ISSUE #435

435 - Dual: Another Weapon Against Weeds


Dual Magnum herbicide has finally been labeled for use on sugarbeet in the United States. Dr. Alan Dexter has conducted many research trials on its use since 1985. Dual Magnum will not be a shareholders answer to every weed control problem. It will be one more very good weapon in the annual war on weeds.

Q. How can Dual be used in a weed control program for sugarbeet?

A. Dual can be used as a PPI (Preplant incorporated), PRE (preemerge) or POST applied as a layby treatment.

Q. How is it used most effectively?

A. Applying it right ahead of planting and incorporating it about 1-2 inches deep with seedbed preparation should result in best weed control.


PPI Dual and Nortron gave better weed control than Pre at equal rates (Table 1) Pre Nortron gave better redroot pigweed control than Pre Dual but PPI Dual gave better control of redroot pigweed, common lambsquarters and foxtail spp, than Pre Nortron. PPI Eptam + Ro-Neet gave similar weed control but more sugarbeet injury than PPI Dual or Nortron.

*From Dr. Alan Dexter, Hillsboro and Colfax sites, 1986.

Q. How is Dual used preemerge?

A. It can be applied in a band or broadcast behind the planter, saving a pass across the field.

Q. How much rain is required for activation of the Herbicide?

A. About ½ inch of rain will fully activate Dual herbicide

Q. Which weeds will Dual and Nortron/Etho-SC/Ethotron control?

A. Dual PPI Weed control ratings from the 2003 North Dakota Weed Control Guide are:


Q. If I use PPI or PRE Dual what rate of post emergence herbicides should be used?

A. Don't change microrate use if Dual has been applied, BUT reduce conventional postemergence rates by about 1/3 to reduce potential crop injury when applying over PRE or PPI Dual.

Q. If I use Dual will I reduce the need for postemergence herbicides?

A. Postemergence herbicide use might be reduced by one application but that's not a guarantee. Weed pressure in each field, species of weeds present, and environment all will affect number of POST applications required.

Q. How much incorporation of Dual is required?

A. The shallow tillage done prior to planting should be very adequate, avoid streaking and non-uniformity as much as possible.

Q. Can I tank mix Dual and Roundup as a PRE application?

A. Yes, Dual and Roundup or Gramoxone can be safely tank mixed.

Q. How does Dual compare with Norton (or generics containing ethofumesate) for weed control?

A. PPI Dual will be similar or slightly better in weed control than Nortron or ethofumesate containing generic products applied PRE. Watch DTN and the Internet for more information.

Q. Will Dual cause serious crop injury?

A. Dual occasionally has caused noticeable sugarbeet stunting and stand loss. The risk increases as soil clay content and organic matter content declines. Sugarbeet plants recover well from early season stunting. Consider increasing the sugarbeet seeding rate when using Dual. Ethofumesate (Nortron, Etho-SC, Ethotron) is less likely to injure sugarbeet than Dual.

Q. Will Dual carryover and cause crop injury in 2004?

A. No - Dual will not carryover and damage any crop.

Q. How does Dual compare to Outlook as a layby treatment?

A. Dual and Outlook should perform almost exactly the same as layby treatments. Don't apply either product as a layby until beets have at least 4 true leaves.

Q. Which soil applied herbicide is best for Kochia?

A. Nortron, (Etho SC or Ethotron) are far better products on Kochia than is Dual.

Q. Can fertilizer be impregnated with Dual and then applied?

A. Yes, providing fertilizer is applied at a rate of 200-700 lb/acre.