PGR, disease and insect control strategies to reduce stress

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

As we transition into summer, it’s time to start thinking about strategies for combating turfgrass pests. While certain pests like crabgrass, white grubs and summer patch generally require preventive applications in the spring, other pests like dollar spot, black cutworms and dandelions can be managed at first observance. However, there are times during the season when environmental conditions are favorable for pest development and impart stress on turfgrass plants. This reduces their ability to defend themselves and recover, further increasing pressure on plant protectants to perform.
Prepare for the season ahead by following an agronomic program, which will help provide season-long management of pressures in your region.


During periods of high pest pressure, the normal methods of control or management tend to be less effective, shorter in duration and sometimes fail to work. These are typical outcomes when addressing high pest populations with a predetermined management program. Consider adjusting your program for allowances during such periods and take into account the cultural practices necessary to facilitate turfgrass growth and recovery.

#PrimoTurns30: proven protection for three decades 

For three decades, Syngenta has helped superintendents maintain healthier turf with Primo plant growth regulator (PGR). The current formulation, Primo Maxx® PGR, helps superintendents through pre-stress conditioning programs that prepare turf to withstand ongoing stressors including heat, drought and disease, improving turf quality, playability and wear tolerance throughout the season.  

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

Disease control strategies
  • Get an accurate diagnosis of the problem
  • Employ cultural practices to lessen symptoms (e.g., irrigate or hand water as needed)
  • Reduce plant stress to enhance recovery (e.g., increase mowing height or reduce mowing frequency)
  • Shorten application intervals and increase to maximum labeled rate, if applicable
  • Monitor risk of extended disease occurrence for near- and long-term planning (i.e., Smith-Kerns model for dollar spot or soil temperature alerts for preventive fungicide application for soil borne diseases, such as summer patch)
  • Re-evaluate your program to prevent future episodes (find agronomic program examples here

Weed control/PGR strategies
  • Avoid treating weeds or turfgrasses that are under environmental stress
  • Adhere to label recommendations for temperature restrictions and tank-mixing partners
  • Avoid maximum label rates if there is risk for turf injury, or consider spot-treatment applications if turf tolerance is questionable 
  • Ensure weeds are not above recommended growth stages for treatment, or determine if they could be controlled with a pre-emergent herbicide next season (i.e., soil temperature alerts for timing crabgrass prevention)
  • Wait for favorable conditions to return and weeds are actively growing for best treatment results
  • Monitor growing degree days or turfgrass growth for PGR re-application intervals
  • Reduce PGR rates and lengthen intervals under extreme environmental stress conditions
Looking for post-emergent weed control solutions? Read more about the enhanced label from Manuscript® herbicide or post-emergent control in fine fescue with Fusilade® II herbicide

Insect control strategies
  • Scout, identify and monitor insect populations for treatment thresholds
  • Understand the life cycle and target development stage of the insect for maximum effectiveness (i.e., early instar white grubs are easier to control than late instars)
  • Higher rates and subsequent applications may be needed for insects that are mobile or have multiple generations
  • Monitor treated areas and assess damage and application efficacy
  • Follow individual label instructions for post-application irrigation

For more information about managing pest pressures, sign up for agronomic alerts when conditions hit target thresholds in your area or contact your local Syngenta territory manager.

© 2023 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. Fusilade®, GreenCast®, Manuscript®, Primo Maxx®, WeevilTrak℠ and the Syngenta logo are trademarks or service marks of a Syngenta Group Company. All other trademarks are the property of their respective third-party owners.  

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