• After a very favorable spring for cool season turf, we have found ourselves suddenly on the opposite end of the condition spectrum with an expected seven to ten day stretch of temperatures in the upper nineties, approaching the triple digits and little to no rain. We will be shifting from little to no irrigation need to a need beyond what irrigation can fully fulfill. Soil moisture levels are still quite favorable which will help us as we move into this pattern.  We have already taken or are in the process of taking steps to increase watering levels to try and counteract these conditions, but this only goes so far. Inspections of systems continue to insure we are operating in good condition. We should expect to see areas of cool season turf stress during this period, regardless of irrigation depending on exposure, soil conditions, root depth, and overall health of the turf. 

  Conditions are also favorable for disease with high overnight temperatures and humidity levels. 

  A few helpful points are provided below.

    

• • Soil temperature at 4” depth and its effects on cool season turf. These explain why it is impossible to keep cool season turf lush and thriving in peak summer conditions. This is regardless of being able to replenish ET losses. When we consider the biology, we know that peak summer conditions are when to expect the turf to look its worst. It typically will not die but go into dormancy to protect itself, until conditions improve.
•  
• • 90 F – shoot growth ceases
  • 77 F – root growth ceases
  • 60-75 F – optimum for shoot growth
  • 50-65 F – optimum for root growth         

   

  • Losses of water due to environmental conditions (weather) and turf respiration (life cycle) are typically 0.25” – 0.30” per day in these peak conditions. It is nearly impossible to replenish this total amount of loss with irrigation. Irrigation systems are only about sixty to seventy percent efficient meaning to apply 1” worth of water, thirty or forty percent more water is required to be used to reach that 1” applied. We also must consider water source limitations where a complete watering of a site or community cannot be completed in one night and watering throughout the daylight period is not desirable.

   

Once conditions moderate to more average summer conditions, we will see improvement in turf conditions.

Those sites with warm season turf types (Bermuda / Zoysia)  will be thriving in these conditions.