General Information


Primo MAXX for turf growth management reduces the frequency of mowing and the amount of grass clippings by reducing the vertical growth of warm- and cool-season turfgrasses. Other benefits, such as increased turf density, increased color, and increased turf quality, are frequently observed after Primo MAXX applications.

Primo MAXX can be applied to well-maintained, quality turfgrass areas, such as residential and commercial lawns, golf courses, sod farms, sports fields, cemeteries, and similar areas. Primo MAXX is useful in the management of difficult-to-mow areas and can be used to minimize the need for edging turfgrass along sidewalks, curbs, parking lots, driveways, flower beds, fences and around posts, storage sheds, and trees.

Turf Pre-Stress Conditioning

Multiple Primo MAXX applications along with cultural practices such as fertilization, irrigation, drainage, mowing height, etc., will delay the onset of stress, improve stressed turfgrass survival, and enhance turf’s recovery from stress.

Apply Primo MAXX to healthy, actively growing turf before the onset of stress and continue to apply Primo MAXX throughout the growing season as long as the turf remains healthy.

Turfgrass root-mass is often greater in Primo MAXX treated turf than in similar, untreated turf. As turf top growth slows, energy is redirected to below-ground plant parts, and root and rhizome production increases. Research has demonstrated that Primo MAXX may also enhance the performance of fungicides. Monthly applications of Primo MAXX at the label rate or more frequent applications at lower label rates strengthen the turfgrass to help it resist disease. In addition, if mowing is less frequent, and leaf material removal is reduced, contact and systemic products stay at effective concentrations on or in the turf longer.

Multiple applications of Primo MAXX will reduce water use and improve drought tolerance. Primo MAXX applications result in smaller, more compact turfgrass, and leaf area is reduced for transpiration. Increased turf density reduces moisture loss from soil evaporation, and additional soil moisture is available due to increased root depth and mass. Primo MAXX may increase carbohydrate levels which have been shown to enhance heat and cold tolerance.

Repeat applications will improve turf quality in areas of reduced light intensity when applications begin while the turf is still healthy.

Primo MAXX reaches the growing point by foliar uptake and is rainfast from rainfall or irrigation after one hour.

Watering-in is not necessary for activation.

The rates presented in the Application Rate Table in the label provide approximately 50% growth inhibition over a 4-week period with little or no discoloration of turf growing under favorable conditions.

NOTICE TO USER: Plant tolerances to Primo MAXX have been found to be acceptable for the grasses listed on the label. Due to the large number of species and cultivars of grasses, it is impossible to test every one for tolerance to Primo MAXX. Neither the manufacturer nor the seller has determined whether or not Primo MAXX can be used safely on grasses not specified on the label. The professional user should determine if Primo MAXX can be used safely prior to commercial use. Before using Primo MAXX for grasses not listed in the application table, test Primo MAXX on a small scale first. Apply the lower rate for the turf setting (lawn, fairway, etc.) and evaluate for phytotoxicity and growth inhibition to widespread use.


(1) Areas treated with Primo MAXX should continue to receive regular maintenance practices, including irrigation; fertilization; and weed, disease, and insect control when necessary, and as recommended for quality turf. Because some herbicides can injure turf, tank mixes with Primo MAXX should be tested on a small scale before widespread use.

(2) Primo MAXX may cause temporary yellowing. This usually disappears about one week after application. To minimize yellowing and to enhance the green color of turf, apply readily available nitrogen at 0.2-0.5 lb. of actual nitrogen per 1,000 sq. ft. If desirable, rates of iron per 1,000 sq. ft. can also be used. (3) Full growth regulation by Primo MAXX begins at about 3-5 days after application.


Applications of Primo MAXX can be made as frequently as weekly during the growing season, however, DO NOT exceed a total of 7.0 fl. oz./1,000 sq. ft. (305 fl. oz./A; 19.0 pt./A) per year.

The rates presented in the Application Rate Table in the label provide approximately 50% growth inhibition over a 4-week period with little or no discoloration of turf growing under favorable conditions. If applications of Primo MAXX are made on a weekly or biweekly basis, reduce the lowest rate in the table by at least 50% for the first application and monitor the turf growth to adjust application rate for the desired growth suppression.

Application Equipment

Primo MAXX may be applied with backpack sprayers, hand sprayers, boom sprayers, and with spray gun application devices.

Application Timing

Apply Primo MAXX to actively growing turf. If turf is going into dormancy because of high or low temperatures or lack of moisture, apply a lower rate of Primo MAXX.

Repeat applications of Primo MAXX may be made as soon as the turf resumes growth or more suppression is desired.

Environmental conditions, management, and cultural practices that affect turf growth and vigor will influence the response of the turf to Primo MAXX applications. Fertility level, moisture availability, plant vigor, height, and frequency of mowing, etc. have been shown to influence the activity of Primo MAXX.


Generally, Primo MAXX provides more suppression when turfgrasses are maintained at lower mowing heights than higher mowing heights. Application rates have been selected for typical mowing heights. The application rate may need to be adjusted depending on actual mowing conditions. To minimize possible turf injury, apply Primo MAXX, then wait at least 4 hours before mowing or mow first, wait at least 1 hour, then apply Primo MAXX.

Excessive turf growth, which may occur with high fertilization or during spring flushes, may require higher rates of Primo MAXX. Under these conditions, Primo MAXX rates may need to be increased up to 50% to provide an adequate length of control.

For extended growth suppression, when temporary discoloration can be tolerated, a maximum of twice the Primo MAXX rate from the Application Rate Table in the label may be applied.

Primo MAXX use rates may need to be reduced up to 50% for turfgrass grown under conditions of low fertility, compaction, or other factors which stress the turf.

Refer in the label regarding tank mix information.

Limitations, Restrictions, and Exceptions


- The rates should provide 50% suppression of turf growth under good growing conditions for 4 weeks with minimal yellowing.

- Seedheads: At rates equal to or higher than the rates given, Primo MAXX provides seedhead suppression of hybrid bermudagrass, and partial seedhead suppression of annual bluegrass, bahiagrass, buffalograss, carpetgrass, common bermudagrass, Kentucky bluegrass, and tall fescue. Primo MAXX must be applied prior to seedhead formation. Do not apply more than 7.0 fl. oz./1,000 sq. ft. per year.