Dual® II Magnum® Herbicide



Dual II Magnum is registered for use on your most important crops: Corn (hybrid, silage, seed, swe...

For management of

Dual II Magnum is registered for outstanding control of all these weeds: American Nightshade1...

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Application Information

When applied alone, use Dual II Magnum at the following rates: CORN: 1.25 – 1.75 L/ha (...

Water Volume

Spray volume — minimum 15 gallons per acre. The use of higher water volumes and larger spra...
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application info

Technical Information

Chemistry Group

Group 15 Herbicide ; Active Ingredient: S-Metolachlor

Active ingredients

S-Metolachlor and R-enantiomer

PHI: corn (seed & silage): 80 days sweet corn: 45 days
REI: 12 hours

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technical info

Label and SDS

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About this Product

Dual II Magnum provides long lasting residual weed control in corn, soybeans and other crops. Its wide window of application will suit your timing needs. Dual II Magnum has a wide choice of tank mix partners, providing one-pass control of your weed pests.

Dual II Magnum contains the unique safener Benoxacor. This added ingredient virtually eliminates any risk of herbicide injury to your corn crop.

Product Benefits

  • Better -- with the assurance of complete crop safety from the added component of Benoxacor.
  • Longer -- lasts longer than any other corn herbicide by providing excellent residual weed control for up to 14 weeks after application.
  • Stronger -- controls even tough weeds like nightshade and nutsedge with a lower more active rate.
  • Wide choice of tank mix partners -- so you can spray for more weeds in one pass over your field. Enjoy the flexibility of choice.
  • Wide window of application, up to 50 days -- Ideal for the application timing you prefer.


Case: 2x10 L
Tote: 450 L


Dual II Magnum is registered for use on your most important crops:
  • Corn (hybrid, silage, seed, sweet)
  • Soybeans
  • Dry common beans (white, kidney, pinto, cranberry, black)
  • Snap common beans (yellow and green)
  • Potatoes
  • Lima Beans
  • Sugar Beets
  • Transplanted tomatoes
  • Rutabagas
  • Sweet white lupins
  • Peas (grown for processing)
  • Certain forestry species
  • Fruit trees
  • Newly planted strawberries
  • Transplanted broccoli, cabbage and cauliflower

For management of

Dual II Magnum is registered for outstanding control of all these weeds:
  • American Nightshade1
  • Barnyard Grass
  • Eastern Black Nightshade1
  • Crabgrass (smooth, hairy)
  • Fall Panicum
  • Foxtail (giant, green and yellow)
  • Old Witchgrass
  • Redroot Pigweed3 (suppression only)
  • Yellow Nutsedge2
1Pre-emergent treatments give better control than pre-plant surface, pre-plant incorporated or post-emergent treatments.
2Pre-plant incorporated treatment only. Extended periods of dry, hot weather following application may result in reduced nutsedge control.
3Pre-plant incorporated and pre-emergent treatments only.

Application Information

Use Rates

When applied alone, use Dual II Magnum at the following rates:

CORN: 1.25 – 1.75 L/ha (0.5 – 0.7 L/ac)*. A 12 L jug treats approximately 17-24 acres.

SOYBEANS: 1.15 – 1.75 L/ha (0.46 – 0.7 L/ac)*.. A 12 L jug treats approximately 17-26 acres. *Use the higher rate for heavy infestations of weeds.

POTATOES: 1.25 -1.75 L /ha (0.5-0.7 L/ac).  Use higher rate of Dual II Magnum for heavier weed problems.

Water Volume

Spray volume — minimum 15 gallons per acre. The use of higher water volumes and larger spray tip sizes will generally increase spray deposition and reduce drift. Keep bypass line at bottom of tank to minimize foaming. Use 16 mesh suction screens, 50 mesh line and tip screens.

Application Method


Application Information

Dual II Magnum provides different application timing options to suit your farm.

Preplant Surface Applications

  • Best opportunity for rains to move herbicide into the weed germination zone.
  • For minimum tillage (reduced tillage) and no-till (zero-till) systems in corn and soybeans.
  • Applications may be made up to 30 days before planting.

Preplant Incorporated Applications

  • Immediate incorporation is not necessary.
  • Incorporation should include rolling or western harrows (see label for equipment, depth and speed recommendations).
  • Best method for nutsedge control.

Pre-emergent Applications

  • Apply evenly to a firm lump-free seedbed.
  • Rain is required to activate within 10 days, or a shallow cultivation or use of a rotary hoe is necessary.
  • Pre-emergent applications may also be made in reduced tillage, ridge tillage, and no-till systems in corn and soybeans.
  • Do not apply Dual II Magnum at ground crack or if potatoes have emerged.
  • Do not apply on the Potato variety Superior.
  • Best results are achieved when applied before weeds pass the 2-leaf stage.

Early Post-emergent Application (Eastern Canada and in corn ONLY)

  • Apply when corn is in the spike to 2-leaf stage and before weeds pass the 2-leaf stage.
  • DO NOT tank-mix with fluid fertilizers, oils, oil concentrates or surfactants.
  • Do not graze/feed or harvest corn within 80 days of making a post-emergent application.

Caution: Do not apply to soils with less than 1% or more than 10% organic matter. Winter cereals may be planted 4 ½ months following application. If drought conditions persist after either a surface pre-plant, annual grass control may not be adequate. 

Mixing Order

  1. Fill spray tank ½ full with carrier. Start gentle agitation.
  2. Add wettable powder or wettable granule tank-mix partner, if applicable. Slurry these products with water first if using liquied fertilizers as the carrier.
  3. Add liquid flowable tank-mix partner, if applicable, and agitate thoroughly.
  4. Fill tank 9/10 full of carrier and add Dual II Magnum and other emulsifiable concentrate or solution tank-mix partners.
  5. Top off tank with carrier, maintain agitation and spray.
  6. Do not let stand without agitation.
  7. Sprayer equipment should be thoroughly flushed with clean water and drained before and after use of Dual II Magnum and its tank mixes.

WALES Symbol: E

Effects of Weather

  • For pre-emergent applications, rainfall is required within 10 days of application on a shallow cultivation or use of a rotary hoe is necessary.
  • On sandy soils, heavy rainfall following an incorporated treatment may move the herbicide out of the zone of activity.

Use Restrictions

  • Re-entry interval: 12 hours
  • Freedom to rotate to any crop the following year

Tank Mixes

There is a wide choice of tank mix options for use in corn (including Callisto) and soybeans. See the Dual II Magnum label for full tank mix details, including weeds controlled, tank mix partners and rates.

Potatoes: Tank-mix with Sencor® 75DF at 0.75-1.5 kg/ha (0.3-0.6 kg/ac) for residual control of annual broadleaf weeds and grasses.*

* Consult the label of the product to be tank-mixed with Dual II Magnum for specific instructions regarding broadleaf weeds, soil type variations, rotational crops, grazing or other restrictions

Nitrogen solutions or complete liquid fertilizers may replace water as a carrier for pre-plant surface, pre-plant incorporated or pre-emergent application of Dual II Magnum alone or in tank mixes in corn. Do not use fertilizer solutions for post-emergent applications. Always predetermine the compatibility of Dual II Magnum or labelled DUAL II Magnum tank mixes with your water or liquid fertilizer carrier by mixing small proportional quantities in advance. Always consult the label of the tank mix partner if tank mixtures are to use liquid fertilizer as the carrier.

Many dry bulk granular fertilizers may be impregnated with Dual II Magnum plus AAtrex® for pre-plant incorporated application to control weeds in corn. Consult the label for more details.

Technical Information

Chemistry Group

Group 15 Herbicide; Active Ingredient: S-Metolachlor

Mode of Action

Dual II Magnum contains a proven active weed control ingredient - S-Metolachlor - to ensure optimum effectiveness across a broad range of weeds. Dual II Magnum is taken up by the shoots of the plants. In grasses and yellow nutsedge, the shoots are the primary site of uptake. The active ingredient, S-Metolachlor, effectively inhibits weed growth by translocating to the weed's growth points and restricting shoot and root development. With S-Metolachlor weeds fail to emerge, weed seedlings are deformed, they suffer from trapped leaves, or leaves emerge underground. So your corn doesn't have to compete during the crucial early stages of growth.

No resistance
The S-Metolachlor in Dual II Magnum is a multi-site Group 15 herbicide and no resistance to it has ever been reported anywhere in the world. Due to its unique mode of action and multiple uptake sites within the weed plant, resistance to Dual II Magnum is highly unlikely to occur.

An active ingredient to ensure crop safety, too
Benoxacor, the added safener found in Dual II Magnum, increases the corn plant's natural GST enzyme level by a factor of five, making the plant able to quickly break down S-Metolachlor and eliminate any chance of herbicides stress.

CHOOSE A TOUR to view more information about S-Metolachlor and Benoxacor
S-Metolachlor Development - Flash
S-Metolachlor Development - HTML

Benoxacor Technical Info. - Flash
Benoxacor Technical Info. - HTML

Labels & MSDS

Label Download
Description Emulsifiable concentrate for selective weed control in a number of crops.
Active ingredient S-Metolachlor and R-enantiomer
Provinces (for sale and use in) AB, BC, MB, NB, NF, NS, ON, PE, QC, SK
Crops (for sale and use in) Asparagus, Beans, black (dry), Beans, cranberry, Beans, green snap (common), Beans, Kidney, Beans, kidney (dry), Beans, lima, Beans, pinto (dry), Beans, white (dry), Beans, yellow snap (common), Blueberries, highbush, Broccoli, Cabbage, Cantaloupes, Carrots, Cauliflower, Celery, Christmas trees, Conifers, Corn, seed, Corn, silage, Corn, sweet, Cucumber, Cucurbit vegetables, Edamame, Eggplant, Fruit trees (bearing), Fruit trees (non-bearing), Jack Pine, Millet, pearl, Mustard greens, Norway spruce, Ornamental, Herbaceous, Ornamentals, Outdoors, Ornamentals, woody, Parsnip, Peanuts, Peas (grown for processing), Peppers, Peppers, bell, Poplar, Potatoes, Potatoes, sweet, Pumpkins, Radish, oriental, Red pine, Rutabagas, Soybeans, Soybeans (conventional), Spruce, black, Squash, winter, Stoolbeds (second-year or older), Strawberries, Sugar Beets, Sweet White Lupins, Tomatoes, Tomatoes (transplanted), White Pine, White Spruce
SDS Download

Disclaimer – ALWAYS read and follow label directions. Please use this information above only as a guideline and not an exact description.

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