General Information


Aerial application is prohibited.

When tank mixing or sequentially applying simazine or products containing simazine, the total pounds of simazine applied must not exceed the specific maximum rate per calendar year as noted in the use directions.

Apply Princep Liquid before weeds emerge or after removal of weed growth. Princep Liquid controls a wide variety of annual broadleaf and grass weeds when used at selective rates in turf and ornamental plantings.

Where a range of application rates is given, use the low rate on coarse-textured soil and soil lower in organic matter; use the high rate on fine-textured soil and soil higher in organic matter.

To avoid spray drift, do not apply under windy conditions. Avoid spray overlap, as crop injury may result.

Since Princep Liquid enters weeds mainly through their roots, moisture is needed to move it into the root zone. Very dry soil conditions following application may necessitate shallow cultivation or rotary hoeing.

Princep Liquid is nonflammable.


Princep Liquid is a Group 5 Herbicide (contains the active ingredient simazine).

Following many years of continuous use of this product and chemically related products, biotypes of some of the weeds listed on the label have been reported which cannot be effectively controlled by this and related herbicides. Where this is known or suspected, and weeds controlled by this product are expected to be present along with resistant biotypes, we recommend the use of this product in registered combinations or in sequence with other registered herbicides which are not triazines, i.e. which are not solely a Group 5 Herbicide. If only resistant biotypes are expected to be present, use a registered herbicide which is not solely a Group 5 Herbicide. Consult with your State Agricultural Extension Service for specific recommendations.


Ground application: Use conventional ground sprayers equipped with nozzles that provide accurate and uniform application. Be certain that nozzles are uniformly spaced and the same size. Calibrate sprayer before use and recalibrate at the start of each season and when changing carriers. Unless otherwise specified, use a minimum of 20 gallons of spray mixture per acre.

Use a pump with capacity to: (1) maintain 35-40 psi at nozzles, (2) provide sufficient agitation in tank to keep mixture in suspension, and (3) to provide a minimum of 20% bypass at all times. Use centrifugal pumps which provide propeller shear action for dispersing and mixing this product. The pump should provide a minimum of 10 gals./minute/100 gal. tank size circulated through a correctly positioned sparger tube or jets.

Use screens to protect the pump and to prevent nozzles from clogging. Screens placed on the suction side of the pump should be 16-mesh or coarser. Do not place a screen in the recirculation line.

Use 50-mesh or coarser screens between the pump and boom, and where required, at the nozzles.

Check nozzle manufacturer’s recommendations.

Refer in the label regarding tank mix information.

Limitations, Restrictions, and Exceptions


St. Augustinegrass, Bermudagrass, Centipedegrass, and Zoysiagrass

Apply 1-2 qt./A of Princep Liquid.

Do not apply to established beds within 2 days after lifting of sod. Do not apply to new beds before 7-10 days after sprigging or plugging.

Do not apply more than 2 lb. a.i./A (2 qt. of Princep Liquid) per application and not more than two applications per calendar year. Do not exceed 3 qt./A Princep Liquid (3 lb. a.i./A) per calendar year.

Precautions: On newly sprigged turfgrass, hybrid bermudagrass, nondormant bermudagrass, or nondormant zoysiagrass, temporary slowing of growth and yellowing may occur following application.

To avoid turf injury, (1) Use only on turfgrass reasonably free of infestations of insects, nematodes, and diseases. (2) Do not use north of NC (except in the VA Coastal Plains) or on soils with a pH above 7.8. (3) Do not use on muck or alkaline soils. (4) Do not apply over the rooting area of trees or ornamentals not listed on the label. (5) Do not seed or overseed with desirable turfgrass within 4 months before or 6 months after treatment. (6) Do not apply this product to newly seeded grasses until they have overwintered and have a well-developed rhizome system. (7) Do not exceed 2 qt./A of Princep Liquid within 12 months of seeding grasses.

Note: Do not graze or feed turf clippings to animals or illegal residues may result.

Restricted Entry Interval

12 hours

Exception: If the product is soil-injected or soil-incorporated, the Worker Protection Standard, under certain circumstances, allows workers to enter the treated area if there will be no contact with anything that has been treated.