By Matt Giese, M.S., technical services manager, Syngenta

90% of surveyed golf course superintendents are confident that Primo Maxx^® plant growth regulator (PGR) delivers leading PGR performance with a 4.54 star rating (out of 5).¹ 

Top uses of Primo Maxx by superintendents surveyed include:

• Enjoy fewer clippings
• Improve turf quality/color
• Savings of fuel/labor
• Minimize scalping
• Suppress Poa annua seedheads
• Improve drought tolerance
• Enhance fungicide performance
• Improve shade tolerance

Improved turf quality

Preconditioning can prepare your turf for extreme conditions before they develop during the summer. A PGR like Primo Maxx can help you improve turf quality and prepare for harsh conditions in diverse growing environments. A single green—or whole golf course—can be impacted by micro-environments like:

• Full sun
• Partial shade 
• Inefficient irrigation coverage
• Foot traffic patterns

Primo Maxx improves turf consistency in all types of conditions by strengthening plants to withstand and recover better from those biotic and abiotic stresses. These attributes weren’t developed overnight—the benefits of Primo Maxx are backed by research.

Suppressing seedheads

As part of a management program, Primo Maxx can be tank mixed with Proxy^® PGR to promote Poa annua seedhead suppression and improved turfgrass quality in existing turfgrass stands. Applications should be timed several weeks prior to seedhead emergence and may require follow-up applications for best results. See individual specimen labels for use information and restrictions.

Tank mixing PGRs

Turfgrass species respond differently to different PGRs and using them together in the same tank can offer consistency and more even growth suppression over time. For added growth regulation longevity, consider tank mixing Primo Maxx with Trimmit^® 2SC PGR in cool-season species. Mixing Primo Maxx and other PGRs offers the ultimate flexibility to customize a PGR program to your specifications. View rates and recommendations for tank mixing Primo Maxx and Trimmit, and view the Primo Maxx + Trimmit Multipak, which includes both PGRs in one convenient package configuration for 15% savings.

Enhancing disease control

Did you know that Primo Maxx is labeled for suppression of basal rot anthracnose? A tank-mix of Primo Maxx, Daconil^® Action™ fungicide and Appear^® II fungicide provides improved disease control and turf quality. Consider improving your fungicide effectiveness by incorporating Primo Maxx in your agronomic program or see examples here.

Improving drought tolerance

Maintain healthier turf by implementing a pre-stress conditioning program with Primo Maxx. It prepares turf to withstand ongoing stressors including heat, drought and disease, thus improving turf quality, playability and wear tolerance throughout the season. Primo Maxx works by slowing the production of gibberellic acid, a plant hormone that promotes cell elongation. This causes vertical shoot growth to slow while lateral and below-ground growth of rhizomes, stolons, tillers and roots increases.

Multiple applications of Primo Maxx will help reduce water use and improve drought tolerance, potentially providing irrigation system efficiencies through water and electricity cost savings.

McCann and Huang, "Effects of Trinexapac-Ethyl Foliar Application on Creeping Bentgrass Responses to Combined Drought and Heat Stress."

Extensive research has proven the effects of preconditioning with Primo Maxx and subsequent heat and drought stress. A study conducted by Dr. Bingru Huang and Steve McCann at Rutgers University found preconditioning plants with Primo Maxx was beneficial for plant survival during extended periods of combined drought and heat stress.

Recommendations for application​​​​​​​

Primo Maxx should be applied to healthy, actively growing turf before the onset of stress. Alongside cultural practices such as proper management of fertilization, irrigation, drainage and optimum mowing height, Primo Maxx can be applied throughout the growing season as long as the turf remains healthy. Application rates depend on the species of turf and its height of cut. Please review the product label and our agronomic program for specific recommendations.

Growing Degree Days (GDDs) are commonly utilized to predict important events in plant development. Knowing your accumulated GDD threshold can help you better manage your application timing, including predicting PGR application intervals.

For more information about Primo Maxx or Trimmit, please contact your local Syngenta territory manager.

¹Source: Survey of 376 golf course superintendents conducted via TechValidate in February, 2023.

Syngenta hereby disclaims any liability for Third Party websites referenced herein.

All photos are either the property of Syngenta or are used with permission.

© 2025 Syngenta. Important: Always read and follow label instructions. Some products may not be registered for sale or use in all states or counties and/or may have state-specific use requirements. Please check with your local extension service to ensure registration and proper use. Action™, Appear^®, Primo Maxx^®, Trimmit^®, the Alliance Frame, the Purpose Icon and the Syngenta logo are trademarks of a Syngenta Group Company. All other trademarks are the property of their respective third-party owners.