of injury," Dexter says. "However, injury was 26 percent at the ninth location and this level of injury was a concern. Seeding rates may be increased as a hedge against stand loss from Dual Magnum. Injury would be expected to be increased with slow emergence in wet, cool soils and on soils with less clay and organic matter.

Stunting of sugarbeet from Dual Magnum would not be expected to cause yield loss but stand loss from Dual Magnum may cause yield loss if the remaining sugarbeet population is insufficient for optimum yield or if the population has gaps that allow late weed establishment."

Dual Magnum is rated to provide good to excellent control of pigweed species, green foxtail and yellow foxtail. Dual Magnum is rated as fair on wild oats, common lambsquarters, Russian thistle and common ragweed.

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Source: Alan Dexter, (701) 231-8131, alan.dexter@ndsu.nodak.edu
Editor: Rich Mattern, (701) 231-6136, richard.mattern@ndsu.nodak.edu