Treflan™ EC

Economical, pre-emergent, season-long control of grass and broadleaf weeds.


  • Soil incorporated long-lasting control of many annual grasses and broadleaved weeds.
  • Controls susceptible weeds by killing seedlings as they germinate. It does not control established weeds.
Treflan EC 05 4C logo


Weeds controlled
  • Annual bluegrass
  • Barnyard grass
  • Brome grass
  • Carpetweed
  • Cheat grass
  • Chickweed
  • Crab grass
  • Fall panicum
  • Goose grass
  • Green foxtail
  • Knotweed
  • Lamb’s-quarters*
  • Loose silky bentgrass
  • Pigweed*
  • Purslane
  • Stink grass
  • Yellow foxtail

Weeds Supressed

  • Wild oats

Crops & Crop Rotation

  • Alfalfa establishment
  • Asparagus
  • Black bean
  • Cabbage
  • Carrot
  • Cauliflower
  • Crambe
  • Dry common beans
  • Faba bean
  • Forage kale
  • Forage rape
  • Lima bean
  • Mustard
  • Ornamentals (woody nursery stock, perennials)
  • Pea (field and canning)
  • Rutabaga
  • Snap bean (common)
  • Soybean
  • Stubble turnip (white, for feed only)
  • Sunflower
  • Transplants: tomato, pepper, Brussels sprouts, broccoli, cabbages, cauliflower and strawberry (spring application only)
  • Transplanted shelterbelts
  • Trees: apple, apricot, cherry, peach, plum and pear (first year)


Rates based on soil texture

All crops registered (except for asparagus, peas and lima beans):

  • Light - 1.2 L/ha
  • Medium - 1.7 L/ha
  • Heavy - 2.4 L/ha

Asparagus (established 3 years):

  • Light - 1.2 L/ha
  • Medium - 1.7 L/ha
  • Heavy - 2.4 L/ha

Pea, Lima bean:

  • Light - Not recommended
  • Medium - 1.2 L/ha
  • Heavy - 1.5 L/ha

See product label for additional details

When to Apply

  • See product label for details

Tank Mixes and Mixing Instructions

  • There are many tank mixes registered for Treflan. Check product label and tank-mix partner label for a complete list of crops and application guidelines.


Mixing Instructions

  • Add the recommended amount of Treflan to clean water in the spray tank, and agitate thoroughly.

Grazing & Harvest

  • Application can be made to ground in the fall following harvest or the in spring in preparation for planting or transplanting.
  • Asparagus – Apply to established asparagus in the early spring after ferns are removed but before spear extension from the crowns, or apply after harvest in the late spring or early summer before ferning begins.

Application Guidelines

  • Ground application: Treflan must be applied in at least 100 L of water per hectare; broadcast basis. Use a low-pressure herbicide sprayer that applies the spray uniformly. Be sure to properly calibrate the sprayer before application and check frequently during use to ensure proper calibration and uniform application. Apply Treflan to the soil surface and incorporate in the same operation if possible. Do not delay incorporation more than 24 hours after application.

• Incorporation

–        Treflan needs to be incorporated into your fields twice at cross angles. The first incorporation should be done within 24 hours of application (period to prevent product from photo degrading on the soil surface), or combined with your application operation.

–        Incorporate Treflan with a tandem disc, discer or field cultivator set to work 8 to 10 cm deep. Operate disc implements at 7 to 10 km/h and cultivators at 10 to 13 km/h.

–        Treflan should not be incorporated with a field cultivator when the soil is crusted, lumpy or too wet for good mixing action.

–        Disc-type implements are preferred on stubble to ensure a 10 cm depth of operation.

–        Incorporation with implements set to cut less than 8 cm deep or more than 10 cm deep may result in erratic weed control or crop damage.

–        Rod weeders, harrows, deep tillage cultivators, chisel plows or hoe drills will not properly incorporate Treflan.

  • Aerial application: Not registered for aerial application.

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.