Princep Liquid (Simazine 4L)

Princep Liquid, manufactured by Syngenta, was formerly called Simazine 4L is a pre-emergent herbicide that controls many different common weeds like Poa Annua, Ragweed, Crabgrass, and over 40 other broadleaf and annual grassy weeds.

This product will control weeds before they emerge, but will not kill weeds that have already emerged. Princep can even be used in crop fields to protect your plants from weeds.

Tools Needed:

To use Princep Liquid, you will need spraying equipment. For a small volume application, you can use a pump sprayer, a backpack sprayer or a hose-end sprayer. For large volume application, you can apply using a professional skid sprayer.

How to Use:

• Step 1: Figure out how much Princep Liquid you will need by calculating the size of the treatment area. To do this, measure and multiply the area's length x width to get the total square footage to be treated. Princep Liquid treatments should be applied at a rate of 0.75 to 1.5 fl. oz. in a gallon of water per 1,000 sq. ft. on turfgrass. For large volume applications, apply 1 to 2 quarts of Princep Liquid per 20 gallons of water per acre. For example, if you measured 3,500 sq. ft. of area to be treated you will need to mix between 2.62 to 5.25 fl. oz. of Princep in at least 3.5 gallons of water.
• Step 2: Fill your sprayer halfway with water. Measure the required amount of product and add it to the sprayer. Fill your sprayer with the rest of the water and thoroughly agitate it and you’re ready to apply.
• Step 3: Apply the product over the desired area, preferably on a fan spray setting for uniform coverage. Reapply as needed, following label instructions regarding your application type.

Where to Use:

Princep can be applied on residential and commercial lawns and common plant growing areas like nurseries, crop fields and more. Refer to the label for a full list of applicable locations.

When to Use:

Princep Liquid is typically applied in late fall before the regular rains to prevent weed germination. Princep is most commonly used as a soil application over plants that are already established, so it may not be the best option for plants that are still young. Refer to the label for proper application timings, as they can vary depending on the climate, targeted weed, and application method.

Safety Information:

Princep is safe to use around children and pets when applied according to the product label instructions. Always wear the proper personal protective equipment (PPE) when mixing and applying this product.

Wait until 48 hours have passed after application before allowing children, pets, and workers to enter treated areas. 

It is important to prevent any drift of this product from getting into non-target areas, as it can contaminate water or harm non-target plants.

Special Considerations:

It is recommended not to apply Princep Liquid to sand and loamy sand soils because the active ingredient Simazine can travel or leach through soil and can enter groundwater.