- Average high temperature of 92.8°F, with a maximum high temperature of 99°F on July 22nd
- Average low temperature of 72.7°F, with a maximum low temperature of 77°F on July 28th
- Total rainfall from Monday, July 18th to Monday, August 2nd was 4.36"
What these numbers illustrate is one of the hottest and wettest stretches central Ohio has seen in at least 16 years. While an the average for the period was only 8°F warmer than the historical average of 85°F, this was not a one or two day event but, a prolonged two week heat wave. Additionally, the warmest low temperature of 77°F on July 28th was the highest low temperature recorded in Columbus in 124 years. Moreover, the 4.36" of rainfall in just the last two weeks exceeded the entire July monthly average of 4.09". Simply put, hot and wet together spells trouble for turf and in this case both the heat and moisture were excessive.
All of the above statistics and elements play a part in the decline of turf but, perhaps the most important metric is the night time low temperatures. Any time the low temperature is above 68°F there is a concern that disease pressure is elevated and also that the opportunity for recovery is diminished. The turf plant has physiological processes "built-in" to recover from the stresses of hot days during the night when low temperatures are between 40°F and 68°F. As was mentioned previously, above 68°F some of those processes are not as efficient, and once low temperatures approach the low to mid 70's the efficiency of the recovery drops immensely. To use the analogy of a credit card: On a 90°F plus day the grass plant spends $10 to stay alive and at night as temperatures cool the plant pays back 100% of its debt when temperature are in the optimum range. However, as the night time low temperature approaches and exceeds 68°F, the payback on that $10 debt may only be 50%-75% or perhaps less. Now the turf plant is carrying a balance of debt and when it continues to do this day after day (such as what we have seen in the last two weeks), the amount of debt on the turf plant becomes unsustainable or unrecoverable and that is when we begin to see decline or in some cases death.
The bottom line is that as temperatures begin to moderate back to more seasonable levels, we'll see some improvement in the limited areas that are struggling right now. A few nights in a row with temperatures in the 50's would do wonders for the turf as it works to get through this latest round of extreme heat. From our perspective as a Turf Staff, our goals remain to provide the best playing conditions possible, which in the recent days means exercising some restraint and care knowing that some the club's biggest golf events are still upcoming.