"The current 10-day forecast for the area has highs in the 90’s or 100’s and lows in the 70’s, which is tough on all coolseason grasses. The good news is that cool-season grasses are usually healthy enough to withstand high temperature like this in June, but the bad news is that this heat may weaken the plant leading to thinning or death later this summer. High temperatures cause problems both above and below ground. Above ground, photosynthesis or energy production of cool-season turfgrasses starts to decline once daytime air temperatures exceed 70-75F. At the same time, respiration (the energy-consuming process to maintain the plant) is increasing with higher temperatures. At air temperatures greater than 80-85F, cool-season turfgrass plants are in an energy debit where energy demand is higher than energy production. Short periods of an energy debit are normal and the plant uses stored energy to meet its needs. However, energy stores are depleted with extended heat, and the plant weakens. This energy depletion is further exaggerated during warm nights when the plant uses up far more stored energy for respiration than during cool nights. Since the energy reserves of cool-season plants are fairly high early in the summer (June), they are usually capable of withstanding early summer heat like we are expecting. However, this early summer heat depletes energy reserves that may be needed later in the summer.
Below ground, root growth of cool-season turfgrass is optimal between 50 and 65F and declines quickly above 70F. At the same time, root death increases at elevated temperatures, especially in wet soils with limited ability to hold oxygen. The end result is that root systems become shallow and spindly with prolonged heat and thus have limited ability to take up water and nutrients."
-Zac Reicher, Professor, Turfgrass Science, University of Nebraska-Lincoln; "Forecast heat hard on cool-season grasses," June 24, 2012, Turf iNfo for the North Central US
There are a couple things we are currently doing to combat the effects of the weather.
The first is venting the greens. Venting is the process of creating small holes in the putting green surface with the intention of improving gas exchange, improving water infiltration, and allowing the soil profile to dry down to the proper moisture levels. Essentially we are aerifying the greens only with smaller solid time so we do not disrupt play. We will try and repeat this process every 14-21 days through the summer.
The following pictures and video illustrate the venting process on the greens. We first punch a 3" to 4" deep hole and follow that with a roller to smooth the surface for play. We do the same process to the fairways with larger and longer tines and without the rolling.
The second thing we will do is dial back our overhead irrigation. To prevent our soils from becoming saturated, we will rely on shorter and more precise watering cycles and syringing. Our goal is to apply only enough water to allow the plant to maintain its metabolic processes and no more beyond that. Excess water leads to wet wilt, disease, and saturated soils.
Mother Nature will always have the upper hand but we are going to give ourselves every advantage that we can.
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