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PrePass™ Flex

All the performance you've come to expect from PrePass. Now with greater flexibility.


  • Flexibility to mix with any glyphosate formulation, at the rate you choose.
  • Advanced dry formulation that disperses quickly and completely for easy mixing.
    • When mixed with glyphosate there are no mixing precautions or extra surfactants or additives required.
  • Convenient and compact packaging – 640 acre case consists of 8 x 80 acre jugs.
    • No heated storage required.
    • Reduces required storage space and logistics.
  • All the performance you have come to expect from PrePass™.
    • SoilActive™ Technology for extended control of broadleaf weeds for 21 days after application.
    • Time management. Get the work done earlier – spring or fall.


Apply PrePass anytime from harvest until freeze-up for superior control of broadleaf weeds and winter annuals, including: volunteer canola, dandelion, narrow-leaved hawk’s-beard, cleavers, buckwheat, chickweed, stinkweed and more. You’ll get 21 days of SoilActive control – starting this fall, and lasting into next spring.


Cold soil conditions in the fall slow down and eventually stop the breakdown of the SoilActive component in PrePass. As soil warms up again in the spring, PrePass re-activates to begin controlling susceptible weeds again. Fields in which PrePass is applied in late September or October can stay clear of broadleaf weeds through April and even May – allowing you to seed earlier into clean fields

Prepass Flex logo


PrePass FLEX + Glyphosate

Weeds controlled

Broadleaf Weeds

  • Annual Sow thistle1
  • Canada fleabane
  • Canola (all varieties)
  • Chickweed
  • Cleavers
  • Flixweed
  • Hemp-nettle
  • Kochia
  • Lady’s thumb
  • Lamb’s quarters
  • Narrow-leaved hawk’s beard
  • Ragweed
  • Redroot pigweed
  • Russian thistle
  • Scentless chamomile
  • Shepard’s purse
  • Toadflax1
  • Volunteer flax
  • Wild buckwheat
  • Wild mustard

Grass Weeds

  • Downy brome
  • Foxtail barley1
  • Giant foxtail
  • Green foxtail
  • Persian darnel
  • Volunteer barley
  • Volunteer wheat
  • Wild oats

Perennial Weeds

  • Dandelion2
  • Perennial sow thistle1
  • Quack grass1
  • Canada thistle1

1With elevated rates of glyphosate. Refer to glyphosate label for rates
2Seeding, overwintered rosettes, mature plants up to 30 cm in diameter.

Winter Wheat


Winter annual weeds like narrow-leaved hawk’s-beard, flixweed, cleavers and shepherd’s-purse are hard to control in the spring with glyphosate alone, because they are too big. A fall PrePass application is the best way to control these winter annual weeds.

Winter Wheat Info Graphic

Crops & Crop Rotation

Crop Rotation

Fields previously treated with PrePass FLEX Herbicide can be seeded the following year to barley, canola, chickpeas, corn, field beans, flax, Juncea canola, lentils, mustard (brown, oriental and/or yellow), oats, peas, potatoes (except seed potatoes), soybeans, sunflower, wheat, or fields can be summerfallowed.


  • 8 x 0.648 kg jugs in one case
  • 640 acres/case
  • Each jug within the case treats 80 acres
  • Water volume: Ground 20-40 litres/acre (5-10 US gallons/acre)

When to Apply

  • Spring
    • Prior to seeding
    • No later than 48 hours after seeding
  • Fall
    • From late September to freeze-up (after October 1 in southern regions)


  • 30 minutes
  • VP480™ and Roundup WeatherMAX™ are rainfast in 30 minutes. Consult other glyphosate rainfast labelling.

Tank Mixes and Mixing Instructions

Tank Mixes
  • Mixable with all glyphosate formulations (present as isopropylamine salt, diammonium Salt, trimethylsulfonium salt, potassium salt, or dimethylamine salt).
  • Disperses quickly and completely for easy mixing.
  • When mixed with glyphosate there is no need for extra surfactants or additives.
Mixing Instructions
  1. Fill Sprayer tank ½ full of water.
  2. Start sprayer tank agitation.
  3. Add the required amount of PrePass™ FLEX herbicide, continue agitation.
  4. Add the required amount of glyphosate, continue agitation.
  5. Fill the sprayer tank with sufficient water to spray 20-40 litres/acre (5-10 US gallons/acre).

Performance Inquiry Guidelines

Dow AgroSciences encourages contact within the timelines listed for proper field assessments to resolve and rectify the call.

After these deadlines, it is difficult to determine the circumstances leading to non-performance.

  Days After Use
Seed Within 21 days (after crop emergence)
Pre-emergent herbicides Within 21 days (after crop emergence)
Post emergent herbicides Within 21 days after treatment
Pre-seed herbicides Within 21 days after treatment
Pre-harvest or post harvest Within 21 days after seeding – the following spring
Fallow applications Within 21 days after treatment
Fungicides 7 days after treatment
Insecticides 7 days after treatment

* Check Strips: while not essential, a check strip provides a good indication of product performance.