Prime Source Trin Pac Select Plant Growth Regulator

5 out of 5 stars 1 Reviews | 3 Q&A

Prime Source Trin Pac Select Plant Growth Regulator

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5 out of 5 stars Rating: 5

1 Review | 3 Q&A

Product Overview

Prime Source Trin Pac Select is a plant growth regulator (PGR) that slows the top growth of the plant. By limiting the vertical growth, the energy in the plant is redirected to strengthening the root structure as well as prompting greater lateral growth. Using Trin-Pac Select will result in a reduction in the frequency of mowing and the amount of grass clippings, while increasing the color, quality and density of the turf. Trin-Pac Select PGR is rainfast within one hour after application and is effective only through absorption and not by plant uptake through the soil. As such, the use of a “spreader” such as Ultra Spread Select may be beneficial.

  • Reduce turf maintenance costs
  • Increase the color, quality and density of turf
  • Reduce turf growth by 50% for up to four weeks
  • Formulation is odorless and mixes easily
  • Better drought resistance and stress recovery
  • Rainfast within 1 hour after application
  • Can be used to extend the life of turf-marking paint

The plant growth regulator contains Trinexapac-ethyl as its active ingredient and it works through foliar absorption to effectively improve stress tolerance of turf edging. If directions for turf growth management were followed accordingly, it will minimize the frequency of mowing and the amount of grass clippings produced by mowing. It can be used on lawns, sod farms, golf courses, sports fields, cemeteries, and difficult to mow areas. This is also available in a 2.5 gallon size.

Trin Pac Select is comparable to Primo Maxx plant growth regulator.

Features and Specs

Active Ingredient Trinexapac-ethyl 11.3%
Target pests Cool & Warm-Season Turf-grass
For use in Residential and Commercial Lawns, Golf Courses, Sod Farms, Sports Fields, Cemeteries and difficult to mow areas
Application * See label for complete application instructions
Pet safe Yes, is used as directed on label (Hazards to humans and domestic animals)
NY (Restricted To Licensed Applicators Only)
Special Features Reduces the growth of Cool and Warm-Season grasses as well as increase the quality, color, and density of turf
Shipping Weight 9.37 lbs
Manufacturer Prime Source
EPA Registration 89442-7




For greater suppression with Trin-Pac Select, maintain turfgrass at lower mowing heights. Note that the rates given in the application rate table are for turf at typical mowing heights; therefore, the application rates should be adjusted based on the grass height at application. The lower the height of cut of the particular turfgrass species, the less material is required to provide the desired turf growth regulator effect.

Turfgrass injury can be minimized by using one of the following options:

  1. Mow 4 hours after the application of Trin-Pac Select; OR
  2. Mow 1 hour before application of Trin-Pac Select equipment.

Trin-Pac Select may be applied using one of the following types of spray equipment:

  • backpack sprayers
  • hand sprayers
  • boom sprayers
  • spray gun application devices

Use only spray equipment that has been thoroughly cleaned before use. Ensure that the sprayer will deliver an accurate and uniform spray by calibration of the equipment. After use, clean the spray with clean water and dispose of rinsate according to label directions.

Mixing Instructions

  1. Add Trin-Pac Select to a sufficient amount of water (ex., 0.5 to 4.0 gallons of water per 1,000 sq. ft.).
  2. Mix only the volume of spray mixture required for the square footage to be treated.
  3. Ensure adequate agitation during application.
  4. When Trin-Pac Select is used as a tank mix with other products, agitation is required.
  5. Apply Trin-Pac Select in a uniform manner to ensure thorough coverage of the crop.

For tank mixes, use only if the mixing partner is registered for this use. Do not mix Trin-Pac Select with any product which prohibits such mixing. Do not exceed any label application rate and follow the most restrictive label precautions and limitations. Refer to the tank mix partner label(s) for further information.

Backpack and hand Sprayers (0.5 to 4.0 gallon capacities)

Trin-Pac Select Alone: Fill the spray tank with total amount of water required. Add the appropriate amount of Trin-Pac Select. Close the spray tank and agitate to ensure a uniform solution. Make spray applications to turfgrass.

Boom and hand-gun Sprayers

Trin-Pac Select plus Tank Mixtures: Before mixing Trin-Pac Select with other components, determine the compatibility of the tank mix using the Tank Mix Compatibility Test below. Once the compatibility of the mixture is assured, add the products (such as carrier or other pesticide products) to the spray tank in the order noted below:

  1. Add 1/2 of the required amount of water to the spray tank.
  2. Keep the tank mix agitated to ensure formation of a uniform suspension.
  3. Add any products that are packaged in water-soluble bags first. Keep the tank mix agitated to ensure that the water-soluble bags dissolve and the contents dispersed in the tank mix. Continue agitation and then add water-dispersible granules (WG), followed by wettable powders (WP). Before adding other products, ensure complete dispersal of the solid products.
  4. Add emulsifiable concentrates (EC).
  5. Add flowable liquids (FL) or suspension concentrates (SC).
  6. Add Trin-Pac Select.
  7. Add spray adjuvant and spray markers. Use surfactants approved for application to turf. Check surfactant label before use.
  8. Add the remainder of the water.
  9. Agitate tank mix combinations. Do not let mixtures sit in the spray tank without agitation. Only prepare the amount of spray mix required for use on one day and apply it all that day.

Tank mix compatibility test

Add relative proportionate amounts of Trin-Pac Select, other products to be used, and the water in a clear glass quart jar with a lid. Close the lid and invert the jar several times and observe the mixture for approximately 30 minutes. The mixture is not compatible if the following is observed: formation of balls, flakes, sludge’s, gels, oily films or layers; or precipitates.

Application near and Around Monuments and hardscape Materials.

Brass, bronze, concrete, marble, granite, or other types of stone are not stained by Trin-Pac Select when applied at normal dilution rates.

To ensure Trin-Pac Select will not stain other materials, test Trin-Pac Select on a small-scale basis before using on a larger scale.

Pre-Stress conditioning of Turfgrass

To delay the onset of stress, improve turf survival under stress, and enhance the turf’s recovery from stress, make multiple applications of Trin-Pac Select. Normal turf cultural practices such as fertilization, irrigation, drainage, mowing height, etc., should be maintained.

Trin-Pac select can be applied to healthy, actively growing turf before the onset of stress and may continue to be applied through the growing season as long as the turf remains healthy. Do not apply more than 7.0 fl. oz. Per 1,000 sq. ft. per year.

Application of Trin-Pac Select may produce turfgrass root-mass which is often greater in treated turf than in similar untreated turf. This increase in turfgrass root-mass is a result of the reduction in turf top growth, thereby redirecting the energy to below-ground plant parts and increasing production of the root and rhizome system.

Enhanced fungicide performance has been demonstrated in research trials when monthly applications of Trin-Pac Select at the label rate or biweekly applications at 1/2 the label rate was shown to strengthen the turfgrass and to help it resist disease. Since mowing is less frequent and removal of leaf material is reduced, contact and systemic fungicide products remain more effective in or on the turf longer.

Multiple applications of Trin-Pac Select will result in smaller, more compact turfgrass and reduced leaf area. This causes a reduction in transpiration and water use and improves drought tolerance of the turfgrass. Loss of moisture from soil evaporation is reduced by the increased turf density allowing soil moisture to be available due to increased root depth and mass. Trin-Pac Select also may increase carbohydrate levels in turfgrass; increased carbohydrate levels have been shown to enhance heat and cold tolerance of turfgrass.

Suppression of Anthracnose

Trin-Pac Select can be applied at rates of 0.1 to 0.2 fl. oz. Per 1,000 sq. ft. every 7 to 14 days to suppress basal rot anthracnose. Use the lower rate when seedheads are present. For optimal disease control, tank mix with other fungicides registered for the control of anthracnose.

Poa Annua conversion/Renovation

When overseeding or renovating existing turf infested with strands of Poa annua, Trin-Pac Select use allows better germination and seedling growth of the more desirable turf, results in fewer clippings, and thus reduces maintenance traffic on new seedlings. Trin-Pac Select is foliarly-absorbed; therefore, it does not affect seed germination. Trin-Pac Select should be applied 1 to 5 days before seeding and before verticutting, scalping, spiking, or other similar operations.

Temporary initial discoloration of turfgrass infested with Poa annua is possible with aggressive application rates of Trin-Pac Select. In the subsequent spring season, apply Trin-Pac Select at the higher rate for the turf type and setting listed in the Application Rate Table.

As described above, the success of this treatment will also depend on other factors such as growing conditions, fertilization, rainfall, and other agronomic and environmental conditions.

Bermuda grass overseeding

In addition to normal turfgrass cultural practices, Trin-Pac Select applications to Bermuda grass enhance the establishment of cool-season Turfgrasses, help ensure new seedling vigor and growth and will result in fewer clippings and less maintenance traffic on new seedlings. Since Trin-Pac Select is foliarly absorbed, germination and seedling growth is unaffected by Trin-Pac Select.

Apply Trin-Pac Select 1 to 5 days before seeding and before verticutting, scalping, spiking, or other similar operations to the Bermuda grass.

Aggressive application rates of Trin-Pac Select may cause temporary initial discoloration of turfgrass. To avoid discoloration, use the normal seeding rates for your area and turf setting (lawn, fairway, etc.). The success of overseeding will depend on a number of factors including growing conditions, fertilization, rainfall, and other agronomic and environmental conditions. See the Application Rate Table for maintenance application rates.

Applications with Turf-Marking Paint

The duration of marking paint on turf can be extended when Trin-Pac Select is applied before or with the marking agents. When used with latex-based marking agents, mix Trin-Pac Select with water before adding the marking agent. For further directions, read the product label or the marking agent and the Trin-Pac Select + tank mixtures section of this label.

Use Rate: 1 ounce of Trin-Pac Select in 1 gallon of marking paint treats approximately 1,000 sq. ft. of line surface area.

Plant Tolerance

The grasses listed on the label have been shown to be tolerant of Trin-Pac Select. It is impossible to test every species and cultivars of grasses for tolerance to Trin-Pac Select. Before commercial use, the professional user should determine if Trin-Pac Select can be used safely on grasses not listed in the Application Rate Table by conducting small-scale tests. The lower rate for turf setting (lawn, fairway, etc.) should be tested and evaluated for phytotoxicity and growth inhibition prior to use on a large scale.

Application Rates and Timing

Apply Trin-Pac Select to actively growing turf. Use the lower rate of Trin-Pac Select in situations when turf is going dormant due to high or low temperatures, or to lack of moisture.

Make repeat application(s) of Trin-Pac Select as soon as the turf resumes growth or if more suppression is desired. Do not apply more than 7.0 fl. oz. per 1,000 sq. ft. per year.

The Application Rate Table provides use rates that lead to approximately 50% growth inhibition over a 4-week period and produce little or no discoloration of turf when turf is growing under favorable conditions.

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  • 5 of 5 Stars

    It Works Very Nicely!!

    By Garry on 04/19/2020

    I sprayed this on my Bermuda about a month ago, and I haven't had to cut my grass but once since then. My grass looks lush and green as well. Ensure that you don't put this stuff down if you have recently laid seed, however, because the seed will not germinate. EXCELLENT PRODUCT!!

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Questions & Answers

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What is the shelf life before and after the seal is removed?
The shelf life of Select Source Trin Pac is 3-5 years before and after the seal has been removed. It should be kept out of extreme temperatures, which are below 35 degrees Fahrenheit and anything above 90 degrees Fahrenheit.

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5 of 5 people found this answer helpful

What is application rate of Prime Source Trin Pac Select Plant Growth Regulator? How much lawn will 1 gallon treat?

The Prime Source Trin Pac Select Plant Growth Regulator has a varying range of use rates based on the grass type you would be applying it to. You would need to reference the charts on the Product Label to find your grass type and see how much you would need per 1000 sq/ft per application. 

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Can Prime Source Trin Pac Select Plant Growth Regulator be used on Zoysia grass?

Prime Source Trin Pac Select Plant Growth Regulator is not labeled for use on zoysia. We do not recommend using this product because it may damage your turf. 

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